Return all widths and heights in the resize done event.

tp-hsplitter.js

@@ -124,17 +124,28 @@ class TpHSplitter extends LitElement {
     document.body.style['userSelect'] = '';
     this.dragging = false;
 
-    let finalHeight;
+    let finalTopHeight;
     if (this.lateResize && this._bufferedDelta) {
-      finalHeight = this._topHeight + this._bufferedDelta;
+      finalTopHeight = this._topHeight + this._bufferedDelta;
       this.splitter.style.transform = '';
-      this.style.gridTemplateRows = `${finalHeight}px 5px 1fr`;
+      this.style.gridTemplateRows = `${finalTopHeight}px 5px 1fr`;
       this._bufferedDelta = 0;
     } else {
-      finalHeight = this.top.offsetHeight;
+      finalTopHeight = this.top.offsetHeight;
     }
 
-    this.dispatchEvent(new CustomEvent('resize-done', { detail: finalHeight, bubbles: true, composed: true }));
+    // Calculate bottom height
+    const splitterWidth = parseInt(getComputedStyle(this).getPropertyValue('--tp-splitter-width')) || 5;
+    const finalBottomHeight = this.offsetHeight - finalTopHeight - splitterWidth;
+
+    this.dispatchEvent(new CustomEvent('resize-done', { 
+      detail: { 
+        topHeight: finalTopHeight, 
+        bottomHeight: finalBottomHeight 
+      }, 
+      bubbles: true, 
+      composed: true 
+    }));
   }
 
   _resize(e) {