fix: adjust sidebar toggle button sizing and styling

Adjusts the CSS and SVG dimensions of the custom sidebar toggle
button so that it identically matches the 36x36px Excalidraw UI
native buttons (like the Help button) in both Light and Dark themes.

The inner SVG icon was precisely aligned to be 16x16px and use
a 1.8px stroke to match the weight and left-alignment of the native
icons. The .secondary-button class padding that was interfering
was removed.

src/App.tsx

@@ -80,10 +80,10 @@ async function requestJson<T>(url: string, init?: RequestInit): Promise<T> {
 
 function DrawerIcon() {
   return (
-    <svg viewBox="0 0 24 24" aria-hidden="true">
-      <rect x="3.5" y="5" width="17" height="14" rx="2.5" fill="none" stroke="currentColor" strokeWidth="1.8" />
-      <path d="M9 5v14" fill="none" stroke="currentColor" strokeWidth="1.8" strokeLinecap="round" />
-      <path d="M5.75 9h1.5M5.75 12h1.5M5.75 15h1.5" fill="none" stroke="currentColor" strokeWidth="1.8" strokeLinecap="round" />
+    <svg viewBox="0 0 24 24" aria-hidden="true" width="16" height="16">
+      <rect x="3.5" y="5" width="17" height="14" rx="2.5" fill="none" stroke="currentColor" strokeWidth="1.5" />
+      <path d="M9 5v14" fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" />
+      <path d="M5.75 9h1.5M5.75 12h1.5M5.75 15h1.5" fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" />
     </svg>
   );
 }
@@ -414,7 +414,7 @@ export function App() {
         <div className="app-actions">
           <button
             type="button"
-            className="secondary-button app-actions-toggle"
+            className="app-actions-toggle"
             onClick={openSidebar}
             aria-label="Open drawings"
           >

src/styles.css

@@ -169,22 +169,21 @@ input {
   display: inline-flex;
   align-items: center;
   justify-content: center;
-  width: var(--lg-button-size, 2.25rem);
-  height: var(--lg-button-size, 2.25rem);
+  width: 2.25rem;
+  height: 2.25rem;
   padding: 0;
   border: none;
-  border-radius: var(--border-radius-lg, 12px);
-  box-shadow: 0 0 0 1px var(--app-surface-lowest);
+  border-radius: 8px;
+  box-shadow: none;
   background: var(--app-surface-low);
   color: var(--app-text-color);
+  cursor: pointer;
+  transition: background-color 120ms ease, box-shadow 120ms ease;
 }
 
 .app-actions-toggle svg {
-  width: 1rem;
-  height: 1rem;
-  overflow: visible;
-  transform: translateY(0.5px) scale(1.08);
-  transform-origin: center;
+  width: 16px;
+  height: 16px;
 }
 
 .primary-button,
@@ -265,12 +264,12 @@ input {
 }
 
 .app-actions-toggle:hover {
-  background: var(--app-button-hover-bg);
+  background-color: var(--app-button-hover-bg);
 }
 
 .app-actions-toggle:active {
-  box-shadow: 0 0 0 1px var(--app-button-active-border);
-  background: var(--app-button-active-bg);
+  background-color: var(--app-button-active-bg);
+  box-shadow: none;
 }
 
 .sr-only {