Add custom layout creation.

src/style.css

@@ -171,6 +171,67 @@
   border-color: #b29df5;
 }
 
+/* Saved-layout menu, hanging off the sidebar header. */
+.vtabs-layout-menu {
+  min-width: 260px;
+}
+
+.vtabs-layout-menu button {
+  padding: 4px 8px;
+  border-radius: 6px;
+}
+
+.vtabs-layout-empty {
+  padding: 8px;
+  color: #8f87a3;
+  font-size: 0.9em;
+}
+
+/* Layout dialogs: opening one, and saving the current tab as one. */
+.vtabs-dialog {
+  background-color: #16141c;
+}
+
+.vtabs-dialog-content {
+  padding: 16px;
+}
+
+.vtabs-dialog-actions {
+  padding: 12px 16px;
+  border-top: 1px solid #262133;
+}
+
+.vtabs-dialog-heading {
+  margin-top: 8px;
+  font-weight: bold;
+  color: #ded7ef;
+}
+
+.vtabs-dialog-label {
+  color: #b6afc7;
+}
+
+.vtabs-dialog-sublabel {
+  font-size: 0.88em;
+  color: #8f87a3;
+}
+
+.vtabs-dialog-hint {
+  font-size: 0.85em;
+  color: #8f87a3;
+}
+
+.vtabs-dialog-error {
+  color: #f2a0a0;
+}
+
+/* Each captured pane in the save dialog, so the sections read apart. */
+.vtabs-dialog-pane {
+  padding: 8px;
+  border: 1px solid #2a2536;
+  border-radius: 8px;
+}
+
 /* Divider between panes. Wide enough to grab without hunting for it. */
 .vtabs-view paned > separator {
   background-color: #0f0d14;