Merge branch 'dev'

- Move tab row up 1px (top: 55px) to overlap header border, eliminating gap
- Minimize toggle now hides header + tab row + subnav (was leaving subnav visible)
- Floating restore button (top-right, semi-transparent) when headers minimized
- Smooth transition on subnav hide/show

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

website/public/shell.css

@@ -73,7 +73,7 @@ body.rspace-banner-visible .rstack-header {
   top: 36px;
 }
 body.rspace-banner-visible .rstack-tab-row {
-  top: 92px; /* 36px banner + 56px header */
+  top: 91px; /* 36px banner + 56px header - 1px overlap */
 }
 body.rspace-banner-visible #app {
   padding-top: 128px; /* 36px banner + 92px normal */
@@ -209,7 +209,7 @@ body.rspace-banner-visible #app {
 
 .rstack-tab-row {
   position: fixed;
-  top: 56px;
+  top: 55px; /* overlap header border by 1px to close gap */
   left: 0;
   right: 0;
   z-index: 9998;
@@ -224,7 +224,7 @@ body.rspace-banner-visible #app {
 /* ── Main content area ── */
 
 #app {
-  padding-top: 92px; /* Below fixed header (56px) + tab row (36px) */
+  padding-top: 91px; /* Below fixed header (56px) + tab row (36px) - 1px overlap */
   height: 100vh;
   display: flex;
   flex-direction: column;
@@ -604,7 +604,7 @@ body.rspace-headers-minimized .rapp-minimize-btn svg {
   transform: rotate(180deg);
 }
 
-/* Minimized state: hide header + tab row, subnav becomes thin restore strip */
+/* Minimized state: hide all 3 header bars, floating restore button */
 body.rspace-headers-minimized .rstack-header {
   transform: translateY(-100%);
   pointer-events: none;
@@ -613,17 +613,36 @@ body.rspace-headers-minimized .rstack-tab-row {
   transform: translateY(-100%);
   pointer-events: none;
 }
+body.rspace-headers-minimized .rapp-subnav {
+  transform: translateY(-100%);
+  pointer-events: none;
+  opacity: 0;
+}
 body.rspace-headers-minimized #app {
   padding-top: 0;
 }
 body.rspace-headers-minimized #app.canvas-layout {
   padding-top: 0;
 }
-body.rspace-headers-minimized .rapp-subnav {
+/* Floating restore button when all headers minimized */
+body.rspace-headers-minimized .rapp-minimize-btn {
+  position: fixed;
+  top: 6px;
+  right: 12px;
+  z-index: 10000;
+  pointer-events: auto;
+  width: 28px;
   height: 28px;
-  padding: 2px 8px;
-  overflow: hidden;
-  justify-content: flex-end;
+  background: var(--rs-glass-bg);
+  backdrop-filter: blur(12px);
+  -webkit-backdrop-filter: blur(12px);
+  border: 1px solid var(--rs-border);
+  border-radius: 8px;
+  opacity: 0.6;
+  transition: opacity 0.15s;
+}
+body.rspace-headers-minimized .rapp-minimize-btn:hover {
+  opacity: 1;
 }
 
 /* Smooth transitions for header minimize/restore */
@@ -633,6 +652,9 @@ body.rspace-headers-minimized .rapp-subnav {
 .rstack-tab-row {
   transition: margin-left 0.25s ease, left 0.25s ease, transform 0.25s ease, top 0.3s ease-out;
 }
+.rapp-subnav {
+  transition: transform 0.25s ease, opacity 0.25s ease;
+}
 #app {
   transition: margin-left 0.25s ease, left 0.25s ease, padding-top 0.3s ease-out;
 }
@@ -650,6 +672,12 @@ body.rspace-headers-minimized .rapp-subnav {
     overflow: hidden;
     transform: none;
   }
+  body.rspace-headers-minimized .rapp-subnav {
+    max-height: 0;
+    overflow: hidden;
+    transform: none;
+    opacity: 0;
+  }
 }
 
 /* ── Flex gap fallback for Safari <14.1 ── */