/* ==========================================================================
   魔方还原大师 —— 样式
   ========================================================================== */
:root {
  --bg: #070b16;
  --bg2: #0d1426;
  --card: rgba(20, 28, 48, 0.72);
  --card-solid: #141c30;
  --line: rgba(148, 163, 184, 0.16);
  --txt: #e8eefc;
  --dim: #93a3c0;
  --cyan: #38bdf8;
  --green: #4ade80;
  --amber: #fbbf24;
  --violet: #818cf8;
  --radius: 16px;
  --shadow: 0 18px 40px -18px rgba(0, 0, 0, 0.85);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  background: var(--bg);
  color: var(--txt);
  font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  -webkit-font-smoothing: antialiased;
  overscroll-behavior: none;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background:
    radial-gradient(900px 600px at 12% -5%, rgba(56, 189, 248, 0.16), transparent 60%),
    radial-gradient(800px 520px at 92% 8%, rgba(129, 140, 248, 0.16), transparent 62%),
    radial-gradient(700px 500px at 50% 110%, rgba(74, 222, 128, 0.10), transparent 60%),
    linear-gradient(180deg, #070b16 0%, #0a1020 60%, #070b16 100%);
  z-index: -2;
}

.app {
  height: 100%;
  display: flex;
  flex-direction: column;
  min-height: 100dvh;
}

/* ---------- 顶栏 ---------- */
.topbar {
  flex: none;
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 12px 20px;
  border-bottom: 1px solid var(--line);
  background: rgba(10, 16, 32, 0.6);
  backdrop-filter: blur(14px);
  flex-wrap: wrap;
}

.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; letter-spacing: 0.5px; }
.brand .logo { font-size: 24px; filter: drop-shadow(0 4px 10px rgba(56, 189, 248, 0.5)); }
.brand .title { font-size: 18px; background: linear-gradient(90deg, #e8eefc, #7dd3fc); -webkit-background-clip: text; background-clip: text; color: transparent; }

.sizes {
  display: flex;
  gap: 4px;
  padding: 4px;
  background: rgba(148, 163, 184, 0.10);
  border: 1px solid var(--line);
  border-radius: 12px;
}
.size-btn {
  border: 0;
  background: transparent;
  color: var(--dim);
  font: inherit;
  font-size: 14px;
  font-weight: 600;
  padding: 7px 14px;
  border-radius: 9px;
  cursor: pointer;
  transition: all 0.18s ease;
}
.size-btn:hover { color: var(--txt); background: rgba(148, 163, 184, 0.12); }
.size-btn.is-active {
  color: #06121f;
  background: linear-gradient(135deg, #7dd3fc, #38bdf8);
  box-shadow: 0 6px 16px -6px rgba(56, 189, 248, 0.8);
}

.stats { display: flex; gap: 10px; margin-left: auto; }
.stat {
  min-width: 76px;
  padding: 6px 12px;
  border-radius: 12px;
  background: var(--card);
  border: 1px solid var(--line);
  text-align: center;
}
.stat span { display: block; font-size: 11px; color: var(--dim); letter-spacing: 1px; }
.stat b { font-size: 17px; font-variant-numeric: tabular-nums; }

/* ---------- 主区 ---------- */
.stage {
  flex: 1;
  min-height: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 340px;
}

.canvas-wrap {
  position: relative;
  min-height: 0;
  min-width: 0;
}
#stage {
  display: block;
  width: 100%;
  height: 100%;
  touch-action: none;
  cursor: grab;
}
#stage.dragging { cursor: grabbing; }

.badge {
  position: absolute;
  left: 18px;
  top: 16px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 1px;
  color: var(--dim);
  background: var(--card);
  border: 1px solid var(--line);
  padding: 6px 12px;
  border-radius: 999px;
  pointer-events: none;
}

.toast {
  position: absolute;
  left: 50%;
  top: 18px;
  transform: translate(-50%, -14px);
  padding: 9px 18px;
  border-radius: 999px;
  background: rgba(11, 18, 34, 0.92);
  border: 1px solid var(--line);
  font-size: 13px;
  color: var(--txt);
  opacity: 0;
  pointer-events: none;
  transition: all 0.28s cubic-bezier(0.2, 0.8, 0.2, 1);
  box-shadow: var(--shadow);
  max-width: 80%;
  text-align: center;
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }

.errbar {
  position: absolute;
  left: 12px; right: 12px; top: 12px;
  padding: 10px 14px;
  border-radius: 12px;
  background: rgba(120, 20, 30, 0.92);
  border: 1px solid rgba(255, 120, 120, 0.5);
  color: #ffe4e4;
  font-size: 12px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  z-index: 20;
  max-height: 34%;
  overflow: auto;
  white-space: pre-wrap;
}
.errbar[hidden] { display: none; }

/* ---------- 自动还原控制条 ---------- */
.solve-bar {
  position: absolute;
  left: 14px;
  right: 14px;
  bottom: 14px;
  z-index: 8;
  padding: 10px 12px 8px;
  border-radius: 14px;
  background: rgba(11, 18, 34, 0.92);
  border: 1px solid rgba(56, 189, 248, 0.32);
  box-shadow: 0 18px 40px -18px rgba(0, 0, 0, 0.9);
  backdrop-filter: blur(10px);
}
.solve-bar[hidden] { display: none; }
.solve-head { display: flex; align-items: center; gap: 10px; margin-bottom: 8px; flex-wrap: wrap; }
.solve-state { font-size: 13px; font-weight: 700; color: #7dd3fc; }
.solve-state.paused { color: var(--amber); }
.solve-step { font-size: 12px; color: var(--dim); font-variant-numeric: tabular-nums; }
.solve-move {
  font-size: 15px; font-weight: 800; min-width: 30px; text-align: center;
  padding: 1px 8px; border-radius: 7px;
  background: linear-gradient(135deg, #38bdf8, #6366f1); color: #05101f;
}
.solve-btns { margin-left: auto; display: flex; gap: 6px; }
.mini {
  border: 1px solid var(--line);
  background: rgba(148, 163, 184, 0.12);
  color: var(--txt);
  font: inherit; font-size: 12px; font-weight: 600;
  padding: 5px 12px; border-radius: 8px; cursor: pointer;
  transition: background 0.15s ease, transform 0.1s ease;
}
.mini:hover { background: rgba(148, 163, 184, 0.24); }
.mini:active { transform: scale(0.96); }
.mini.danger { border-color: rgba(251, 191, 36, 0.5); color: #fde68a; }
.mini.danger:hover { background: rgba(251, 191, 36, 0.18); }
.solve-steps {
  display: flex; flex-wrap: wrap; gap: 4px;
  margin-top: 8px; max-height: 58px; overflow-y: auto;
  font-size: 11.5px; line-height: 1.5;
}
.solve-steps i {
  font-style: normal; padding: 1px 6px; border-radius: 6px;
  background: rgba(148, 163, 184, 0.12); color: var(--dim);
  font-variant-numeric: tabular-nums;
}
.solve-steps i.done { color: #86efac; background: rgba(74, 222, 128, 0.12); }
.solve-steps i.now {
  color: #05101f; background: #7dd3fc; font-weight: 800;
  box-shadow: 0 0 0 2px rgba(125, 211, 252, 0.28);
}

.overlay {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: rgba(5, 9, 20, 0.55);
  backdrop-filter: blur(3px);
  z-index: 5;
}
.overlay[hidden] { display: none; }
.overlay-card {
  width: min(340px, 82%);
  padding: 26px;
  border-radius: var(--radius);
  background: var(--card-solid);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  text-align: center;
}
.spinner {
  width: 40px; height: 40px;
  margin: 0 auto 14px;
  border-radius: 50%;
  border: 3px solid rgba(125, 211, 252, 0.2);
  border-top-color: var(--cyan);
  animation: spin 0.9s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.overlay-text { font-size: 14px; color: var(--txt); margin-bottom: 14px; }
.progress { height: 7px; border-radius: 999px; background: rgba(148, 163, 184, 0.18); overflow: hidden; }
.progress-bar { height: 100%; width: 0%; border-radius: 999px; background: linear-gradient(90deg, #38bdf8, #4ade80); transition: width 0.12s linear; }

.success {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: rgba(5, 12, 20, 0.5);
  z-index: 6;
  animation: fade 0.3s ease;
}
.success[hidden] { display: none; }
@keyframes fade { from { opacity: 0; } to { opacity: 1; } }
.success-inner {
  text-align: center;
  padding: 30px 40px;
  border-radius: 20px;
  background: var(--card-solid);
  border: 1px solid rgba(74, 222, 128, 0.35);
  box-shadow: 0 24px 60px -20px rgba(74, 222, 128, 0.5);
}
.success-title { font-size: 24px; font-weight: 800; color: var(--green); }
.success-sub { font-size: 13px; color: var(--dim); margin: 8px 0 18px; }

/* ---------- 侧栏 ---------- */
.panel {
  border-left: 1px solid var(--line);
  background: rgba(11, 17, 32, 0.55);
  backdrop-filter: blur(14px);
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  overflow-y: auto;
}

.actions { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; }
.actions.row2 { grid-template-columns: repeat(3, 1fr); }

.btn {
  border: 1px solid var(--line);
  background: rgba(148, 163, 184, 0.10);
  color: var(--txt);
  font: inherit;
  font-size: 13px;
  font-weight: 600;
  padding: 11px 8px;
  border-radius: 12px;
  cursor: pointer;
  transition: transform 0.12s ease, background 0.18s ease, box-shadow 0.18s ease;
  white-space: nowrap;
}
.btn:hover { background: rgba(148, 163, 184, 0.18); transform: translateY(-1px); }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; transform: none; }
.btn.small { padding: 9px 6px; font-size: 12px; }
.btn.primary {
  background: linear-gradient(135deg, #38bdf8, #6366f1);
  border-color: transparent;
  color: #05101f;
  box-shadow: 0 10px 22px -12px rgba(99, 102, 241, 0.9);
}
.btn.accent {
  background: linear-gradient(135deg, #fbbf24, #f97316);
  border-color: transparent;
  color: #241100;
  box-shadow: 0 10px 22px -12px rgba(251, 191, 36, 0.9);
}
.btn.ghost { background: transparent; margin-top: 12px; width: 100%; }

.hint-card {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
  padding: 12px 14px;
}
.hint-card[data-empty="0"] { border-color: rgba(56, 189, 248, 0.45); box-shadow: 0 0 0 1px rgba(56, 189, 248, 0.12) inset; }
.hint-head {
  display: flex; justify-content: space-between; align-items: center;
  font-size: 12px; color: var(--dim); letter-spacing: 1px; margin-bottom: 8px;
}
.hint-src { color: var(--cyan); }
.hint-main { font-size: 15px; font-weight: 700; line-height: 1.55; }
.hint-main .mv {
  display: inline-block;
  min-width: 34px;
  text-align: center;
  padding: 2px 8px;
  margin: 0 2px;
  border-radius: 8px;
  background: linear-gradient(135deg, #38bdf8, #6366f1);
  color: #05101f;
  font-size: 16px;
  font-weight: 800;
}
.hint-steps { margin-top: 8px; font-size: 12px; color: var(--dim); line-height: 1.9; word-break: break-all; }
.hint-steps b { color: #bae6fd; font-weight: 700; }
.hint-steps span { opacity: 0.65; }

.pad-wrap { border: 1px solid var(--line); border-radius: var(--radius); background: var(--card); padding: 12px; }
.pad-title { font-size: 12px; color: var(--dim); margin-bottom: 10px; letter-spacing: 0.5px; }
.pad-title em { font-style: normal; opacity: 0.7; }
.pad {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  gap: 6px;
  aspect-ratio: 1 / 1;
  max-width: 240px;
  margin: 0 auto;
}
.pad-cell { display: flex; }
.pad-btn {
  flex: 1;
  display: flex;
  flex-direction: column;
  border: 1px solid var(--line);
  border-radius: 10px;
  overflow: hidden;
  cursor: pointer;
  background: rgba(148, 163, 184, 0.08);
  font: inherit;
  padding: 0;
  transition: filter 0.15s ease, transform 0.1s ease;
}
.pad-btn:hover { filter: brightness(1.35); }
.pad-btn:active { transform: scale(0.96); }
.pad-btn .half {
  flex: 1;
  display: flex; align-items: center; justify-content: center;
  font-size: 14px; font-weight: 800; color: var(--txt);
}
.pad-btn .half + .half { border-top: 1px dashed rgba(148, 163, 184, 0.25); font-size: 12px; color: var(--dim); }
.pad-btn .dot { width: 8px; height: 8px; border-radius: 50%; margin-right: 6px; }
.pad-btn .lab { display: flex; align-items: center; }
.pad-extra { display: flex; gap: 6px; justify-content: center; margin-top: 8px; }
.pad-extra .pad-btn { flex-direction: row; }
.pad-extra .pad-btn .half { padding: 0 12px; }

.help { font-size: 11.5px; color: var(--dim); line-height: 1.9; margin-top: auto; opacity: 0.85; }
.help b { color: #cbd5f5; font-weight: 600; }

/* ---------- 响应式 ---------- */
@media (max-width: 960px) {
  .stage { grid-template-columns: 1fr; grid-template-rows: minmax(320px, 1fr) auto; }
  .panel { border-left: 0; border-top: 1px solid var(--line); max-height: 48dvh; }
  .topbar { padding: 10px 12px; gap: 10px; }
  .brand .title { font-size: 15px; }
  .stats { gap: 6px; }
  .stat { min-width: 62px; padding: 5px 8px; }
  .stat b { font-size: 15px; }
  .pad { max-width: 210px; }
}

@media (max-width: 520px) {
  .brand .title { display: none; }
  .size-btn { padding: 6px 10px; font-size: 13px; }
  .actions { grid-template-columns: repeat(3, 1fr); }
  .btn { font-size: 12px; padding: 10px 4px; }
}