simplify CSS rules for brush editor overflow

static/index.css

@@ -41,13 +41,10 @@ main {
 
         &>.right {
             grid-column: right / right;
-            height: 100%;
+            height: fit-content;
             min-height: 0;
             max-height: 100%;
 
-            &>.right-content {
-                max-height: 100%;
-
             display: flex;
             flex-direction: row;
             justify-content: stretch;
@@ -64,7 +61,6 @@ main {
             }
         }
     }
-    }
 
     &>rkgk-canvas-renderer {
         width: 100%;

static/index.html

@@ -51,7 +51,6 @@
                     <a href="/docs/rkgk.html">Manual</a>
                 </div>
                 <div class="right">
-                    <div class="right-content">
                     <rkgk-resize-handle
                         data-direction="vertical"
                         data-target="panels-overlay"
@@ -60,7 +59,6 @@
                     <rkgk-brush-editor></rkgk-brush-editor>
                 </div>
             </div>
-            </div>
 
             <rkgk-welcome>
                 <dialog name="welcome-dialog" class="rkgk-panel">