diff --git a/html/extra-networks-pane.html b/html/extra-networks-pane.html
index a5fbed415..4c395a531 100644
--- a/html/extra-networks-pane.html
+++ b/html/extra-networks-pane.html
@@ -153,33 +153,41 @@
         </div>
     </div>
     <div class="extra-network-content--container">
-        <div class="extra-network-content extra-network-content--dirs-view styled-scrollbar">
-            {dirs_html}
-        </div>
-        <div class="extra-network-content--tree-and-cards-view resize-handle-row">
-            <div class="extra-network-content extra-network-content--tree-view resize-handle-col"
-                style="{tree_view_style}">
-                <div id='{tabname}_{extra_networks_tabname}_tree_list_loading_splash' class='extra-network-list-splash'>
-                    {tree_list_loading_splash_content}</div>
-                <div id='{tabname}_{extra_networks_tabname}_tree_list_no_data_splash'
-                    class='extra-network-list-splash hidden'>{tree_list_no_data_splash_content}</div>
-                <div id='{tabname}_{extra_networks_tabname}_tree_list_scroll_area'
-                    class='styled-scrollbar clusterize-scroll'>
-                    <div id='{tabname}_{extra_networks_tabname}_tree_list_content_area'
-                        class='extra-network-tree-content clusterize-content'></div>
+        <div class="extra-network-content--main-view resize-grid">
+            <div class="resize-grid--row" style="{dirs_view_row_style}" {dirs_view_row_data_attributes}>
+                <div class="resize-grid--col" style="flex: 1;">
+                    <div class="extra-network-content extra-network-content--dirs-view styled-scrollbar">
+                        {dirs_html}
+                    </div>
                 </div>
             </div>
-            <div class="extra-network-content extra-network-content--card-view extra-network-cards resize-handle-col"
-                style="{card_view_style}">
-                <div id='{tabname}_{extra_networks_tabname}_card_list_loading_splash' class='extra-network-list-splash'>
-                    {card_list_loading_splash_content}</div>
-                <div id='{tabname}_{extra_networks_tabname}_card_list_no_data_splash'
-                    class='extra-network-list-splash hidden'>{card_list_no_data_splash_content}
+            <div class="resize-grid--row" style="{tree_and_card_view_row_style}" {tree_and_card_view_row_data_attributes}>
+                <div class="resize-grid--col extra-network-content extra-network-content--tree-view"
+                    style="{tree_view_style}" {tree_view_data_attributes}>
+                    <div id='{tabname}_{extra_networks_tabname}_tree_list_loading_splash'
+                        class='extra-network-list-splash'>
+                        {tree_list_loading_splash_content}</div>
+                    <div id='{tabname}_{extra_networks_tabname}_tree_list_no_data_splash'
+                        class='extra-network-list-splash hidden'>{tree_list_no_data_splash_content}</div>
+                    <div id='{tabname}_{extra_networks_tabname}_tree_list_scroll_area'
+                        class='styled-scrollbar clusterize-scroll'>
+                        <div id='{tabname}_{extra_networks_tabname}_tree_list_content_area'
+                            class='extra-network-tree-content clusterize-content'></div>
+                    </div>
                 </div>
-                <div id='{tabname}_{extra_networks_tabname}_card_list_scroll_area'
-                    class='styled-scrollbar clusterize-scroll'>
-                    <div id='{tabname}_{extra_networks_tabname}_card_list_content_area'
-                        class='extra-network-card-content clusterize-content'></div>
+                <div class="resize-grid--col extra-network-content extra-network-content--card-view extra-network-cards"
+                    style="{card_view_style}" {card_view_data_attributes}>
+                    <div id='{tabname}_{extra_networks_tabname}_card_list_loading_splash'
+                        class='extra-network-list-splash'>
+                        {card_list_loading_splash_content}</div>
+                    <div id='{tabname}_{extra_networks_tabname}_card_list_no_data_splash'
+                        class='extra-network-list-splash hidden'>{card_list_no_data_splash_content}
+                    </div>
+                    <div id='{tabname}_{extra_networks_tabname}_card_list_scroll_area'
+                        class='styled-scrollbar clusterize-scroll'>
+                        <div id='{tabname}_{extra_networks_tabname}_card_list_content_area'
+                            class='extra-network-card-content clusterize-content'></div>
+                    </div>
                 </div>
             </div>
         </div>
diff --git a/javascript/extraNetworks.js b/javascript/extraNetworks.js
index 87082b847..968d8654c 100644
--- a/javascript/extraNetworks.js
+++ b/javascript/extraNetworks.js
@@ -15,6 +15,7 @@
     debounce,
     waitForBool,
     copyToClipboard,
+    resizeGridSetup,
 */
 /*eslint no-undef: "error"*/
 
@@ -115,6 +116,7 @@ class ExtraNetworksTab {
     tree_list_splash_state = null;
     directory_filters = {};
     list_button_states = {};
+    resize_grid = null;
     constructor({tabname, extra_networks_tabname}) {
         this.tabname = tabname;
         this.extra_networks_tabname = extra_networks_tabname;
@@ -195,6 +197,8 @@ class ExtraNetworksTab {
         this.card_view_en = false;
         this.directory_filters = {};
         this.list_button_states = {};
+        this.resize_grid.destroy();
+        this.resize_grid = null;
     }
 
     async registerPrompt() {
@@ -360,19 +364,9 @@ class ExtraNetworksTab {
         const div_dirs = this.container_elem.querySelector(".extra-network-content--dirs-view");
         const div_tree = this.container_elem.querySelector(".extra-network-content--tree-view");
         const div_card = this.container_elem.querySelector(".extra-network-content--card-view");
-        // Remove "hidden" class if button is enabled, otherwise add it.
-        div_dirs.classList.toggle("hidden", !this.dirs_view_en);
-        div_tree.classList.toggle("hidden", !this.tree_view_en);
-        div_card.classList.toggle("hidden", !this.card_view_en);
-
-        // Apply the current resize handle classes.
-        const resize_handle_row = div_tree.closest(".resize-handle-row");
-        resize_handle_row.classList.toggle("resize-handle-hidden", !this.tree_view_en || !this.card_view_en);
-        if (this.tree_view_en && !this.card_view_en) {
-            div_tree.style.flexGrow = 1;
-        } else {
-            div_tree.style.flexGrow = null;
-        }
+        this.resize_grid.toggleElem(div_dirs, this.dirs_view_en);
+        this.resize_grid.toggleElem(div_tree, this.tree_view_en);
+        this.resize_grid.toggleElem(div_card, this.card_view_en);
 
         await Promise.all([this.setupTreeList(), this.setupCardList()]);
         this.tree_list.enable(this.tree_view_en);
@@ -404,21 +398,17 @@ class ExtraNetworksTab {
         });
         this.showControls();
 
+        if (isNullOrUndefined(this.resize_grid)) {
+            const elem = this.container_elem.querySelector(".resize-grid");
+            this.resize_grid = resizeGridSetup(elem, {id: `${this.tabname_full}_resize_grid`});
+        }
+
         const div_dirs = this.container_elem.querySelector(".extra-network-content--dirs-view");
         const div_tree = this.container_elem.querySelector(".extra-network-content--tree-view");
         const div_card = this.container_elem.querySelector(".extra-network-content--card-view");
-        div_dirs.classList.toggle("hidden", !this.dirs_view_en);
-        div_tree.classList.toggle("hidden", !this.tree_view_en);
-        div_card.classList.toggle("hidden", !this.card_view_en);
-
-        // Apply the current resize handle classes.
-        const resize_handle_row = div_tree.closest(".resize-handle-row");
-        resize_handle_row.classList.toggle("resize-handle-hidden", !this.tree_view_en || !this.card_view_en);
-        if (this.tree_view_en && !this.card_view_en) {
-            div_tree.style.flexGrow = 1;
-        } else {
-            div_tree.style.flexGrow = null;
-        }
+        this.resize_grid.toggleElem(div_dirs, this.dirs_view_en);
+        this.resize_grid.toggleElem(div_tree, this.tree_view_en);
+        this.resize_grid.toggleElem(div_card, this.card_view_en);
 
         this.tree_list.enable(this.tree_view_en);
         this.card_list.enable(this.card_view_en);
@@ -1195,22 +1185,9 @@ async function extraNetworksControlTreeViewOnClick(event) {
     tab.tree_view_en = "selected" in btn.dataset;
 
     const div_tree = tab.container_elem.querySelector(".extra-network-content--tree-view");
-    div_tree.classList.toggle("hidden", !tab.tree_view_en);
+    tab.resize_grid.toggleElem(div_tree, tab.tree_view_en);
     tab.tree_list.enable(tab.tree_view_en);
 
-    // Apply the resize-handle-hidden class to the resize-handle-row.
-    // NOTE: This can be simplified using only css with the ":has" selector however
-    // this is only recently supported in firefox. So for now we just add a class
-    // to the resize-handle-row instead.
-    const resize_handle_row = div_tree.closest(".resize-handle-row");
-    resize_handle_row.classList.toggle("resize-handle-hidden", !tab.card_view_en || !tab.tree_view_en);
-
-    if (tab.tree_view_en && !tab.card_view_en) {
-        div_tree.style.flexGrow = 1;
-    } else {
-        div_tree.style.flexGrow = null;
-    }
-
     // If the tree list hasn't loaded yet, we need to force it to load.
     // This can happen if tree view is disabled by default or before refresh.
     // Then after refresh, enabling the tree view will require a load.
@@ -1232,9 +1209,8 @@ function extraNetworksControlDirsViewOnClick(event) {
     btn.toggleAttribute("data-selected");
     tab.dirs_view_en = "selected" in btn.dataset;
 
-    tab.container_elem.querySelector(
-        ".extra-network-content--dirs-view"
-    ).classList.toggle("hidden", !tab.dirs_view_en);
+    const div_dirs = tab.container_elem.querySelector(".extra-network-content--dirs-view");
+    tab.resize_grid.toggleElem(div_dirs, tab.dirs_view_en);
 
     tab.applyListButtonStates();
 }
@@ -1250,24 +1226,10 @@ async function extraNetworksControlCardViewOnClick(event) {
     btn.toggleAttribute("data-selected");
     tab.card_view_en = "selected" in btn.dataset;
 
-    const div_tree = tab.container_elem.querySelector(".extra-network-content--tree-view");
     const div_card = tab.container_elem.querySelector(".extra-network-content--card-view");
-    div_card.classList.toggle("hidden", !tab.card_view_en);
+    tab.resize_grid.toggleElem(div_card, tab.card_view_en);
     tab.card_list.enable(tab.card_view_en);
 
-    // Apply the resize-handle-hidden class to the resize-handle-row.
-    // NOTE: This can be simplified using only css with the ":has" selector however
-    // this is only recently supported in firefox. So for now we just add a class
-    // to the resize-handle-row instead.
-    const resize_handle_row = div_card.closest(".resize-handle-row");
-    resize_handle_row.classList.toggle("resize-handle-hidden", !tab.card_view_en || !tab.tree_view_en);
-
-    if (tab.tree_view_en && !tab.card_view_en) {
-        div_tree.style.flexGrow = 1;
-    } else {
-        div_tree.style.flexGrow = null;
-    }
-
     // If the tree list hasn't loaded yet, we need to force it to load.
     // This can happen if tree view is disabled by default or before refresh.
     // Then after refresh, enabling the tree view will require a load.
diff --git a/javascript/resizeGrid.js b/javascript/resizeGrid.js
new file mode 100644
index 000000000..837484f6e
--- /dev/null
+++ b/javascript/resizeGrid.js
@@ -0,0 +1,1165 @@
+// Prevent eslint errors on functions defined in other files.
+/*global
+    isNullOrUndefinedThrowError,
+    isNullOrUndefinedLogError,
+    isNullOrUndefined,
+    isString,
+    cssRelativeUnitToPx,
+    isNumber,
+    isElementThrowError,
+    isElement,
+*/
+/*eslint no-undef: "error"*/
+
+// Should be between 0 and 15. Any higher and the delay becomes noticable.
+// Higher values reduce computational load.
+const MOVE_TIME_DELAY_MS = 15;
+// Prevents handling element resize events too quickly. Lower values increase
+// computational load and may lead to lag when resizing.
+const RESIZE_DEBOUNCE_TIME_MS = 100;
+// The timeframe in which a second pointerup event must be fired to be treated
+// as a double click.
+const DBLCLICK_TIME_MS = 500;
+// The padding around the draggable resize handle.
+// NOTE: Must be an even number.
+const PAD_PX = 16;
+if (!(PAD_PX > 0 && PAD_PX % 2 === 0)) {
+    throw new Error('PAD_PX must be an even number > 0');
+}
+
+const resize_grids = {};
+
+/* ==== HELPER FUNCTIONS ==== */
+const _gen_id_string = () => {
+    return Math.random().toString(16).slice(2);
+};
+
+const _get_unique_id = () => {
+    let id = _gen_id_string();
+    while (id in Object.keys(resize_grids)) {
+        id = _gen_id_string();
+    }
+    return id;
+};
+
+const _parse_array_type = (arr, type_check_fn) => {
+    /** Validates that a variable is an array with members of a specified type.
+     * `type_check_fn` must accept array elements as arguments and return whether
+     * they match the expected type.
+     */
+    isNullOrUndefinedThrowError(type_check_fn);
+    if (isNullOrUndefined(arr)) {
+        return [];
+    }
+    if (!Array.isArray(arr) && type_check_fn(arr)) {
+        return [arr];
+    } else if (Array.isArray(arr) && arr.every((x) => type_check_fn(x))) {
+        return arr;
+    } else {
+        throw new Error('Invalid array types:', arr);
+    }
+};
+
+const _axis_to_int = (axis) => {
+    /** Converts an axis to a standardized axis integer.
+     *  Returns:
+     *      "x" or 0: 0
+     *      "y" or 1: 1
+     */
+    if (axis === 0 || axis === 'x') {
+        return 0;
+    } else if (axis === 1 || axis === 'y') {
+        return 1;
+    } else {
+        throw new Error(`"Axis" expected (x (0), y (1)), got: ${axis}`);
+    }
+};
+
+class ResizeGridHandle {
+    /** Class defining the clickable "handle" between two grid items. */
+    visible = true;
+    id = null; // unique identifier for this instance.
+    pad_px = PAD_PX;
+    constructor({id, parent, axis, class_list} = {}) {
+        this.id = isNullOrUndefined(id) ? _gen_id_string() : id;
+        this.parent = parent;
+        this.elem = document.createElement('div');
+        this.elem.id = id;
+        this.elem.classList.add('resize-grid--handle');
+        _parse_array_type(class_list, isString).forEach((class_name) => {
+            this.elem.classList.add(class_name);
+        });
+
+        this.axis = _axis_to_int(axis);
+
+        if (this.axis === 0) {
+            this.elem.style.minHeight = this.pad_px + 'px';
+            this.elem.style.maxHeight = this.pad_px + 'px';
+        } else if (this.axis === 1) {
+            this.elem.style.minWidth = this.pad_px + 'px';
+            this.elem.style.maxWidth = this.pad_px + 'px';
+        }
+    }
+
+    destroy() {
+        this.elem.remove();
+    }
+
+    show() {
+        this.elem.classList.remove('hidden');
+        this.visible = true;
+    }
+
+    hide() {
+        this.elem.classList.add('hidden');
+        this.visible = false;
+    }
+}
+
+class ResizeGridItem {
+    /** Class defining the cells in a grid. These can be rows or columns. */
+    handle = null;
+    visible = true;
+    pad_px = PAD_PX;
+    constructor({id, parent, elem, axis} = {}) {
+        this.id = isNullOrUndefined(id) ? _gen_id_string() : id;
+        this.parent = parent; // the parent class instance
+        this.elem = elem;
+        this.axis = _axis_to_int(axis);
+
+        this.is_flex_grow = Boolean(parseInt(this.elem.style.flexGrow));
+        this.default_is_flex_grow = this.is_flex_grow;
+        let flex_basis = parseInt(cssRelativeUnitToPx(this.elem.style.flexBasis));
+        // If user specifies data-min-size, then the flexBasis is just used to set
+        // the initial size.
+        if ('minSize' in this.elem.dataset) {
+            this.min_size = parseInt(cssRelativeUnitToPx(this.elem.dataset.minSize));
+            if (isNumber(flex_basis)) {
+                this.base_size = flex_basis;
+            } else {
+                this.base_size = this.min_size;
+            }
+        } else if (isNumber(flex_basis)) {
+            this.min_size = flex_basis;
+            this.base_size = flex_basis;
+        } else {
+            this.min_size = 0;
+            this.base_size = 0;
+        }
+
+        const dims = this.elem.getBoundingClientRect();
+        this.base_size =
+            this.axis === 0 ? parseInt(dims.height) : parseInt(dims.width);
+        this.elem.dataset.id = this.id;
+        this.original_css_text = this.elem.style.cssText;
+    }
+
+    render({force_flex_grow, reset} = {}) {
+        /** Sets the element's flex styles. */
+        force_flex_grow = force_flex_grow === true;
+        reset = reset === true;
+
+        this.elem.style.flexShrink = 0;
+        if (reset) {
+            this.elem.style.flexGrow = Number(this.is_flex_grow);
+            this.elem.style.flexBasis = parseInt(this.base_size) + 'px';
+        } else if (force_flex_grow) {
+            this.elem.style.flexGrow = 1;
+        } else {
+            this.elem.style.flexGrow = Number(this.is_flex_grow);
+            if (!this.is_flex_grow) {
+                this.elem.style.flexBasis =
+                    parseInt(Math.max(this.min_size, this.getSize())) + 'px';
+            }
+        }
+    }
+
+    destroy() {
+        if (!isNullOrUndefined(this.handle)) {
+            this.handle.destroy();
+            this.handle = null;
+        }
+        // Revert changes to the container element.
+        this.elem.style.cssText = this.original_css_text;
+        if (!this.elem.style.cssText) {
+            this.elem.removeAttribute('style');
+        }
+    }
+
+    shrink(px, {limit_to_base} = {}) {
+        /** Shrink size along axis by specified pixels. Returns remainder. */
+        limit_to_base = limit_to_base === true;
+        const target_size = limit_to_base ? this.base_size : this.min_size;
+        const curr_size = this.getSize();
+
+        if (px === -1) {
+            // shrink to min_size
+            this.setSize(target_size);
+            return 0;
+        } else if (curr_size - target_size < px) {
+            this.setSize(target_size);
+            return px - (curr_size - target_size);
+        } else {
+            this.setSize(curr_size - px);
+            return 0;
+        }
+    }
+
+    grow(px, {only_if_flex} = {}) {
+        /** Grows along axis and returns the amount grown in pixels. */
+        only_if_flex = only_if_flex === true;
+        if (only_if_flex && !this.is_flex_grow) {
+            return 0;
+        }
+        let new_size;
+        const curr_size = this.getSize();
+        if (px === -1) {
+            // grow to fill container (only works if visible)
+            // set flexGrow to 1 to expand to max width so we can calc new width.
+            this.elem.style.flexGrow = 1;
+            new_size = this.getSize();
+            this.elem.style.flexGrow = Number(this.is_flex_grow);
+        } else {
+            new_size = curr_size + px;
+        }
+        this.setSize(new_size);
+        return new_size - curr_size;
+    }
+
+    setSize(px) {
+        this.elem.style.flexBasis = parseInt(px) + 'px';
+        this.render();
+    }
+
+    getSize() {
+        // If this item is visible, then we can use the computed dimensions.
+        // Otherwise we are forced to use the flexBasis inline style.
+        if (this.visible) {
+            const dims = this.elem.getBoundingClientRect();
+            return this.axis === 0 ? parseInt(dims.height) : parseInt(dims.width);
+        } else {
+            return parseInt(this.elem.style.flexBasis);
+        }
+    }
+
+    genHandle(class_list) {
+        /** Generates a ResizeGridHandle after this item based on the axis. */
+        this.handle = new ResizeGridHandle({
+            id: `${this.id}_handle`,
+            parent: this.parent,
+            axis: this.axis,
+            class_list: class_list,
+        });
+        if (isElement(this.elem.nextElementSibling)) {
+            this.elem.parentElement.insertBefore(
+                this.handle.elem,
+                this.elem.nextSibling
+            );
+        } else {
+            this.elem.parentElement.appendChild(this.handle.elem);
+        }
+    }
+
+    show() {
+        /** Shows this item and its ResizeGridHandle. */
+        this.elem.classList.remove('hidden');
+        // Only show the handle if there is another ResizeGridItem after this one.
+        if (!isNullOrUndefined(this.handle.elem.nextSibling)) {
+            this.handle.show();
+        }
+        this.visible = true;
+    }
+
+    hide() {
+        /** Hides this item and its ResizeGridHandle. */
+        this.elem.classList.add('hidden');
+        this.handle.hide();
+        this.visible = false;
+    }
+}
+
+class ResizeGridContainer {
+    /** Class defining a collection of ResizeGridItem and ResizeGridHandle instances. */
+    constructor({id, parent, elem} = {}) {
+        this.id = isNullOrUndefined(id) ? _gen_id_string() : id;
+        this.parent = parent;
+        this.elem = elem;
+        this.original_css_text = this.elem.style.cssText;
+
+        this.grid = [];
+        this.rows = [];
+        this.id_map = {};
+        this.added_outer_row = false;
+    }
+
+    destroy() {
+        this.rows.forEach((row) => {
+            row.destroy();
+        });
+        this.rows = null;
+        if (this.added_outer_row) {
+            this.elem.innerHTML = this.elem.querySelector(
+                ':scope > .resize-grid--row'
+            ).innerHTML;
+        }
+        super.destroy();
+    }
+
+    addRow(id, elem, row_idx) {
+        /** Generates a ResizeGridItem and ResizeGridHandle for a row element. */
+        const row = new ResizeGridItem({
+            id: id,
+            parent: this,
+            elem: elem,
+            axis: 0,
+        });
+        row.genHandle('resize-grid--row-handle');
+        row.elem.dataset.row = row_idx;
+        this.rows.push(row);
+        this.id_map[id] = row;
+        return row;
+    }
+
+    addCol(id, elem, row_idx, col_idx) {
+        /** Generates a ResizeGridItem and ResizeGridHandle for a column element. */
+        const col = new ResizeGridItem({
+            id: id,
+            parent: this,
+            elem: elem,
+            axis: 1,
+        });
+        col.genHandle('resize-grid--col-handle');
+        col.elem.dataset.row = row_idx;
+        col.elem.dataset.col = col_idx;
+        this.grid[row_idx].push(col);
+        this.id_map[id] = col;
+        return col;
+    }
+
+    build() {
+        /** Generates rows/cols based on this instance element's content. */
+        let row_elems = Array.from(this.elem.querySelectorAll('.resize-grid--row'));
+        // If we do not have any rows, then we generate a single row to contain the cols.
+        if (!row_elems.length) {
+            const elem = document.createElement('div');
+            elem.classList.add('resize-grid--row');
+            elem.append(...this.elem.children);
+            this.elem.replaceChildren(elem);
+            row_elems = [elem];
+            // track this addition so we can remove it later.
+            this.added_outer_row = true;
+        }
+
+        // Make sure that if we only have one row, that it fills the container.
+        if (row_elems.length === 1 && !row_elems[0].style.flexBasis) {
+            row_elems[0].style.flexGrow = 1;
+            row_elems[0].style.flexBasis =
+                parseInt(this.elem.getBoundingClientRect().height) + 'px';
+        }
+
+        let id = 0;
+        this.grid = [...Array(row_elems.length)].map((_) => []);
+        row_elems.forEach((row_elem, i) => {
+            this.addRow(id++, row_elem, i);
+            const col_elems = row_elem.querySelectorAll('.resize-grid--col');
+            col_elems.forEach((col_elem, j) => {
+                this.addCol(id++, col_elem, i, j);
+            });
+            this.grid[i][this.grid[i].length - 1].handle.hide();
+        });
+        this.rows[this.rows.length - 1].handle.hide();
+
+        // Now that all handles are added, we need to render the flex styles for each item.
+        for (let i = 0; i < this.rows.length; i++) {
+            this.rows[i].render({reset: true});
+            for (let j = 0; j < this.grid[i].length; j++) {
+                this.grid[i][j].render({reset: true});
+            }
+        }
+    }
+
+    getByElem(elem) {
+        return this.id_map[elem.dataset.id];
+    }
+
+    getByIdx({row_idx, col_idx} = {}) {
+        /** Returns the ResizeGridItem at the row/col index. */
+        row_idx = parseInt(row_idx);
+        col_idx = parseInt(col_idx);
+        if (
+            (!isNumber(row_idx) && !isNumber(col_idx)) ||
+            (!isNumber(row_idx) && isNumber(col_idx))
+        ) {
+            console.error('Invalid row/col idx:', row_idx, col_idx);
+            return;
+        }
+        if (isNumber(row_idx) && !isNumber(col_idx)) {
+            if (row_idx >= this.rows.length) {
+                console.error(
+                    `row_idx out of range: (${row_idx} > ${this.rows.length})`
+                );
+                return;
+            }
+            return this.rows[row_idx];
+        }
+        if (isNumber(row_idx) && isNumber(col_idx)) {
+            if (row_idx >= this.grid.length) {
+                console.error(
+                    `row_idx out of range: (${row_idx} > ${this.grid.length})`
+                );
+                return;
+            }
+            if (col_idx >= this.grid[row_idx].length) {
+                console.error(
+                    `col_idx out of range: (${col_idx} > ${this.grid[row_idx].length})`
+                );
+                return;
+            }
+            return this.grid[row_idx][col_idx];
+        }
+    }
+
+    updateVisibleHandles() {
+        /** Sets the visibility of each ResizeGridHandle based on surrounding items. */
+        const last_vis_rows_idx = this.rows.findLastIndex((x) => x.visible);
+        for (let i = 0; i < this.rows.length; i++) {
+            const last_vis_grid_idx = this.grid[i].findLastIndex((x) => x.visible);
+            for (let j = 0; j < this.grid[i].length; j++) {
+                const item = this.getByIdx({row_idx: i, col_idx: j});
+                if (isNullOrUndefined(item)) {
+                    continue;
+                }
+
+                // Don't show handle if item is last column in row.
+                if (this.grid[i][j].visible && j !== last_vis_grid_idx) {
+                    this.grid[i][j].handle.show();
+                } else {
+                    this.grid[i][j].handle.hide();
+                }
+            }
+
+            const item = this.getByIdx({row_idx: i});
+            if (isNullOrUndefined(item)) {
+                continue;
+            }
+
+            // Don't show handle if item is last row in grid.
+            if (this.rows[i].visible && i !== last_vis_rows_idx) {
+                this.rows[i].handle.show();
+            } else {
+                this.rows[i].handle.hide();
+            }
+        }
+    }
+
+    makeRoomForItem(item, siblings, item_idx, {use_base_size} = {}) {
+        /** Shrinks items along axis until the supplied item can fit. */
+        use_base_size = use_base_size === true;
+        let tot = use_base_size ? item.base_size : item.getSize();
+        // Get the item after this item's handle.
+        let sibling = siblings.slice(item_idx + 1).find((x) => x.visible);
+        if (isNullOrUndefined(sibling)) {
+            // No items after this item. Instead get the item just before this item.
+            sibling = siblings.slice(0, item_idx).findLast((x) => x.visible);
+            isNullOrUndefinedThrowError(sibling); // Indicates programmer error.
+            // Last item so we want to hide its handle.
+            item.handle.hide();
+            // Add previous item handle's size
+            tot += sibling.handle.pad_px;
+        } else {
+            // Need to add handle between this item and next item.
+            item.handle.show();
+            tot += item.handle.pad_px;
+        }
+
+        const sibling_idx = siblings.indexOf(sibling);
+
+        let rem = tot;
+        rem = sibling.shrink(rem, {limit_to_base: use_base_size});
+        if (rem <= 0) {
+            return;
+        }
+        // Shrink from flexGrow items next starting from the end.
+        if (rem > 0) {
+            const others = siblings.filter(
+                (x) =>
+                    x.visible && x.is_flex_grow && siblings.indexOf(x) !== sibling_idx
+            );
+            for (const other of others.slice().reverse()) {
+                rem = other.shrink(rem, {limit_to_base: use_base_size});
+                if (rem <= 0) {
+                    return;
+                }
+            }
+        }
+        // Now shrink from non-flexGrow items starting from the end.
+        if (rem > 0) {
+            const others = siblings.filter(
+                (x) =>
+                    x.visible && !x.is_flex_grow && siblings.indexOf(x) !== sibling_idx
+            );
+            for (const other of others.slice().reverse()) {
+                rem = other.shrink(rem, {limit_to_base: use_base_size});
+                if (rem <= 0) {
+                    return;
+                }
+            }
+        }
+
+        // Shrink the item itself if we still don't have room.
+        if (rem > 0) {
+            rem = item.shrink(rem, {limit_to_base: use_base_size});
+            if (rem <= 0) {
+                return;
+            }
+        }
+
+        // If still not enough room, try again but use the base sizes.
+        if (rem > 0 && !use_base_size) {
+            this.makeRoomForItem(item, siblings, item_idx, {use_base_size: true});
+            return;
+        }
+        // If we still couldn't make room, this indicates programmer error.
+        throw new Error(`No space for row. tot: ${tot}, rem: ${rem}`);
+    }
+
+    growToFill(item, siblings, item_idx, tot_px, max_px) {
+        /** Expands item along axis until the axis has no remaining space. */
+        // Expand the item that was attached via the hidden item's handle first.
+        let sibling = siblings.slice(item_idx + 1).find((x) => x.visible);
+        if (isNullOrUndefined(sibling)) {
+            // Otherwise, expand the previous attached item.
+            sibling = siblings.slice(0, item_idx).findLast((x) => x.visible);
+            isNullOrUndefinedThrowError(sibling); // Indicates programmer error.
+        } else {
+            tot_px += item.pad_px;
+        }
+        // Hide sibling's handle if sibling is last visible item.
+        if (
+            siblings
+                .slice(siblings.findIndex((x) => x === sibling) + 1)
+                .every((x) => !x.visible)
+        ) {
+            if (sibling.handle.visible) {
+                sibling.handle.hide();
+                tot_px += sibling.pad_px;
+            }
+        }
+
+        // If we are growing sibling to fill, then just set flexGrow=1.
+        if (
+            siblings.length <= 2 ||
+            siblings.every((x) => !x.visible && x !== sibling && x !== item)
+        ) {
+            sibling.render({force_flex_grow: true});
+        } else {
+            const sibling_size = sibling.getSize();
+            if (tot_px + sibling_size > max_px) {
+                tot_px = max_px - sibling_size;
+            }
+            sibling.grow(tot_px);
+        }
+    }
+
+    showRow(row_idx, {show_empty_row} = {}) {
+        /** Makes space for the row then shows it. */
+        show_empty_row = show_empty_row === true;
+        row_idx = parseInt(row_idx);
+        const item = this.getByIdx({row_idx: row_idx});
+        isNullOrUndefinedThrowError(item);
+
+        if (item.visible) {
+            return;
+        }
+
+        if (item.axis !== 0) {
+            console.error('Expected row, got col:', item);
+            return;
+        }
+
+        // If no columns are visible, then we can't show the row.
+        if (this.grid[row_idx].every((x) => !x.visible) && !show_empty_row) {
+            console.error('No visible columns in row. Cannot show.');
+            return;
+        }
+
+        // All rows are hidden. We just show this row and make it fill the container.
+        if (this.rows.every((x) => !x.visible)) {
+            item.show();
+            item.handle.hide();
+            item.render({force_flex_grow: true});
+        } else {
+            this.makeRoomForItem(item, this.rows, row_idx);
+            item.show();
+            if (this.rows.slice(row_idx + 1).every((x) => !x.visible)) {
+                // If this is the last visible row, hide the handle.
+                item.handle.hide();
+            }
+            const prev_item = this.rows.slice(0, row_idx).find((x) => x.visible);
+            if (!isNullOrUndefined(prev_item)) {
+                prev_item.handle.show();
+            }
+            item.render();
+        }
+    }
+
+    showCol(row_idx, col_idx) {
+        /** Makes space for the column then shows it. */
+        row_idx = parseInt(row_idx);
+        col_idx = parseInt(col_idx);
+        const item = this.getByIdx({row_idx: row_idx, col_idx: col_idx});
+        isNullOrUndefinedThrowError(item);
+
+        if (item.visible) {
+            return;
+        }
+
+        if (item.axis !== 1) {
+            console.error('Expected col, got row:', item);
+            return;
+        }
+
+        // If the row isn't visible, we need to show it before we can show columns.
+        if (!this.rows[row_idx].visible) {
+            this.showRow(row_idx, {show_empty_row: true});
+        }
+
+        // All cols are hidden. We just show this col and make it fill the row.
+        if (this.grid[row_idx].every((x) => !x.visible)) {
+            item.show();
+            item.handle.hide();
+            item.render({force_flex_grow: true});
+        } else {
+            this.makeRoomForItem(item, this.grid[row_idx], col_idx);
+            item.show();
+            if (this.grid[row_idx].slice(col_idx + 1).every((x) => !x.visible)) {
+                // If this is the last visible col, hide the handle.
+                item.handle.hide();
+            }
+            const prev_item = this.grid[row_idx]
+                .slice(0, col_idx)
+                .find((x) => x.visible);
+            if (!isNullOrUndefined(prev_item)) {
+                prev_item.handle.show();
+            }
+            item.render();
+        }
+    }
+
+    hideRow(row_idx) {
+        /** Hides a row and resizes other rows to fill the gap. */
+        row_idx = parseInt(row_idx);
+        const item = this.getByIdx({row_idx: row_idx});
+        isNullOrUndefinedThrowError(item);
+
+        if (!item.visible) {
+            return;
+        }
+
+        if (item.axis !== 0) {
+            console.error('Expected row, got col:', item);
+            return;
+        }
+
+        const max_height = this.elem.getBoundingClientRect().height;
+        let tot_px = item.elem.getBoundingClientRect().height;
+        item.hide();
+        // If no other rows are visible, we don't need to do anything else.
+        if (this.rows.every((x) => !x.visible)) {
+            return;
+        }
+
+        this.growToFill(item, this.rows, row_idx, tot_px, max_height);
+    }
+
+    hideCol(row_idx, col_idx) {
+        /** Hides a column and resizes other columns to fill the gap. */
+        row_idx = parseInt(row_idx);
+        col_idx = parseInt(col_idx);
+        const item = this.getByIdx({row_idx: row_idx, col_idx: col_idx});
+        isNullOrUndefinedThrowError(item);
+
+        if (!item.visible) {
+            return;
+        }
+
+        if (item.axis !== 1) {
+            console.error('Expected col, got row:', item);
+            return;
+        }
+
+        const max_width = this.elem.getBoundingClientRect().width;
+        let tot_px = item.elem.getBoundingClientRect().width;
+        item.hide();
+        // If no other cols are visible, hide the containing row.
+        if (this.grid[row_idx].every((x) => !x.visible)) {
+            this.hideRow(row_idx);
+            return;
+        }
+
+        this.growToFill(item, this.grid[row_idx], col_idx, tot_px, max_width);
+    }
+
+    show({row_idx, col_idx} = {}) {
+        /** Shows a row or column based on the provided row/col indices. */
+        row_idx = parseInt(row_idx);
+        col_idx = parseInt(col_idx);
+        if (isNumber(row_idx) && !isNumber(col_idx)) {
+            this.showRow(row_idx);
+        } else if (isNumber(row_idx) && isNumber(col_idx)) {
+            this.showCol(row_idx, col_idx);
+        } else {
+            throw new Error('Invalid parameters for row/col idx:', row_idx, col_idx);
+        }
+    }
+
+    hide({row_idx, col_idx} = {}) {
+        /** Hides a row or column based on the provided row/col indices. */
+        row_idx = parseInt(row_idx);
+        col_idx = parseInt(col_idx);
+        if (isNumber(row_idx) && !isNumber(col_idx)) {
+            this.hideRow(row_idx);
+        } else if (isNumber(row_idx) && isNumber(col_idx)) {
+            this.hideCol(row_idx, col_idx);
+        } else {
+            throw new Error('Invalid parameters for row/col idx:', row_idx, col_idx);
+        }
+    }
+
+    toggle({row_idx, col_idx, override} = {}) {
+        /** Toggles a row or column's visibility based on the provided row/col indices. */
+        row_idx = parseInt(row_idx);
+        col_idx = parseInt(col_idx);
+        const item = this.getByIdx({row_idx: row_idx, col_idx: col_idx});
+        isNullOrUndefinedThrowError(item);
+
+        let new_state = !item.visible;
+        if (override === true || override === false) {
+            new_state = override;
+        }
+
+        if (item.axis === 0) {
+            new_state ? this.showRow(row_idx) : this.hideRow(row_idx);
+        } else {
+            new_state ?
+                this.showCol(row_idx, col_idx) :
+                this.hideCol(row_idx, col_idx);
+        }
+    }
+}
+
+class ResizeGrid {
+    /** Class representing a resizable grid. */
+    event_abort_controller = null;
+    added_outer_row = false;
+    container = null;
+    setup_has_run = false;
+    prev_dims = null;
+    resize_observer = null;
+    resize_observer_timer;
+    constructor(id, elem) {
+        this.id = id;
+        this.elem = elem;
+        this.elem.dataset.gridId = this.id;
+    }
+
+    destroy() {
+        this.destroyEvents();
+        if (!isNullOrUndefined(this.container)) {
+            this.container.destroy();
+            this.container = null;
+        }
+        this.setup_has_run = false;
+    }
+
+    setup() {
+        /** Fully prepares this instance for use. */
+        if (!this.elem.querySelector('.resize-grid--row,.resize-grid--col')) {
+            throw new Error('Container has no rows or cols.');
+        }
+
+        if (!isNullOrUndefined(this.container)) {
+            this.container.destroy();
+            this.container = null;
+        }
+
+        this.container = new ResizeGridContainer(this, null, this.elem);
+        this.container.build();
+        this.prev_dims = this.elem.getBoundingClientRect();
+        this.setupEvents();
+        this.setup_has_run = true;
+    }
+
+    setupEvents() {
+        /** Sets up all event delegators and observers for this instance. */
+        this.event_abort_controller = new AbortController();
+        let prev;
+        let handle;
+        let next;
+        let touch_count = 0;
+        let dblclick_timer;
+        let last_move_time;
+
+        window.addEventListener(
+            'pointerdown',
+            (event) => {
+                if (event.target.hasPointerCapture(event.pointerId)) {
+                    event.target.releasePointerCapture(event.pointerId);
+                }
+                if (event.pointerType === 'mouse' && event.button !== 0) {
+                    return;
+                }
+                if (event.pointerType === 'touch') {
+                    touch_count++;
+                    if (touch_count !== 1) {
+                        return;
+                    }
+                }
+
+                const elem = event.target.closest('.resize-grid--handle');
+                if (!elem) {
+                    return;
+                }
+                // Clicked handles will always be between two elements. If the user
+                // somehow clicks an invisible handle then we have bigger problems.
+                prev = this.container.getByElem(elem.previousElementSibling);
+                if (!prev.visible) {
+                    const row_idx = prev.elem.dataset.row;
+                    const col_idx = prev.elem.dataset.col;
+                    const siblings =
+                        prev.axis === 0 ?
+                            this.container.rows :
+                            this.container.grid[row_idx];
+                    const idx = prev.axis === 0 ? row_idx : col_idx;
+                    prev = siblings.slice(0, idx).findLast((x) => x.visible);
+                }
+                handle = prev.handle;
+                next = this.container.getByElem(elem.nextElementSibling);
+                if (!next.visible) {
+                    const row_idx = next.elem.dataset.row;
+                    const col_idx = next.elem.dataset.col;
+                    const siblings =
+                        next.axis === 0 ?
+                            this.container.rows :
+                            this.container.grid[row_idx];
+                    const idx = next.axis === 0 ? row_idx : col_idx;
+                    next = siblings.slice(idx).find((x) => x.visible);
+                }
+
+                if (
+                    isNullOrUndefinedLogError(prev) ||
+                    isNullOrUndefinedLogError(handle) ||
+                    isNullOrUndefinedLogError(next)
+                ) {
+                    prev = null;
+                    handle = null;
+                    next = null;
+                    return;
+                }
+
+                event.preventDefault();
+                event.stopPropagation();
+
+                handle.elem.setPointerCapture(event.pointerId);
+
+                document.body.classList.add('resizing');
+                if (handle.axis === 0) {
+                    document.body.classList.add('resizing-col');
+                } else {
+                    document.body.classList.add('resizing-row');
+                }
+            },
+            {signal: this.event_abort_controller.signal}
+        );
+
+        window.addEventListener(
+            'pointermove',
+            (event) => {
+                if (
+                    isNullOrUndefined(prev) ||
+                    isNullOrUndefined(handle) ||
+                    isNullOrUndefined(next)
+                ) {
+                    return;
+                }
+
+                event.preventDefault();
+                event.stopPropagation();
+
+                const now = new Date().getTime();
+                if (!last_move_time || now - last_move_time > MOVE_TIME_DELAY_MS) {
+                    this.onMove(event, prev, handle, next);
+                    last_move_time = now;
+                }
+            },
+            {signal: this.event_abort_controller.signal}
+        );
+
+        window.addEventListener(
+            'pointerup',
+            (event) => {
+                if (
+                    isNullOrUndefined(prev) ||
+                    isNullOrUndefined(handle) ||
+                    isNullOrUndefined(next)
+                ) {
+                    return;
+                }
+
+                if (event.target.hasPointerCapture(event.pointerId)) {
+                    event.target.releasePointerCapture(event.pointerId);
+                }
+
+                if (event.pointerType === 'mouse' && event.button !== 0) {
+                    return;
+                }
+                if (event.pointerType === 'touch') {
+                    touch_count--;
+                }
+
+                event.preventDefault();
+                event.stopPropagation();
+
+                handle.elem.releasePointerCapture(event.pointerId);
+
+                document.body.classList.remove('resizing');
+                document.body.classList.remove('resizing-col');
+                document.body.classList.remove('resizing-row');
+
+                if (!dblclick_timer) {
+                    handle.elem.dataset.awaitDblClick = '';
+                    dblclick_timer = setTimeout(
+                        (elem) => {
+                            dblclick_timer = null;
+                            delete elem.dataset.awaitDblClick;
+                        },
+                        DBLCLICK_TIME_MS,
+                        handle.elem
+                    );
+                } else if ('awaitDblClick' in handle.elem.dataset) {
+                    clearTimeout(dblclick_timer);
+                    dblclick_timer = null;
+                    delete handle.elem.dataset.awaitDblClick;
+                    handle.elem.dispatchEvent(
+                        new CustomEvent('resize_handle_dblclick', {
+                            bubbles: true,
+                            detail: this,
+                        })
+                    );
+                }
+                prev = null;
+                handle = null;
+                next = null;
+            },
+            {signal: this.event_abort_controller.signal}
+        );
+
+        window.addEventListener(
+            'pointerout',
+            (event) => {
+                if (event.pointerType === 'touch') {
+                    touch_count--;
+                }
+            },
+            {signal: this.event_abort_controller.signal}
+        );
+
+        this.resize_observer = new ResizeObserver((entries) => {
+            for (const entry of entries) {
+                if (entry.target.id === this.elem.id) {
+                    clearTimeout(this.resize_observer_timer);
+                    this.resize_observer_timer = setTimeout(() => {
+                        this.onResize();
+                    }, RESIZE_DEBOUNCE_TIME_MS);
+                }
+            }
+        });
+        this.resize_observer.observe(this.elem);
+    }
+
+    destroyEvents() {
+        /** Destroys all event listeners and observers. */
+        // We can simplify removal of event listeners by firing an AbortController
+        // abort signal. Must pass the signal to any event listeners on creation.
+        if (this.event_abort_controller) {
+            this.event_abort_controller.abort();
+        }
+        if (!isNullOrUndefined(this.resize_observer)) {
+            this.resize_observer.disconnect();
+        }
+        clearTimeout(this.resize_observer_timer);
+        this.resize_observer = null;
+        this.resize_observer_timer = null;
+    }
+
+    onMove(event, prev, handle, next) {
+        /** Handles pointermove events. */
+        const par_dims = this.elem.getBoundingClientRect();
+        const a_dims = prev.elem.getBoundingClientRect();
+        const b_dims = next.elem.getBoundingClientRect();
+        let pos = handle.axis === 0 ? parseInt(event.y) : parseInt(event.x);
+        pos = Math.min(
+            handle.axis === 0 ? parseInt(par_dims.height) : parseInt(par_dims.width),
+            pos
+        );
+        const a_start =
+            handle.axis === 0 ? parseInt(a_dims.top) : parseInt(a_dims.left);
+        const b_end =
+            handle.axis === 0 ? parseInt(b_dims.bottom) : parseInt(b_dims.right);
+
+        let a = pos - Math.floor(handle.pad_px / 2);
+        let b = pos + Math.floor(handle.pad_px / 2);
+
+        let a_lim = a_start + prev.min_size;
+        let b_lim = b_end - next.min_size;
+
+        if (a < a_lim) {
+            a = a_lim;
+            b = a + handle.pad_px;
+        }
+
+        if (b > b_lim) {
+            b = b_lim;
+            a = b - handle.pad_px;
+        }
+
+        prev.setSize(a - a_start);
+        next.setSize(b_end - b);
+    }
+
+    onResize() {
+        /** Resizes grid items on resize observer events. */
+        const curr_dims = this.elem.getBoundingClientRect();
+        const d_w = curr_dims.width - this.prev_dims.width;
+        const d_h = curr_dims.height - this.prev_dims.height;
+
+        // If no change to size, don't proceed.
+        if (d_w === 0 && d_h === 0) {
+            return;
+        }
+
+        if (d_w < 0) {
+            // Width decrease
+            for (const row of this.container.grid) {
+                let rem = Math.abs(d_w);
+                for (const col of row.slice().reverse()) {
+                    const flex_grow = parseInt(col.elem.style.flexGrow);
+                    rem = col.shrink(rem, {limit_to_base: false});
+                    // Shrink causes flexGrow to be set back to default.
+                    // We want to keep the current flex grow setting so we set it back.
+                    col.render({force_flex_grow: flex_grow === 0 ? false : true});
+                    if (rem <= 0) {
+                        break;
+                    }
+                }
+            }
+        } else if (d_w > 0) {
+            // width increase
+            for (const row of this.container.grid) {
+                for (const col of row.slice().reverse()) {
+                    const amt = col.grow(-1, {only_if_flex: true});
+                    if (amt === 0) {
+                        break;
+                    }
+                }
+            }
+        }
+
+        if (d_h < 0) {
+            // height decrease
+            let rem = Math.abs(d_h);
+            for (const row of this.container.rows.slice().reverse()) {
+                const flex_grow = parseInt(row.elem.style.flexGrow);
+                rem = row.shrink(rem, {limit_to_base: false});
+                // Shrink causes flexGrow to be set back to default.
+                // We want to keep the current flex grow setting so we set it back.
+                row.render({force_flex_grow: flex_grow === 0 ? false : true});
+                if (rem <= 0) {
+                    break;
+                }
+            }
+        } else if (d_h > 0) {
+            // height increase
+            for (const row of this.container.rows.slice().reverse()) {
+                if (row.grow(-1, {only_if_flex: true}) === 0) {
+                    break;
+                }
+            }
+        }
+
+        this.prev_dims = curr_dims;
+    }
+
+    show({row_idx, col_idx} = {}) {
+        /** Show a row or column.
+         * Columns require both the row_idx and col_idx.
+         */
+        this.container.show({row_idx: row_idx, col_idx: col_idx});
+        this.container.updateVisibleHandles();
+    }
+
+    hide({row_idx, col_idx} = {}) {
+        /** Hide a row or column.
+         * Columns require both the row_idx and col_idx.
+         */
+        this.container.hide({row_idx: row_idx, col_idx: col_idx});
+        this.container.updateVisibleHandles();
+    }
+
+    toggle({row_idx, col_idx, override} = {}) {
+        /** Toggle visibility of a row or column.
+         * Columns require both the row_idx and col_idx.
+         */
+        this.container.toggle({
+            row_idx: row_idx,
+            col_idx: col_idx,
+            override: override,
+        });
+        this.container.updateVisibleHandles();
+    }
+
+    toggleElem(elem, override) {
+        /** Toggles the nearest ResizeGridItem to the passed element. */
+        isElementThrowError(elem);
+        let _elem = elem.closest('.resize-grid--col');
+        if (isElement(_elem)) {
+            this.toggle({
+                row_idx: _elem.dataset.row,
+                col_idx: _elem.dataset.col,
+                override: override,
+            });
+        } else {
+            _elem = elem.closest('.resize-grid--row');
+            isElementThrowError(_elem);
+            this.toggle({row_idx: _elem.dataset.row, override: override});
+        }
+    }
+}
+
+function resizeGridGetGrid(elem) {
+    /** Returns the nearest ResizeGrid to the passed element. */
+    // Need to find grid element so we can lookup by its id.
+    const grid_elem = elem.closest('.resize-grid');
+    if (!isElement(grid_elem)) {
+        return null;
+    }
+    // Now try to get the actual ResizeGrid instance.
+    const grid = resize_grids[grid_elem.dataset.gridId];
+    if (isNullOrUndefined(grid)) {
+        return null;
+    }
+
+    return grid;
+}
+
+function resizeGridSetup(elem, {id} = {}) {
+    /** Sets up a new ResizeGrid instance for the provided element. */
+    isElementThrowError(elem);
+    if (!isString(id)) {
+        id = _get_unique_id();
+    }
+    const grid = new ResizeGrid(id, elem);
+    grid.setup();
+    resize_grids[id] = grid;
+    return grid;
+}
diff --git a/javascript/utils.js b/javascript/utils.js
index 01c86fc0c..f21fbb0cb 100644
--- a/javascript/utils.js
+++ b/javascript/utils.js
@@ -665,3 +665,27 @@ function waitForVisible(elem, callback) {
     }).observe(elem);
     if (!callback) return new Promise(resolve => callback = resolve);
 }
+
+function cssRelativeUnitToPx(css_value, target) {
+    // https://stackoverflow.com/a/66569574
+    // doesnt work on `%` unit.
+    target = target || document.body;
+    const units = {
+        px: x => x, // no conversion needed here
+        rem: x => x * parseFloat(getComputedStyle(document.documentElement).fontSize),
+        em: x => x * parseFloat(getComputedStyle(target).fontSize),
+        vw: x => x / 100 * window.innerWidth,
+        vh: x => x / 100 * window.innerHeight,
+    };
+
+    const re = new RegExp(`^([-+]?(?:\\d+(?:\\.\\d+)?))(${Object.keys(units).join('|')})$`, 'i');
+    const matches = css_value.toString().trim().match(re);
+    if (matches) {
+        const value = Number(matches[1]);
+        const unit = matches[2].toLocaleLowerCase();
+        if (unit in units) {
+            return units[unit](value);
+        }
+    }
+    return css_value;
+}
diff --git a/modules/shared_options.py b/modules/shared_options.py
index 63cc205a6..8ae1aba0c 100644
--- a/modules/shared_options.py
+++ b/modules/shared_options.py
@@ -267,7 +267,8 @@ options_templates.update(options_section(('extra_networks', "Extra Networks", "s
     "extra_networks_tree_view_default_enabled": OptionInfo(False, "Show the Extra Networks tree view by default").needs_reload_ui(),
     "extra_networks_card_view_default_enabled": OptionInfo(True, "Show the Extra Networks card view by default").needs_reload_ui(),
     "extra_networks_tree_view_show_files": OptionInfo(True, "Show files in tree view.").info("Disabling this option will remove file entries from the tree view and only show directories.").needs_reload_ui(),
-    "extra_networks_tree_view_default_width": OptionInfo(180, "Default width for the Extra Networks directory tree view", gr.Number).needs_reload_ui(),
+    "extra_networks_dirs_view_default_height": OptionInfo(90, "Default height for the Directory Buttons view", gr.Number).info("in pixels").needs_reload_ui(),
+    "extra_networks_tree_view_default_width": OptionInfo(180, "Default width for the Extra Networks directory tree view", gr.Number).info("in pixels").needs_reload_ui(),
     "extra_networks_add_text_separator": OptionInfo(" ", "Extra networks separator").info("extra text to add before <...> when adding extra network to prompt"),
     "ui_extra_networks_tab_reorder": OptionInfo("", "Extra networks tab order").needs_reload_ui(),
     "textual_inversion_print_at_load": OptionInfo(False, "Print a list of Textual Inversion embeddings when loading model"),
diff --git a/modules/ui_extra_networks.py b/modules/ui_extra_networks.py
index 567fbf3cc..d6628a6c3 100644
--- a/modules/ui_extra_networks.py
+++ b/modules/ui_extra_networks.py
@@ -842,6 +842,13 @@ class ExtraNetworksPage:
         tree_view_en = shared.opts.extra_networks_tree_view_default_enabled
         card_view_en = shared.opts.extra_networks_card_view_default_enabled
 
+        dirs_view_row_size = shared.opts.extra_networks_dirs_view_default_height
+        tree_view_size = shared.opts.extra_networks_tree_view_default_width
+        if shared.opts.extra_networks_card_width:
+            card_view_size = shared.opts.extra_networks_card_width
+        else:
+            card_view_size = 50
+
         return self.pane_tpl.format(
             **{
                 "tabname": tabname,
@@ -855,8 +862,14 @@ class ExtraNetworksPage:
                 "btn_dirs_view_data_attributes": "data-selected" if dirs_view_en else "",
                 "btn_tree_view_data_attributes": "data-selected" if tree_view_en else "",
                 "btn_card_view_data_attributes": "data-selected" if card_view_en else "",
-                "tree_view_style": f"flex-basis: {shared.opts.extra_networks_tree_view_default_width}px;",
-                "card_view_style": "flex-grow: 1;",
+                "dirs_view_row_style": f"flex: 0 0 {dirs_view_row_size}px;",
+                "tree_and_card_view_row_style": "flex: 1 0 0px;",  # expand to fill
+                "tree_view_style": f"flex: 0 0 {tree_view_size}px;",
+                "card_view_style": f"flex: 1 0 {card_view_size}px;",
+                "dirs_view_row_data_attributes": "data-min-size=\"5vh\"",
+                "tree_and_card_view_row_data_attributes": "data-min-size=\"5vh\"",
+                "tree_view_data_attributes": "data-min-size=\"10vw\"",
+                "card_view_data_attributes": "data-min-size=\"10vw\"",
                 "dirs_html": dirs_html,
                 "card_list_loading_splash_content": card_list_loading_splash_content,
                 "card_list_no_data_splash_content": card_list_no_data_splash_content,
diff --git a/style.css b/style.css
index 735c4112c..23aa0ddda 100644
--- a/style.css
+++ b/style.css
@@ -1156,6 +1156,8 @@ div.accordions > div.input-accordion.input-accordion-open{
     top: 0.5em;
 }
 
+/* ==== RESIZING EVENT FLAGS ==== */
+
 body.resizing {
     cursor: col-resize !important;
 }
@@ -1164,10 +1166,21 @@ body.resizing * {
     pointer-events: none !important;
 }
 
-body.resizing .resize-handle {
+body.resizing .resize-handle,
+body.resizing .resize-grid--handle {
     pointer-events: initial !important;
 }
 
+body.resizing.resize-grid-col {
+    cursor: col-resize !important;
+}
+
+body.resizing.resize-grid-row {
+    cursor: row-resize !important;
+}
+
+/* ==== RESIZE HANDLE ==== */
+
 .resize-handle {
     position: relative;
     cursor: col-resize;
@@ -1186,6 +1199,78 @@ body.resizing .resize-handle {
     border-left: 1px dashed var(--border-color-primary);
 }
 
+/* ==== RESIZE HANDLE GRID ==== */
+.resize-grid {
+    display: flex;
+    flex-direction: column;
+    width: 100%;
+    height: 100%;
+    /* prevent elements from oversizing the container. */
+    min-width: 0;
+    min-height: 0;
+}
+
+.resize-grid--row {
+	display: flex;
+	flex-direction: row;
+    overflow: hidden;
+    flex-wrap: nowrap;
+    /* prevent elements from oversizing the container. */
+    min-width: 0;
+    min-height: 0;
+}
+
+.resize-grid--col {
+    position: relative;
+    display: flex;
+    flex-direction: column;
+    justify-content: center;
+    align-items: center;
+    overflow: hidden;
+    flex-wrap: nowrap;
+    /* prevent elements from oversizing the container. */
+    min-width: 0;
+    min-height: 0;
+}
+
+.resize-grid--handle {
+    position: relative;
+    height: 100%;
+    width: 100%;
+	z-index: 0;
+	background: transparent;
+}
+
+.resize-grid--handle::after {
+    content: "";
+    position: absolute;
+    z-index: -1;
+}
+
+.resize-grid--row-handle {
+    cursor: row-resize;
+}
+
+.resize-grid--row-handle::after {
+    left: 0;
+    right: 0;
+    top: 50%;
+	transform: translateY(-50%);
+	border-top: 1px dashed var(--border-color-primary);
+}
+
+.resize-grid--col-handle {
+    cursor: col-resize;
+}
+
+.resize-grid--col-handle::after {
+    top: 0;
+    bottom: 0;
+    left: 50%;
+	transform: translateX(-50%);
+	border-left: 1px dashed var(--border-color-primary);
+}
+
 /* ========================= */
 .clusterize-scroll {
     width: 100%;
@@ -1246,18 +1331,18 @@ body.resizing .resize-handle {
 }
 
 .extra-network-content--dirs-view {
-    flex: 0 1 min-content;
-    flex-flow: row wrap;
-    max-height: 20%;
-    gap: var(--spacing-sm);
+    display: block;
+    flex: 1;
     overflow: clip auto;
     border: 1px solid var(--block-border-color);
     padding: var(--spacing-md);
 }
 
-.extra-network-content--tree-and-cards-view {
-    flex: 1;
-    flex-direction: row;
+.extra-network-content--dirs-view > button {
+    margin: var(--spacing-xs) !important;
+}
+
+.extra-network-content--main-view {
     min-height: 0; /* prevent children from oversizing this container */
 }
 
@@ -1493,6 +1578,8 @@ body.resizing .resize-handle {
     grid-gap: var(--spacing-sm);
     place-items: center stretch;
     text-align: center;
+    /* prevents height from changing on overflow */
+    min-width: 0;
 }
 
 .tree-list-item:hover {