style: Adjust toolbar height calculation and update workspace button visibility

src/browser/base/content/ZenStartup.mjs

@@ -75,7 +75,7 @@
       const toolbarRect = toolbarItems.getBoundingClientRect();
       let height = toolbarRect.height;
       // -5 for the controls padding
-      let totalHeight = toolbarRect.height - (this.contentElementSeparation) - 45;
+      let totalHeight = toolbarRect.height - (this.contentElementSeparation * 2) - 5;
       // remove the height from other elements that aren't hidden
       const otherElements = document.querySelectorAll('#tabbrowser-tabs > *:not([hidden="true"])');
       for (let tab of otherElements) {

src/browser/base/content/zen-styles/zen-workspaces.css

@@ -8,9 +8,7 @@
   position: relative;
 
   &[dont-show='true'] {
-    /* We need to keep the button visible to keep the toolbar layout */
-    opacity: 0;
-    pointer-events: none;
+    display: none !important;
   }
 
   &:not([as-button='true']) {