* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

:root {
  --bg: #f0fff4;
  --primary: #38a169;
  --secondary: #f6ad55;
  --text: #2d3748;
  --card-back: #2f855a;
  --card-face: #fff;
  --radius: 14px;
}

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: var(--bg);
  font-family: 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', 'Noto Sans JP', sans-serif;
  color: var(--text);
  user-select: none;
  touch-action: manipulation;
}

.screen {
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  padding: 16px;
  position: absolute;
  inset: 0;
}
.screen.active { display: flex; }

/* ---- Title ---- */
.logo {
  font-size: clamp(2.5rem, 10vw, 4rem);
  font-weight: 900;
  text-align: center;
  line-height: 1.1;
  color: var(--primary);
  text-shadow: 3px 3px 0 rgba(56,161,105,0.18);
  margin-bottom: 24px;
}

.select-label {
  font-size: 0.85rem;
  color: #888;
  margin-bottom: 12px;
  text-align: center;
}

.difficulty-select {
  display: flex;
  flex-direction: column;
  gap: 10px;
  width: 100%;
  max-width: 300px;
  align-items: center;
}

.btn-diff {
  width: 100%;
  background: var(--card-face);
  border: 2px solid var(--primary);
  border-radius: var(--radius);
  padding: 14px 20px;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  transition: transform 0.1s, box-shadow 0.1s;
  box-shadow: 0 3px 10px rgba(0,0,0,0.07);
  min-height: 72px;
}
.btn-diff:active { transform: scale(0.97); }

.diff-name {
  font-size: 1.1rem;
  font-weight: 800;
  color: var(--primary);
}
.diff-info {
  font-size: 0.78rem;
  color: #888;
}
.diff-hs {
  font-size: 0.72rem;
  color: var(--secondary);
  font-weight: 700;
}

.label {
  font-size: 0.62rem;
  color: #aaa;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  display: block;
  text-align: center;
}

/* ---- Game screen ---- */
#screen-game {
  justify-content: flex-start;
  padding: 0;
}

.game-header {
  display: flex;
  align-items: center;
  justify-content: space-around;
  width: 100%;
  max-width: 420px;
  padding: 10px 16px;
  background: #fff;
  box-shadow: 0 2px 8px rgba(0,0,0,0.07);
  flex-shrink: 0;
}

.stat-box {
  display: flex;
  flex-direction: column;
  align-items: center;
}
.stat-box span:last-child, .stat-box > span:not(.label) {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--text);
}

/* ---- Card Grid ---- */
.card-grid {
  flex: 1;
  display: grid;
  gap: clamp(6px, 1.5vw, 10px);
  padding: clamp(10px, 2.5vw, 20px);
  width: 100%;
  max-width: 420px;
  align-content: center;
  perspective: 1000px;
}

/* ---- Card ---- */
.card {
  aspect-ratio: 1;
  cursor: pointer;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.35s ease;
  min-width: 44px;
  min-height: 44px;
}

.card.flipped {
  transform: rotateY(180deg);
}

.card.matched {
  transform: rotateY(180deg);
  pointer-events: none;
}

.card-face, .card-back {
  position: absolute;
  inset: 0;
  border-radius: 10px;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: clamp(1.4rem, 4vw, 2.2rem);
  box-shadow: 0 3px 10px rgba(0,0,0,0.12);
}

.card-back {
  background: var(--card-back);
  color: rgba(255,255,255,0.6);
  font-size: clamp(1.2rem, 3.5vw, 2rem);
}

.card-face {
  background: var(--card-face);
  transform: rotateY(180deg);
}

.card.matched .card-face {
  background: #e6ffed;
  box-shadow: 0 3px 10px rgba(56,161,105,0.3);
}

/* matched pop */
@keyframes matchPop {
  0%   { transform: rotateY(180deg) scale(1); }
  50%  { transform: rotateY(180deg) scale(1.08); }
  100% { transform: rotateY(180deg) scale(1); }
}
.card.pop { animation: matchPop 0.25s ease-out forwards; }

/* mismatch shake */
@keyframes shake {
  0%, 100% { transform: rotateY(180deg) translateX(0); }
  20%       { transform: rotateY(180deg) translateX(-5px); }
  60%       { transform: rotateY(180deg) translateX(5px); }
}
.card.shake { animation: shake 0.3s ease-in-out forwards; }

/* ---- Buttons ---- */
.btn-primary {
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 50px;
  padding: 16px 48px;
  font-size: 1.2rem;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 5px 16px rgba(56,161,105,0.35);
  transition: transform 0.1s;
  min-height: 52px;
}
.btn-primary:active { transform: scale(0.96); }

.btn-secondary {
  background: transparent;
  color: var(--primary);
  border: 2px solid var(--primary);
  border-radius: 50px;
  padding: 12px 32px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  margin-top: 10px;
  min-height: 48px;
}

/* ---- Clear ---- */
.stars {
  font-size: 2.5rem;
  margin-bottom: 8px;
  letter-spacing: 4px;
}
.clear-title {
  font-size: 2rem;
  font-weight: 900;
  color: var(--primary);
  margin-bottom: 20px;
}
.result-card {
  background: #fff;
  border-radius: var(--radius);
  padding: 20px 36px;
  width: 100%;
  max-width: 300px;
  margin-bottom: 24px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.08);
}
.result-row {
  display: flex;
  justify-content: space-between;
  padding: 8px 0;
  border-bottom: 1px solid #f0f0f0;
  font-size: 1rem;
}
.result-row:last-child { border-bottom: none; }
.result-row span:last-child { font-weight: 800; }
.result-hs { color: var(--secondary); font-weight: 700; }