/* ══════════════════════════════════════
   controls.css — Top header bar + buttons
   ══════════════════════════════════════ */

/* ── Header 條：無邊框，只靠漸層壓暗 ── */
.control-panel {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 2000;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  padding: 0 20px;
  gap: 10px;
  /* 向下漸層，捲動內容經過時被自然壓暗 */
  background: linear-gradient(
    to bottom,
    rgba(3, 5, 16, 0.78) 0%,
    rgba(3, 5, 16, 0.0)  100%
  );
  /* 讓點擊穿透背景，按鈕自己恢復 */
  pointer-events: none;
}
.control-panel > * { pointer-events: auto; }

[data-theme="light"] .control-panel {
  background: linear-gradient(
    to bottom,
    rgba(240, 244, 250, 0.88) 0%,
    rgba(240, 244, 250, 0.0)  100%
  );
}

/* ── 按鈕：縮小一點配合 header 高度 ── */
.control-btn {
  width: 42px; height: 42px; border-radius: 999px;
  border: 1.5px solid var(--accent-color);
  background: var(--glass-bg); color: var(--accent-color);
  font-size: 1.1rem;
  display: inline-flex; align-items: center; justify-content: center;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: transform 0.4s var(--ease-pop), box-shadow 0.4s var(--ease-smooth),
              background 0.4s var(--ease-smooth), color 0.4s var(--ease-smooth),
              border-color 0.4s var(--ease-smooth);
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.25);
  position: relative; overflow: hidden; cursor: pointer;
}
.control-btn::before {
  content: ""; position: absolute; inset: 0;
  background: var(--accent-color); opacity: 0;
  transition: opacity 0.3s var(--ease-smooth);
}
.control-btn i,
.control-btn span {
  position: relative; z-index: 1;
  transition: transform 0.4s var(--ease-pop), color 0.4s var(--ease-smooth);
}
.control-btn:hover {
  transform: scale(1.12) rotate(4deg);
  box-shadow: 0 0 28px color-mix(in oklab, var(--accent-color) 70%, transparent);
}
.control-btn:hover::before { opacity: 1; }
.control-btn:hover i { color: var(--bg-color); transform: rotate(-4deg) scale(1.08); }
.control-btn:hover span { color: var(--bg-color); transform: scale(1.08); }

/* ══════════════════════════════════════
   回頂端按鈕 (Back to Top)
   ══════════════════════════════════════ */
.back-to-top {
  position: fixed;
  bottom: 40px; right: 30px;
  width: 46px; height: 46px;
  border-radius: 50%;
  background: var(--glass-bg);
  border: 2px solid var(--accent-color);
  color: var(--accent-color);
  font-size: 1.1rem;
  display: flex; align-items: center; justify-content: center;
  cursor: pointer;
  opacity: 0; visibility: hidden;
  transform: translateY(30px);
  transition: all 0.5s var(--ease-pop);
  z-index: 1500;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
}
.back-to-top.show { opacity: 1; visibility: visible; transform: translateY(0); }
.back-to-top:hover {
  background: var(--accent-color); color: var(--bg-color);
  box-shadow: 0 0 25px var(--accent-color);
  transform: translateY(-8px) scale(1.1);
}

@media (max-width: 768px) {
  .control-panel { height: 50px; padding: 0 12px; gap: 8px; }
  .control-btn   { width: 38px; height: 38px; font-size: 1rem; }
  .back-to-top   { bottom: 25px; right: 16px; width: 40px; height: 40px; font-size: 1rem; }
}