feat(01-04): fix CSS variable naming — add --accent as canonical source of truth

- Add --accent: #00ffff as canonical variable in :root
- Make --border-bright and --text-accent aliases of var(--accent)
- Add .device-form styles: flex column, gap, border-top separator
- Add .device-remove styles: borderless, hover red
- Update .device-row to flex row with justify-content: space-between for remove button
- Add .device-row-info for name/metadata stack within each row

lightsync/frontend/style.css

@@ -3,10 +3,11 @@
     --bg-panel:      #0f0f0f;
     --bg-panel-dark: #080808;
     --border-dim:    #1a4a4a;
-    --border-bright: #00ffff;
+    --accent:        #00ffff;
+    --border-bright: var(--accent);
     --text-primary:  #cccccc;
     --text-dim:      #555555;
-    --text-accent:   #00ffff;
+    --text-accent:   var(--accent);
     --text-warning:  #ff6600;
     --font-mono:     'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
     --font-size:     13px;
@@ -142,15 +143,23 @@ body {
 /* Device list rows */
 .device-row {
     display: flex;
-    flex-direction: column;
+    align-items: center;
+    justify-content: space-between;
     padding: 6px 0;
     border-bottom: 1px solid var(--bg-panel-dark);
-    gap: 2px;
+    gap: 8px;
 }
 .device-row:last-child {
     border-bottom: none;
 }
 
+.device-row-info {
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+    min-width: 0;
+}
+
 /* Form elements */
 input, select, button {
     background: var(--bg-panel);
@@ -167,3 +176,36 @@ button:hover {
     color: var(--text-accent);
     cursor: pointer;
 }
+
+/* Device form */
+.device-form {
+    display: flex;
+    flex-direction: column;
+    gap: 4px;
+    padding: 8px 12px;
+    border-top: 1px solid var(--border-dim);
+}
+
+.device-form button[type="submit"] {
+    margin-top: 4px;
+    text-transform: uppercase;
+    letter-spacing: 0.08em;
+}
+
+/* Device remove button */
+.device-remove {
+    background: none;
+    border: none;
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: 16px;
+    cursor: pointer;
+    padding: 0 4px;
+    line-height: 1;
+    flex-shrink: 0;
+}
+
+.device-remove:hover {
+    color: #ff3333;
+    border: none;
+}