* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
  -webkit-user-select: none;
}

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: #0a0a1a;
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  touch-action: none;
}

#gameCanvas {
  display: block;
  width: 100%;
  height: 100%;
  image-rendering: pixelated;
}

/* ── Start Screen ────────────────────────────────────────────── */

#startScreen {
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  transition: opacity 0.6s ease-out;
  overflow: hidden;
}

#startScreen.hidden {
  opacity: 0;
  pointer-events: none;
}

.title-bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse at 30% 20%, rgba(102,126,234,0.6) 0%, transparent 60%),
    radial-gradient(ellipse at 70% 80%, rgba(118,75,162,0.5) 0%, transparent 60%),
    radial-gradient(ellipse at 50% 50%, rgba(255,107,107,0.15) 0%, transparent 70%),
    linear-gradient(160deg, #1a0a2e 0%, #16213e 40%, #0f3460 100%);
  animation: bgPulse 6s ease-in-out infinite alternate;
}

@keyframes bgPulse {
  0% { filter: brightness(1) hue-rotate(0deg); }
  100% { filter: brightness(1.15) hue-rotate(10deg); }
}

.title-content {
  position: relative;
  z-index: 2;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 0 1.5em;
}

.title-badge {
  font-size: clamp(0.55rem, 1.8vw, 0.75rem);
  color: rgba(255,255,255,0.45);
  letter-spacing: 0.4em;
  text-transform: uppercase;
  margin-bottom: 0.8em;
}

#startScreen h1 {
  font-size: clamp(2.4rem, 9vw, 5.5rem);
  color: #fff;
  text-shadow:
    0 0 30px rgba(102,126,234,0.6),
    0 4px 0 rgba(0,0,0,0.3),
    0 0 60px rgba(118,75,162,0.3);
  margin-bottom: 0.15em;
  line-height: 1.05;
  font-weight: 900;
  letter-spacing: -0.02em;
}

.title-accent {
  background: linear-gradient(90deg, #ff6b6b, #ffd700, #ff6b6b);
  background-size: 200% 100%;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: shimmer 3s ease-in-out infinite;
}

@keyframes shimmer {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

#startScreen .subtitle {
  font-size: clamp(0.85rem, 2.8vw, 1.3rem);
  color: rgba(255,255,255,0.7);
  margin-bottom: 1.8em;
  font-weight: 300;
}

#startBtn {
  font-size: clamp(1.1rem, 3.5vw, 1.6rem);
  padding: 0.75em 2.8em;
  border: none;
  border-radius: 50px;
  background: linear-gradient(135deg, #ff6b6b, #ee5a24);
  color: #fff;
  font-weight: 800;
  cursor: pointer;
  box-shadow:
    0 4px 20px rgba(255,107,107,0.4),
    0 0 40px rgba(255,107,107,0.15),
    inset 0 1px 0 rgba(255,255,255,0.2);
  transition: transform 0.15s, box-shadow 0.15s;
  letter-spacing: 0.08em;
  display: flex;
  align-items: center;
  gap: 0.5em;
}

#startBtn:hover {
  transform: scale(1.06) translateY(-2px);
  box-shadow:
    0 8px 30px rgba(255,107,107,0.5),
    0 0 60px rgba(255,107,107,0.2),
    inset 0 1px 0 rgba(255,255,255,0.2);
}

#startBtn:active {
  transform: scale(0.97);
}

.btn-icon {
  font-size: 0.8em;
}

.instructions {
  margin-top: 2em;
  display: flex;
  flex-direction: column;
  gap: 0.4em;
}

.ctrl-hint {
  color: rgba(255,255,255,0.45);
  font-size: clamp(0.7rem, 2.2vw, 0.9rem);
  line-height: 1.4;
}

.hi-score {
  margin-top: 1.5em;
  color: #ffd700;
  font-size: clamp(0.8rem, 2.5vw, 1rem);
  font-weight: 700;
  opacity: 0.8;
}

/* ── HUD ─────────────────────────────────────────────────────── */

#hud {
  position: fixed;
  top: 0; left: 0; right: 0;
  display: none;
  justify-content: space-between;
  align-items: center;
  padding: 8px 14px;
  background: linear-gradient(180deg, rgba(0,0,0,0.6) 0%, rgba(0,0,0,0.2) 80%, transparent 100%);
  z-index: 50;
  font-size: clamp(0.85rem, 2.8vw, 1.15rem);
  color: #fff;
  font-weight: 700;
  gap: 8px;
}

#hud.active {
  display: flex;
}

.hud-left, .hud-center, .hud-right {
  display: flex;
  align-items: center;
  gap: 10px;
}

.hud-center {
  flex-direction: column;
  gap: 2px;
}

.hud-item {
  display: flex;
  align-items: center;
  gap: 4px;
}

.hud-icon {
  font-size: 1.1em;
}

#hud .coins { color: #ffd700; }
#hud .distance { color: #a8e6cf; font-size: 0.9em; }
#hud .lives { color: #ff6b6b; letter-spacing: 2px; }
#hud .combo { color: #ff9f43; font-size: 0.85em; }

.speed-bar {
  width: clamp(60px, 15vw, 100px);
  height: 4px;
  background: rgba(255,255,255,0.15);
  border-radius: 2px;
  overflow: hidden;
}

.speed-fill {
  height: 100%;
  width: 40%;
  background: linear-gradient(90deg, #a8e6cf, #ff6b6b);
  border-radius: 2px;
  transition: width 0.3s;
}

/* ── Mobile Controls ─────────────────────────────────────────── */

#mobileControls {
  position: fixed;
  bottom: 0; left: 0; right: 0;
  display: none;
  justify-content: space-between;
  align-items: flex-end;
  padding: 12px 16px 28px;
  z-index: 50;
  pointer-events: none;
}

#mobileControls.active {
  display: flex;
}

.ctrl-btn {
  width: clamp(64px, 16vw, 88px);
  height: clamp(64px, 16vw, 88px);
  border-radius: 18px;
  border: 2px solid rgba(255,255,255,0.35);
  background: rgba(0,0,0,0.35);
  backdrop-filter: blur(6px);
  color: #fff;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  pointer-events: auto;
  cursor: pointer;
  transition: background 0.1s, transform 0.1s, border-color 0.1s;
  gap: 2px;
}

.ctrl-label {
  font-size: clamp(0.5rem, 1.5vw, 0.65rem);
  font-weight: 700;
  letter-spacing: 0.1em;
  opacity: 0.7;
}

.ctrl-arrow {
  font-size: clamp(1.4rem, 4vw, 1.9rem);
}

.ctrl-btn:active, .ctrl-btn.pressed {
  background: rgba(255,255,255,0.25);
  border-color: #fff;
  transform: scale(0.93);
}

.ctrl-jump:active, .ctrl-jump.pressed {
  border-color: #a8e6cf;
  box-shadow: 0 0 20px rgba(168,230,207,0.3);
}

.ctrl-duck:active, .ctrl-duck.pressed {
  border-color: #74b9ff;
  box-shadow: 0 0 20px rgba(116,185,255,0.3);
}

.ctrl-left {
  display: flex;
  gap: 10px;
}

/* ── Game Over ───────────────────────────────────────────────── */

#gameOver {
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  display: none;
  align-items: center;
  justify-content: center;
  background: rgba(0,0,0,0.8);
  backdrop-filter: blur(8px);
  z-index: 100;
  color: #fff;
}

#gameOver.active {
  display: flex;
}

.go-panel {
  text-align: center;
  padding: 2em;
  max-width: 400px;
  width: 90%;
}

#gameOver h2 {
  font-size: clamp(2.2rem, 8vw, 4rem);
  margin-bottom: 0.4em;
  background: linear-gradient(180deg, #ff6b6b, #c0392b);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  font-weight: 900;
}

.go-stats {
  display: flex;
  justify-content: center;
  gap: clamp(1em, 4vw, 2em);
  margin-bottom: 1em;
}

.go-stat {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.go-stat-label {
  font-size: clamp(0.65rem, 2vw, 0.8rem);
  color: rgba(255,255,255,0.5);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.go-stat-val {
  font-size: clamp(1.2rem, 4vw, 1.8rem);
  font-weight: 800;
  color: #ffd700;
}

.go-rank {
  font-size: clamp(0.9rem, 3vw, 1.2rem);
  color: #a8e6cf;
  margin-bottom: 1.5em;
  min-height: 1.5em;
}

#restartBtn {
  font-size: clamp(1rem, 3.2vw, 1.4rem);
  padding: 0.7em 2.5em;
  border: none;
  border-radius: 50px;
  background: linear-gradient(135deg, #ff6b6b, #ee5a24);
  color: #fff;
  font-weight: 800;
  cursor: pointer;
  box-shadow: 0 4px 20px rgba(255,107,107,0.4);
  transition: transform 0.15s;
  letter-spacing: 0.05em;
}

#restartBtn:hover {
  transform: scale(1.05);
}

#restartBtn:active {
  transform: scale(0.97);
}