html, body {
  width: 100%;
  overscroll-behavior: none;
  overscroll-behavior-y: none;
  margin: 0;
  padding: 0;
  height: 100%;
  overflow: hidden;
  font-family: var(--font-body);
  background: radial-gradient(1200px 800px at 50% 18%, rgba(255,255,255,0.26), rgba(0,0,0,0.12)),
              linear-gradient(180deg, #a9ddff 0%, #79b9ff 45%, #9ee6b5 100%);
  user-select: none;
  -webkit-user-select: none;
  -ms-user-select: none;
  -webkit-touch-callout: none;
}

:root {
  --font-body: "Rubik", "Trebuchet MS", system-ui, -apple-system, Segoe UI, Arial, sans-serif;
  --font-title: "Russo One", "Rubik", "Trebuchet MS", system-ui, sans-serif;
  /* Stable (non-resizing) per-level background. Updated from JS. */
  --bgUrl: url('assets/bg_clouds.jpg');
  --bgSizeW: 100vw;
  --bgSizeH: 100vh;
  --uiStroke: rgba(255,255,255,0.70);
  --uiShadow: 0 12px 26px rgba(0,0,0,0.24);
  --btnA: #ffb35b;
  --btnB: #ff7b5b;
  --btnC: #7bd8ff;
  --btnD: #2fa7ff;
  --accent: #ffd66a;
  --accent2: #53e6c0;
  --panelBg: rgba(16, 24, 34, 0.74);
  --glass: rgba(255,255,255,0.16);
  --hudBg: rgba(8, 14, 20, 0.58);
  --hudBorder: rgba(255,255,255,0.20);
}

/* Background layer sits behind canvases and UI.
   Important: we keep its size stable (fixed px set via CSS vars) so resizing the browser doesn't
   distort or occasionally "drop" the in-canvas background. */
#bg-layer {
  position: fixed;
  inset: 0;
  z-index: -5;
  pointer-events: none;
  background-image: var(--bgUrl);
  background-repeat: no-repeat;
  background-position: center;
  background-size: var(--bgSizeW) var(--bgSizeH);
  /* Slight overscan so blur doesn't reveal edges */
  transform: scale(1.06);
  filter: blur(3px);
  will-change: transform;
}

#bg-layer::after {
  content: '';
  position: absolute;
  inset: 0;
  /* Soft vignette overlay */
  background: radial-gradient(1200px 800px at 50% 18%, rgba(255,255,255,0.10), rgba(0,0,0,0.22));
}

#game {
  width: 100vw;
  height: 100vh;
  display: block;
  touch-action: none;
}

body.booting > :not(#boot-overlay) {
  visibility: hidden;
}

.boot-overlay {
  position: fixed;
  inset: 0;
  z-index: 20;
  display: grid;
  place-items: center;
  background: #0c1118;
  pointer-events: all;
  opacity: 1;
  transition: opacity 0.2s ease;
}

.boot-overlay.hidden {
  opacity: 0;
  pointer-events: none;
}

.boot-spinner {
  width: 64px;
  height: 64px;
  border-radius: 50%;
  border: 6px solid rgba(255,255,255,0.18);
  border-top-color: rgba(255,255,255,0.92);
  animation: spin 0.9s linear infinite;
}

@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

#ui-top {
  position: fixed;
  top: calc(14px + env(safe-area-inset-top, 0px));
  left: 14px;
  right: 14px;
  display: flex;
  align-items: center;
  gap: 10px;
  pointer-events: none;
  z-index: 2;
  animation: ui-fade 0.35s ease;
}

#ui-tools {
  margin-left: auto;
  display: flex;
  gap: 8px;
  pointer-events: auto;
}

.ui-btn {
  pointer-events: auto;
  border: 0;
  border-radius: 18px;
  padding: 11px 13px;
  font-size: 18px;
  font-family: var(--font-title);
  font-weight: 700;
  background: linear-gradient(180deg, var(--btnA) 0%, var(--btnB) 100%);
  box-shadow: var(--uiShadow), inset 0 2px 0 rgba(255,255,255,0.28);
  color: #fff;
  outline: 3px solid rgba(255,255,255,0.0);
  transition: transform 0.12s ease, filter 0.18s ease;
}

.ui-btn:focus-visible {
  outline: 3px solid var(--uiStroke);
}

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

.ui-btn.active {
  filter: saturate(1.2) brightness(1.08);
  box-shadow: 0 10px 24px rgba(0,0,0,0.28), inset 0 2px 0 rgba(255,255,255,0.35);
}

.ui-btn-small {
  padding: 8px 10px;
  font-size: 16px;
  border-radius: 12px;
}

.tool-btn {
  position: relative;
  padding: 9px 12px;
  min-width: 44px;
  background: linear-gradient(180deg, var(--btnC) 0%, var(--btnD) 100%);
}

.tool-btn .tool-icon {
  font-size: 18px;
  line-height: 1;
}

.tool-btn.rotate-btn {
  background: linear-gradient(180deg, #f0c38a 0%, #b36d39 100%);
  border: 1px solid rgba(255,255,255,0.28);
  box-shadow: var(--uiShadow), inset 0 2px 0 rgba(255,255,255,0.28);
}

.tool-btn.rotate-btn::before {
  content: '';
  position: absolute;
  inset: 6px;
  background: url('assets/arrow.png') center / 70% no-repeat;
  opacity: 0.9;
  pointer-events: none;
  filter: drop-shadow(0 2px 3px rgba(0,0,0,0.35));
}

.tool-btn.rotate-btn .tool-icon {
  opacity: 0;
}

.tool-btn .tool-price {
  position: absolute;
  top: -6px;
  right: -6px;
  font-size: 11px;
  font-weight: 700;
  padding: 2px 6px;
  border-radius: 10px;
  color: #fff;
  background: rgba(0,0,0,0.52);
  border: 1px solid rgba(255,255,255,0.35);
  box-shadow: 0 6px 14px rgba(0,0,0,0.25);
}

.tool-btn:disabled {
  opacity: 0.55;
  filter: grayscale(0.2);
}

#coins {
  pointer-events: auto;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  border-radius: 16px;
  background: var(--glass);
  color: #f7f7f7;
  box-shadow: var(--uiShadow);
  border: 1px solid rgba(255,255,255,0.28);
  backdrop-filter: blur(6px);
}

#coin-count {
  font-weight: 800;
  font-size: 18px;
  min-width: 30px;
  text-align: right;
  font-family: var(--font-title);
}

#level-title {
  position: fixed;
  top: 86px;
  left: 50%;
  transform: translateX(-50%);
  font-family: var(--font-title);
  font-weight: 800;
  letter-spacing: 1px;
  font-size: 34px;
  color: #fff;
  text-shadow: 0 6px 18px rgba(0,0,0,0.22);
  padding: 10px 16px;
  border-radius: 999px;
  background: rgba(8, 12, 18, 0.28);
  border: 2px solid rgba(255,255,255,0.32);
  pointer-events: none;
  user-select: none;
  z-index: 2;
  animation: ui-fade 0.4s ease;
}

.overlay {
  position: fixed;
  inset: 0;
  display: grid;
  place-items: center;
  background: rgba(0,0,0,0.45);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  z-index: 5;
  opacity: 1;
  transition: opacity 0.18s ease;
}

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

.panel {
  width: min(740px, calc(100vw - 32px));
  max-height: min(720px, calc(100vh - 32px));
  overflow: auto;
  border-radius: 22px;
  background: linear-gradient(160deg, rgba(22, 32, 44, 0.92), rgba(10, 14, 22, 0.78));
  color: #fff;
  box-shadow: 0 18px 44px rgba(0,0,0,0.45);
  padding: 18px;
  border: 2px solid rgba(255,255,255,0.22);
  backdrop-filter: blur(7px);
  transition: transform 0.18s ease, opacity 0.18s ease;
}

.overlay.hidden .panel {
  transform: translateY(8px) scale(0.98);
  opacity: 0.96;
}

.overlay:not(.hidden) .panel {
  animation: panel-pop 0.28s ease;
}

.panel-title {
  font-size: 26px;
  font-weight: 800;
  font-family: var(--font-title);
  padding: 8px 6px 10px;
}

.panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.levels {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 10px;
  padding: 10px 0 14px;
}

.level-btn {
  position: relative;
  border: 0;
  border-radius: 14px;
  padding: 14px 0 22px;
  font-weight: 800;
  font-size: 16px;
  color: #fff;
  background: linear-gradient(180deg, rgba(255,255,255,0.22), rgba(255,255,255,0.06));
  box-shadow: inset 0 2px 0 rgba(255,255,255,0.14);
  transition: transform 0.12s ease, filter 0.18s ease;
}

.level-btn.unlocked { background: rgba(255,255,255,0.18); }
.level-btn.locked   { opacity: 0.35; }

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

.level-stars {
  position: absolute;
  left: 50%;
  bottom: 5px;
  transform: translateX(-50%);
  font-size: 12px;
  letter-spacing: 1px;
  color: var(--accent);
  opacity: 0.9;
  pointer-events: none;
}

.panel-footer {
  display: flex;
  gap: 12px;
  justify-content: center;
  padding: 8px 0 6px;
}

.big-btn {
  border: 0;
  border-radius: 16px;
  padding: 12px 18px;
  font-weight: 800;
  font-size: 18px;
  font-family: var(--font-title);
  color: #fff;
  background: linear-gradient(180deg, #7cff9a 0%, #21b24b 100%);
  box-shadow: 0 12px 24px rgba(0,0,0,0.28), inset 0 2px 0 rgba(255,255,255,0.2);
  transition: transform 0.12s ease, filter 0.18s ease;
}

.big-btn.secondary {
  background: linear-gradient(180deg, rgba(255,255,255,0.18) 0%, rgba(255,255,255,0.12) 100%);
}

/* HUD */
#hud {
  position: fixed;
  left: 50%;
  bottom: calc(14px + env(safe-area-inset-bottom, 0px));
  transform: translateX(-50%);
  width: min(520px, calc(100vw - 24px));
  padding: 10px 14px 12px;
  border-radius: 18px;
  background: var(--hudBg);
  border: 1px solid var(--hudBorder);
  box-shadow: var(--uiShadow);
  color: #fff;
  display: grid;
  gap: 8px;
  backdrop-filter: blur(6px);
  pointer-events: none;
  z-index: 2;
  animation: ui-fade 0.45s ease;
}

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

.hud-metric {
  text-align: center;
}

.hud-label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  opacity: 0.72;
}

.hud-value {
  font-size: 18px;
  font-weight: 800;
  font-family: var(--font-title);
}

.hud-progress {
  height: 8px;
  border-radius: 999px;
  background: rgba(255,255,255,0.16);
  overflow: hidden;
}

.hud-progress-fill {
  height: 100%;
  width: 0%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent2), var(--accent));
  transition: width 0.2s ease;
}

.hud-stars {
  display: flex;
  justify-content: center;
  gap: 4px;
  font-size: 14px;
  color: var(--accent);
  text-shadow: 0 2px 8px rgba(0,0,0,0.35);
}

.toast {
  position: fixed;
  left: 50%;
  top: calc(140px + env(safe-area-inset-top, 0px));
  transform: translateX(-50%);
  padding: 10px 14px;
  border-radius: 14px;
  background: rgba(10, 16, 22, 0.78);
  border: 1px solid rgba(255,255,255,0.16);
  color: #fff;
  font-size: 14px;
  box-shadow: 0 12px 24px rgba(0,0,0,0.28);
  backdrop-filter: blur(6px);
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease;
}

.toast.hidden {
  transform: translateX(-50%) translateY(6px);
}

@keyframes ui-fade {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes panel-pop {
  0% { transform: translateY(10px) scale(0.96); opacity: 0.6; }
  100% { transform: translateY(0) scale(1); opacity: 1; }
}

/* Tutorial */
.tutorial-panel {
  width: min(560px, calc(100vw - 32px));
}

.tut-body {
  display: grid;
  gap: 12px;
  padding: 4px 6px 12px;
}

.tut-text {
  font-size: 18px;
  line-height: 1.35;
  background: rgba(255,255,255,0.12);
  border: 2px dashed rgba(255,255,255,0.30);
  border-radius: 18px;
  padding: 12px 14px;
  display: grid;
  gap: 10px;
}

.tut-cubes {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.tut-cube {
  position: relative;
  border-radius: 14px;
  padding: 10px 12px 12px;
  min-height: 86px;
  border: 1px solid rgba(255,255,255,0.55);
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.35), 0 12px 20px rgba(0,0,0,0.24);
  overflow: hidden;
}

.tut-cube::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(140deg, rgba(255,255,255,0.40), rgba(255,255,255,0.0) 55%);
  pointer-events: none;
}

.tut-cube::after {
  content: '';
  position: absolute;
  inset: 8px;
  background: url('assets/arrow.png') center / 65% no-repeat;
  opacity: 0.22;
  pointer-events: none;
}

.tut-cube-crystal {
  background: linear-gradient(145deg, rgba(92,172,255,0.95), rgba(179,223,255,0.95));
}

.tut-cube-bonus {
  background: linear-gradient(145deg, rgba(245,173,72,0.95), rgba(255,226,150,0.95));
}

.tut-cube-title {
  font-weight: 800;
  font-size: 16px;
  position: relative;
  z-index: 1;
}

.tut-cube-desc {
  font-size: 13px;
  opacity: 0.9;
  position: relative;
  z-index: 1;
}

.tut-cube-note {
  font-size: 14px;
  opacity: 0.85;
}

@media (max-width: 420px) {
  .tut-cubes {
    grid-template-columns: 1fr;
  }
}

.tut-dots {
  display: flex;
  justify-content: center;
  gap: 8px;
}

.tut-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: rgba(255,255,255,0.26);
}

.tut-dot.on {
  background: rgba(255,255,255,0.92);
}

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

.hint {
  opacity: 0.75;
  font-size: 13px;
  line-height: 1.35;
  padding: 8px 6px 2px;
}

/* Shop */
.shop-panel {
  width: min(560px, calc(100vw - 32px));
}

.shop-grid {
  display: grid;
  gap: 10px;
  padding: 6px 2px 8px;
}

.shop-item {
  border: 0;
  border-radius: 16px;
  padding: 12px 14px;
  color: #fff;
  background: rgba(255,255,255,0.12);
  box-shadow: inset 0 2px 0 rgba(255,255,255,0.14);
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 12px;
  text-align: left;
  transition: transform 0.12s ease, filter 0.18s ease;
}

.shop-item.rotate-item {
  background: linear-gradient(180deg, rgba(255, 210, 160, 0.25), rgba(160, 90, 40, 0.25));
  border: 1px solid rgba(255,255,255,0.2);
}

.shop-item:active { transform: translateY(1px); }

.shop-item:disabled {
  opacity: 0.4;
  filter: grayscale(0.3);
}

.shop-icon {
  font-size: 22px;
}

.shop-text {
  display: grid;
  gap: 4px;
}

.shop-name {
  font-weight: 800;
  font-size: 16px;
  font-family: var(--font-title);
}

.shop-desc {
  font-size: 12px;
  opacity: 0.75;
}

.shop-price {
  font-weight: 800;
  font-size: 14px;
  color: var(--accent);
}

.shop-note {
  font-size: 12px;
  opacity: 0.75;
  padding: 4px 6px 10px;
  text-align: center;
}

/* Win stats */
.win-stats {
  display: grid;
  gap: 12px;
  padding: 4px 6px 8px;
}

.win-stars {
  display: flex;
  justify-content: center;
  gap: 6px;
  font-size: 22px;
  color: var(--accent);
  text-shadow: 0 4px 10px rgba(0,0,0,0.35);
}

.win-metrics {
  display: grid;
  gap: 6px;
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.16);
  border-radius: 14px;
  padding: 10px 12px;
}

.win-metric {
  display: flex;
  justify-content: space-between;
  font-size: 14px;
}

.win-note {
  text-align: center;
  font-size: 13px;
  color: var(--accent2);
  min-height: 16px;
}

/* Settings */
.settings-panel {
  width: min(520px, calc(100vw - 32px));
}

.settings-grid {
  display: grid;
  gap: 12px;
  padding: 8px 2px 10px;
}

.settings-item {
  border: 0;
  border-radius: 16px;
  padding: 12px 14px;
  color: #fff;
  background: rgba(255,255,255,0.12);
  box-shadow: inset 0 2px 0 rgba(255,255,255,0.14);
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 12px;
  text-align: left;
  transition: transform 0.12s ease, filter 0.18s ease;
}

.settings-item.danger {
  background: linear-gradient(180deg, rgba(255, 120, 120, 0.22), rgba(255, 120, 120, 0.1));
  border: 1px solid rgba(255, 150, 150, 0.25);
}

.settings-item:active { transform: translateY(1px); }

.settings-icon {
  font-size: 22px;
}

.settings-text {
  display: grid;
  gap: 4px;
}

.settings-name {
  font-weight: 800;
  font-size: 16px;
  font-family: var(--font-title);
}

.settings-desc {
  font-size: 12px;
  opacity: 0.78;
}

.settings-toggle {
  font-size: 12px;
  font-weight: 800;
  padding: 6px 10px;
  border-radius: 999px;
  background: rgba(255,255,255,0.16);
  border: 1px solid rgba(255,255,255,0.28);
}

@media (max-width: 420px) {
  #ui-top { flex-wrap: wrap; }
  #ui-tools { margin-left: 0; }
  #coins { margin-left: auto; }
  #level-title { font-size: 28px; top: 84px; }
  .levels { grid-template-columns: repeat(4, 1fr); }
  #hud { bottom: 10px; }
  .hud-row { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .toast { top: calc(132px + env(safe-area-inset-top, 0px)); }
}

@media (max-width: 520px) {
  #ui-top {
    flex-wrap: wrap;
    gap: 8px;
    top: calc(8px + env(safe-area-inset-top, 0px));
    left: 8px;
    right: 8px;
  }

  #ui-tools {
    position: fixed;
    right: 10px;
    bottom: calc(118px + env(safe-area-inset-bottom, 0px));
    flex-direction: column;
    gap: 8px;
    margin-left: 0;
  }

  #ui-tools .tool-btn {
    min-width: 46px;
    padding: 10px 12px;
    border-radius: 16px;
  }

  #coins {
    padding: 6px 8px;
    border-radius: 14px;
    gap: 8px;
  }

  #coin-count {
    font-size: 16px;
    min-width: 24px;
  }

  #level-title {
    font-size: 22px;
    padding: 6px 10px;
    top: 72px;
    max-width: calc(100vw - 34px);
    text-align: center;
  }

  #hud {
    width: min(480px, calc(100vw - 20px));
    padding: 8px 12px 10px;
    bottom: calc(8px + env(safe-area-inset-bottom, 0px));
  }

  .hud-label { font-size: 10px; }
  .hud-value { font-size: 16px; }
  .hud-progress { height: 6px; }
  .toast { top: calc(120px + env(safe-area-inset-top, 0px)); }
}

@media (min-width: 900px) {
  .ui-btn {
    padding: 14px 18px;
    font-size: 22px;
    border-radius: 22px;
  }

  .ui-btn-small {
    padding: 10px 12px;
    font-size: 18px;
    border-radius: 14px;
  }

  .tool-btn {
    min-width: 52px;
    padding: 12px 16px;
  }

  .tool-btn .tool-icon {
    font-size: 20px;
  }

  .tool-btn .tool-price {
    font-size: 12px;
  }
}