:root {
  --bg-abyss: #070a14;
  --surface-panel: rgba(14, 21, 38, 0.88);
  --border-neon: rgba(0, 240, 255, 0.35);
  --primary-neon: #00f0ff;
  --accent-green: #00ff88;
  --danger-crimson: #ff0055;
  --warning-amber: #ffaa00;
  --text-main: #f0f6fc;
  --text-muted: #8b9bb4;
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  user-select: none;
  -webkit-user-select: none;
  touch-action: none;
}

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg-abyss);
  font-family: var(--font-family);
  color: var(--text-main);
}

#game-container {
  position: relative;
  width: 100vw;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

#slope-canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: block;
}

/* In-Game HUD */
.hud-overlay {
  position: absolute;
  top: 16px;
  left: 20px;
  right: 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  pointer-events: none;
  z-index: 10;
}

.hud-stat {
  display: flex;
  flex-direction: column;
  background: rgba(7, 10, 20, 0.65);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  padding: 8px 14px;
  border-radius: 10px;
  border: 1px solid rgba(0, 240, 255, 0.2);
}

.hud-label {
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 1.5px;
  color: var(--text-muted);
}

.hud-value {
  font-size: 20px;
  font-weight: 900;
  color: var(--primary-neon);
  font-variant-numeric: tabular-nums;
  text-shadow: 0 0 10px rgba(0, 240, 255, 0.4);
}

.center-stat {
  padding: 6px 16px;
  border-color: rgba(0, 255, 136, 0.3);
}

.hud-multiplier {
  font-size: 18px;
  font-weight: 900;
  color: var(--accent-green);
  text-shadow: 0 0 12px rgba(0, 255, 136, 0.6);
}

.hud-actions {
  pointer-events: auto;
}

.icon-btn {
  background: rgba(14, 21, 38, 0.7);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-neon);
  color: var(--text-main);
  border-radius: 10px;
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  cursor: pointer;
  transition: all 0.15s ease;
}

.icon-btn:hover {
  background: rgba(0, 240, 255, 0.2);
  border-color: var(--primary-neon);
  transform: scale(1.05);
}

/* Mobile Touch Zones */
.touch-zones {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: flex;
  pointer-events: auto;
  z-index: 5;
}

.touch-zone {
  flex: 1;
  height: 100%;
  display: flex;
  align-items: flex-end;
  padding-bottom: 24px;
  opacity: 0.15;
  transition: opacity 0.2s, background 0.2s;
}

.touch-left {
  justify-content: flex-start;
  padding-left: 20px;
}

.touch-right {
  justify-content: flex-end;
  padding-right: 20px;
}

.touch-hint {
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 1px;
  color: var(--primary-neon);
  pointer-events: none;
}

.touch-zone:active {
  opacity: 0.4;
  background: radial-gradient(circle at center, rgba(0, 240, 255, 0.15) 0%, transparent 70%);
}

/* Overlays & Modals */
.overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(4, 6, 12, 0.82);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 20;
  padding: 20px;
  transition: opacity 0.2s ease, visibility 0.2s ease;
}

.overlay.hidden {
  display: none !important;
}

.modal-card {
  background: var(--surface-panel);
  border: 1px solid var(--border-neon);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.7), 0 0 30px rgba(0, 240, 255, 0.15);
  border-radius: 20px;
  padding: 32px 28px;
  max-width: 420px;
  width: 100%;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.modal-badge {
  font-size: 11px;
  font-weight: 900;
  letter-spacing: 2px;
  color: var(--accent-green);
  background: rgba(0, 255, 136, 0.12);
  border: 1px solid rgba(0, 255, 136, 0.3);
  padding: 4px 12px;
  border-radius: 20px;
}

.modal-badge.alert {
  color: var(--danger-crimson);
  background: rgba(255, 0, 85, 0.12);
  border-color: rgba(255, 0, 85, 0.3);
}

.modal-title {
  font-size: 28px;
  font-weight: 900;
  letter-spacing: 1px;
  color: #fff;
  text-shadow: 0 0 16px rgba(0, 240, 255, 0.5);
}

.modal-desc {
  font-size: 14px;
  line-height: 1.5;
  color: var(--text-muted);
}

.controls-guide {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 8px;
  background: rgba(7, 10, 20, 0.5);
  padding: 12px 16px;
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.guide-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
}

.key-pill {
  background: rgba(0, 240, 255, 0.15);
  border: 1px solid rgba(0, 240, 255, 0.4);
  color: var(--primary-neon);
  font-weight: 800;
  font-size: 11px;
  padding: 2px 7px;
  border-radius: 6px;
}

.guide-text {
  color: var(--text-muted);
  margin-left: auto;
}

.results-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  width: 100%;
}

.res-card {
  background: rgba(7, 10, 20, 0.6);
  border: 1px solid rgba(0, 240, 255, 0.15);
  border-radius: 12px;
  padding: 10px 6px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.res-label {
  font-size: 9px;
  font-weight: 800;
  letter-spacing: 1px;
  color: var(--text-muted);
}

.res-value {
  font-size: 15px;
  font-weight: 900;
  color: var(--primary-neon);
  font-variant-numeric: tabular-nums;
}

.btn-primary {
  width: 100%;
  padding: 14px 20px;
  font-size: 16px;
  font-weight: 900;
  letter-spacing: 1.5px;
  color: #070a14;
  background: linear-gradient(135deg, #00f0ff 0%, #00ff88 100%);
  border: none;
  border-radius: 12px;
  cursor: pointer;
  box-shadow: 0 8px 24px rgba(0, 240, 255, 0.35);
  transition: all 0.15s ease;
  margin-top: 6px;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 30px rgba(0, 240, 255, 0.5);
}

.btn-primary:active {
  transform: translateY(1px);
}