Add cleanly named methods to set the dimentions of both panels for both splitters.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@tp/tp-splitter",
-  "version": "2.1.1",
+  "version": "2.2.0",
   "description": "",
   "main": "tp-splitter.js",
   "scripts": {

tp-hsplitter.js

@@ -106,10 +106,14 @@ class TpHSplitter extends LitElement {
     document.body.style['userSelect'] = '';
   }
 
-  setHeight(height) {
+  setTopHeight(height) {
     this.style.gridTemplateRows = `${height} var(--tp-splitter-width, 5px) 1fr`;
   }
 
+  setBottomHeight(height) {
+    this.style.gridTemplateRows = `1fr var(--tp-splitter-width, 5px) ${height}`;
+  }
+
   _enableDrag(e) {
     e.preventDefault();
     if (this.splitter && e.pointerId != null) {