:root {
  color-scheme: light;
  --ink: #222332;
  --muted: #9a9aa5;
  --mint: #b9fff2;
  --mint-active: #93f4e4;
  --orange: #ff5b28;
  --cream: #fff5f0;
  --yellow: #ffc30d;
  --line: #ececf1;
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

body {
  margin: 0;
  min-height: 100vh;
  min-height: 100dvh;
  background: #fff;
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Microsoft YaHei", sans-serif;
}

button {
  border: 0;
  font: inherit;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.app {
  width: min(100vw, 430px);
  min-height: 100vh;
  min-height: 100dvh;
  margin: 0 auto;
  padding: clamp(34px, 6dvh, 64px) clamp(18px, 5vw, 28px) 28px;
  display: flex;
  flex-direction: column;
}

.topbar {
  display: grid;
  grid-template-columns: 48px 1fr auto;
  align-items: center;
  gap: 12px;
  min-height: 80px;
}

.icon-btn {
  width: 44px;
  height: 44px;
  background: transparent;
  position: relative;
}

.back-btn span {
  display: block;
  width: 20px;
  height: 20px;
  border-left: 6px solid var(--ink);
  border-bottom: 6px solid var(--ink);
  transform: rotate(45deg);
  margin-left: 12px;
}

.stage {
  display: flex;
  align-items: baseline;
  gap: 10px;
  font-size: clamp(24px, 6vw, 32px);
  font-weight: 700;
  white-space: nowrap;
}

.stage strong {
  font-size: 1em;
}

.muted {
  color: var(--muted);
  font-weight: 500;
}

.actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.mini-btn,
.answer-btn {
  width: 68px;
  height: 68px;
  border-radius: 10px;
  display: grid;
  place-items: center;
  gap: 0;
  box-shadow: 0 0 0 2px rgba(30, 31, 44, 0.08);
}

.mini-btn {
  background: #fff;
}

.answer-btn {
  background: var(--yellow);
  color: #9d5b00;
  box-shadow: 0 8px 20px rgba(255, 195, 13, 0.28);
}

.reset-icon {
  font-size: 36px;
  line-height: 28px;
}

.bulb {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  background: #fff;
  color: var(--orange);
  font-weight: 900;
  line-height: 1;
}

.mini-btn small,
.answer-btn small {
  font-size: 18px;
  font-weight: 700;
  line-height: 1;
}

.game-view {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  gap: clamp(16px, 3dvh, 28px);
  padding-top: clamp(34px, 7dvh, 72px);
  padding-bottom: clamp(22px, 5dvh, 54px);
}

.message {
  min-height: 48px;
  text-align: center;
  color: var(--orange);
  font-size: clamp(16px, 4vw, 18px);
  font-weight: 700;
  line-height: 1.35;
  display: grid;
  place-items: center;
}

.tiles {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(10px, 3.2vw, 14px);
}

.tile {
  aspect-ratio: 1 / 1;
  border-radius: clamp(20px, 6vw, 28px);
  background: var(--mint);
  color: #202133;
  font-size: clamp(54px, 19vw, 86px);
  font-weight: 750;
  display: grid;
  place-items: center;
  transition:
    transform 0.15s ease,
    background 0.15s ease,
    box-shadow 0.15s ease;
}

.tile[data-used="true"] {
  background: #edf0f2;
  color: #aeb3ba;
  box-shadow: inset 0 0 0 2px #e2e5e8;
  pointer-events: none;
}

.tile.selected {
  background: var(--mint-active);
  transform: scale(0.97);
  box-shadow: inset 0 0 0 5px rgba(21, 161, 137, 0.18);
}

.tile .expr {
  padding: 10px;
  font-size: clamp(20px, 6.5vw, 30px);
  text-align: center;
  overflow-wrap: anywhere;
}

.expression {
  min-height: 44px;
  display: grid;
  place-items: center;
  padding: 4px 8px;
  color: #333544;
  font-size: clamp(24px, 7vw, 34px);
  font-weight: 750;
  line-height: 1.2;
  text-align: center;
  overflow-wrap: anywhere;
}

.operators {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: clamp(12px, 4vw, 20px);
  margin-top: clamp(8px, 2dvh, 20px);
}

.operators button {
  aspect-ratio: 1 / 1;
  border-radius: clamp(12px, 4vw, 16px);
  background: var(--cream);
  color: var(--orange);
  font-size: clamp(38px, 12vw, 56px);
  font-weight: 800;
  box-shadow: 0 8px 18px rgba(255, 91, 40, 0.08);
}

.operators button.active {
  background: #ffe0d2;
  box-shadow: inset 0 0 0 4px rgba(255, 91, 40, 0.18);
}

.bottom-actions {
  min-height: 50px;
  display: flex;
  justify-content: center;
  gap: 12px;
}

.bottom-actions button,
.heart-view button,
dialog button {
  min-width: 112px;
  min-height: 44px;
  border-radius: 10px;
  background: var(--ink);
  color: white;
  font-weight: 700;
  padding: 0 18px;
}

.bottom-actions button[hidden] {
  display: none;
}

.heart-view {
  flex: 1;
  display: grid;
  place-items: center;
  align-content: center;
  gap: 42px;
  padding-bottom: 90px;
}

.heart {
  width: min(62vw, 260px);
  aspect-ratio: 1 / 1;
  background: #ff4f74;
  transform: rotate(45deg);
  position: relative;
  border-radius: 16px;
  box-shadow: 0 22px 50px rgba(255, 79, 116, 0.28);
  animation: pulse 1.15s ease-in-out infinite;
}

.heart::before,
.heart::after {
  content: "";
  position: absolute;
  width: 100%;
  height: 100%;
  border-radius: 50%;
  background: inherit;
}

.heart::before {
  left: -50%;
}

.heart::after {
  top: -50%;
}

dialog {
  width: min(calc(100vw - 48px), 360px);
  border: 0;
  border-radius: 18px;
  padding: 24px;
  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.18);
}

dialog::backdrop {
  background: rgba(20, 22, 30, 0.28);
}

dialog h2 {
  margin: 0 0 12px;
}

dialog p {
  margin: 0 0 22px;
  font-size: 20px;
  line-height: 1.45;
}

@keyframes pulse {
  0%,
  100% {
    transform: rotate(45deg) scale(1);
  }
  50% {
    transform: rotate(45deg) scale(1.07);
  }
}

@media (max-width: 420px) {
  .app {
    padding: max(28px, env(safe-area-inset-top)) 18px max(22px, env(safe-area-inset-bottom));
  }

  .topbar {
    grid-template-columns: 36px 1fr auto;
    gap: 8px;
  }

  .actions {
    gap: 8px;
  }

  .mini-btn,
  .answer-btn {
    width: 56px;
    height: 56px;
  }

  .mini-btn small,
  .answer-btn small {
    font-size: 15px;
  }

  .tiles {
    gap: 10px;
  }

  .operators {
    gap: 12px;
  }
}

@media (max-height: 720px) {
  .topbar {
    min-height: 64px;
  }

  .game-view {
    padding-top: 18px;
    gap: 12px;
  }

  .operators {
    margin-top: 16px;
  }

  .expression {
    min-height: 34px;
    font-size: clamp(20px, 6vw, 28px);
  }

  .bottom-actions {
    min-height: 42px;
  }
}