Refine themes, add sidebar controls, and theme docs

Refined: softer dark-mode link color (#a0c4e8), fix export button
vertical alignment with inline-flex, tighten settings page spacing
(reduce gaps from 3rem to 1.5rem).

Terminal: switch accent from cyan to green (#4ae54a dark / #1a7a2e
light), add proper light mode with pale steel background, scanlines
only in dark mode.

Sidebar: add quick-access controls in footer — moon/sun icon toggles
light/dark, circle icon cycles through style themes showing current
name. Both update reactively on state change.

Add THEMES.md with full documentation on creating new themes:
variable reference, selector guide, light/dark mode tips, and the
registration process.

https://claude.ai/code/session_01Jv3c8GdaDQMm5WYwHUJMVe

1 files changed, 41 insertions, 0 deletions

diff --git a/frontend-vanilla/src/style.css b/frontend-vanilla/src/style.css
index e9512b7..3061948 100644
--- a/frontend-vanilla/src/style.css
+++ b/frontend-vanilla/src/style.css
@@ -215,6 +215,47 @@ html {
   opacity: 1;
 }
 
+/* Quick controls row in sidebar footer */
+.sidebar-quick-controls {
+  display: flex;
+  gap: 0.4rem;
+  margin-bottom: 0.25rem;
+}
+
+.sidebar-icon-btn {
+  background: none;
+  border: none;
+  cursor: pointer;
+  font-size: 0.75rem;
+  padding: 0.3rem 0.6rem;
+  border-radius: 6px;
+  color: var(--text-color);
+  opacity: 0.5;
+  transition: opacity 0.15s, background 0.15s;
+  font-family: var(--font-sans);
+  text-transform: none;
+  font-weight: 500;
+  height: auto;
+  line-height: 1.3;
+}
+
+.sidebar-icon-btn:hover {
+  opacity: 1;
+  background: rgba(255, 255, 255, 0.08);
+  border: none;
+}
+
+.theme-dark .sidebar-icon-btn {
+  color: rgba(0, 0, 0, 0.87);
+  border: none;
+  background: none;
+}
+
+.theme-dark .sidebar-icon-btn:hover {
+  background: rgba(0, 0, 0, 0.06);
+  border: none;
+}
+
 /* Main Content area - always fills full width (sidebar overlays) */
 .main-content {
   width: 100%;