* {
  box-sizing: border-box;
}

:root {
  /* Cute cartoon mallet — hand-drawn rubber mallet (rounded pink head with
     a little face, tan handle) rather than the plain 🔨 emoji. Shared by
     the board cursor and the tap-hit swing animation below. */
  --mallet-svg: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='100' height='100'><rect x='41' y='42' width='18' height='52' rx='9' fill='%23d9a066' stroke='%238a5a25' stroke-width='3'/><rect x='16' y='6' width='68' height='42' rx='21' fill='%23ff8a80' stroke='%23c0392b' stroke-width='4'/><ellipse cx='33' cy='19' rx='12' ry='7' fill='white' opacity='0.45'/><circle cx='39' cy='24' r='3.5' fill='%232b2b2b'/><circle cx='58' cy='24' r='3.5' fill='%232b2b2b'/><path d='M 36 33 Q 48 41 61 33' stroke='%232b2b2b' stroke-width='3' fill='none' stroke-linecap='round'/></svg>");
  /* Hotspot sits where the head meets the handle so the "hit point" lines
     up with where the student is tapping. */
  --hammer-cursor: var(--mallet-svg) 20 46, pointer;
}

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  overflow-x: hidden;
  /* Disables pinch-zoom and double-tap-zoom (both fall under "zoom" and are
     excluded by omitting pinch-zoom from the allowed gesture set) while
     still allowing normal scrolling — students kept accidentally
     double-tap-zooming mid-game. viewport's user-scalable=no alone doesn't
     stop this since iOS Safari has ignored that flag since iOS 10. */
  touch-action: pan-x pan-y;
}

body {
  font-family: "PingFang TC", "Microsoft JhengHei", "Noto Sans TC", sans-serif;
  background: linear-gradient(180deg, #eaf6ff 0%, #dff0e0 100%);
  color: #2b2b2b;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

#app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 24px 16px 48px;
}

.screen {
  display: none;
  width: 100%;
  max-width: 900px;
  flex-direction: column;
  align-items: center;
  text-align: center;
  animation: fade-in 0.25s ease;
}

.screen.active {
  display: flex;
}

@keyframes fade-in {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.title {
  font-size: clamp(28px, 6vw, 44px);
  margin: 8px 0 4px;
}

.subtitle {
  font-size: clamp(18px, 3vw, 22px);
  color: #555;
  margin-bottom: 20px;
}

/* Boot / preload loading screen */
.boot-loading {
  position: relative;
  width: min(78vw, 420px);
  height: min(78vw, 420px);
  margin: 24px auto;
}

.boot-ring {
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
}

.boot-ring-bg {
  fill: none;
  stroke: #eee;
  stroke-width: 14;
}

.boot-ring-fill {
  fill: none;
  stroke: #ff9f43;
  stroke-width: 14;
  stroke-linecap: round;
  stroke-dasharray: 565.48;
  stroke-dashoffset: 565.48;
  transition: stroke-dashoffset 0.25s linear;
}

.boot-ring-center {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: clamp(28px, 7vw, 44px);
  font-weight: bold;
  color: #333;
}

.boot-note-icons {
  position: absolute;
  inset: 0;
}

.boot-note-icon {
  position: absolute;
  width: 15%;
  height: 15%;
  min-width: 44px;
  min-height: 44px;
  border-radius: 50%;
  background: white;
  object-fit: cover;
  filter: grayscale(100%);
  opacity: 0.35;
  box-shadow: 0 2px 6px rgba(0,0,0,0.08);
  transform: translate(-50%, -50%) scale(0.85);
  transition: filter 0.4s ease, opacity 0.4s ease, transform 0.3s ease;
}

.boot-note-icon.ready {
  filter: grayscale(0%);
  opacity: 1;
  transform: translate(-50%, -50%) scale(1.15);
}

.screen-title {
  font-size: clamp(26px, 5vw, 36px);
  margin: 8px 0 20px;
}

/* Buttons */
.primary-btn {
  font-size: clamp(20px, 3.5vw, 26px);
  font-weight: bold;
  padding: 18px 48px;
  margin-top: 28px;
  border: none;
  border-radius: 20px;
  background: #ff9f43;
  color: white;
  box-shadow: 0 6px 0 #d97e1a;
  cursor: pointer;
  transition: transform 0.05s ease;
}

.primary-btn:active {
  transform: translateY(4px);
  box-shadow: 0 2px 0 #d97e1a;
}

.primary-btn:disabled {
  background: #cfcfcf;
  box-shadow: 0 6px 0 #a8a8a8;
  cursor: not-allowed;
}

/* Secondary action (teacher panel's "進入遊戲" link) — same shape as
   .primary-btn but a calmer color so it doesn't compete with 開始/結束. */
.secondary-btn {
  /* Block (not inline-block) so it always starts on its own line. The
     hidden error <p> between #end-btn and this link collapses to zero
     size (display:none), so with inline-block the two buttons could end
     up side by side in the same inline flow instead of stacked. width:
     max-content + auto margins keeps it sized to its content and centered,
     matching how .primary-btn looks despite the different display type. */
  display: block;
  width: max-content;
  margin: 16px auto 0;
  font-size: clamp(18px, 3vw, 22px);
  font-weight: bold;
  padding: 14px 36px;
  border: none;
  border-radius: 20px;
  background: #4a90d9;
  color: white;
  box-shadow: 0 6px 0 #2f6cb0;
  cursor: pointer;
  text-decoration: none;
  transition: transform 0.05s ease;
}

/* 結束/進入遊戲 on the teacher panel's admin-active screen otherwise end up
   visibly different sizes — .primary-btn/.secondary-btn have different
   font-size and padding globally (used elsewhere with different text
   lengths), so pin both to the same fixed size here without touching those
   shared classes for their other uses. */
#admin-active .primary-btn,
#admin-active .secondary-btn {
  display: block;
  width: 220px;
  margin: 16px auto 0;
  font-size: 22px;
  padding: 16px 0;
  text-align: center;
}

#admin-active .primary-btn {
  margin-top: 28px;
}

.secondary-btn:active {
  transform: translateY(4px);
  box-shadow: 0 2px 0 #2f6cb0;
}

.hidden {
  display: none !important;
}

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
  z-index: 100;
  animation: overlay-fade-in 0.2s ease;
}

.modal-overlay.hidden {
  display: none;
}

.modal-box {
  background: white;
  border-radius: 20px;
  padding: 28px 24px;
  width: 100%;
  max-width: 360px;
  text-align: center;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
}

.modal-actions {
  display: flex;
  justify-content: center;
  gap: 14px;
  flex-wrap: wrap;
}

.modal-actions .primary-btn,
.modal-actions .secondary-btn {
  margin-top: 12px;
  min-width: 140px;
  font-size: clamp(18px, 3vw, 22px);
  padding: 14px 24px;
}

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

.text-input {
  display: block;
  width: 100%;
  max-width: 320px;
  font-size: clamp(18px, 3vw, 22px);
  padding: 14px 18px;
  margin: 10px auto;
  border: none;
  border-radius: 14px;
  box-shadow: inset 0 2px 6px rgba(0,0,0,0.1);
  text-align: center;
}

.error-text {
  color: #ff6b6b;
  font-weight: bold;
}

/* Section heading above each option group (teacher panel) — 音域選擇 above
   the clef-mode radios, 顯示唱名 above the show-labels checkbox. */
.option-group-label {
  max-width: 320px;
  margin: 16px auto 4px;
  text-align: left;
  font-weight: bold;
  font-size: clamp(14px, 2.5vw, 17px);
  color: #555;
}

/* Clef mode selector (teacher panel) */
.clef-mode-group {
  display: flex;
  flex-direction: column;
  gap: 10px;
  max-width: 320px;
  margin: 16px auto;
  text-align: left;
}

.clef-mode-option {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: clamp(16px, 3vw, 20px);
  background: white;
  border-radius: 12px;
  padding: 10px 16px;
  box-shadow: 0 3px 8px rgba(0,0,0,0.08);
}

.clef-mode-option input {
  width: 20px;
  height: 20px;
}

/* Show-labels toggle (teacher panel) — same card look as the clef-mode
   options above, just a single standalone checkbox instead of a group. */
.show-labels-option {
  display: flex;
  align-items: center;
  gap: 10px;
  max-width: 320px;
  margin: 16px auto;
  text-align: left;
  font-size: clamp(16px, 3vw, 20px);
  background: white;
  border-radius: 12px;
  padding: 10px 16px;
  box-shadow: 0 3px 8px rgba(0,0,0,0.08);
}

.show-labels-option input {
  width: 20px;
  height: 20px;
}

/* Login numpad */
.seat-display {
  font-size: clamp(36px, 8vw, 56px);
  letter-spacing: 8px;
  font-weight: bold;
  background: white;
  border-radius: 16px;
  padding: 12px 32px;
  margin-bottom: 24px;
  min-width: 200px;
  box-shadow: inset 0 2px 6px rgba(0,0,0,0.1);
}

/* #screen-seat-joined: extra breathing room above the "座號" label + a
   somewhat bigger number than the login screen's live-typing display,
   since here it's the main focal point of an otherwise empty screen. */
.seat-joined-label {
  margin-top: 48px;
  font-size: clamp(18px, 3.5vw, 24px);
  color: #555;
}

.seat-joined-number {
  font-size: clamp(44px, 10vw, 68px);
}

.numpad {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  width: 100%;
  max-width: 340px;
}

.num-btn {
  font-size: clamp(24px, 5vw, 32px);
  font-weight: bold;
  padding: 22px 0;
  border: none;
  border-radius: 16px;
  background: white;
  box-shadow: 0 5px 0 #c9c9c9;
  cursor: pointer;
}

.num-btn:active {
  transform: translateY(4px);
  box-shadow: 0 1px 0 #c9c9c9;
}

.num-btn.wide {
  grid-column: span 2;
  font-size: clamp(16px, 3vw, 20px);
  background: #ffe0e0;
}

/* Teacher panel: 座號 roster (collecting-seats phase) */
.roster-list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
  max-width: 480px;
  margin: 16px auto;
}

.roster-tile {
  min-width: 48px;
  padding: 10px 14px;
  font-size: clamp(16px, 3vw, 20px);
  font-weight: bold;
  border: none;
  border-radius: 12px;
  background: white;
  box-shadow: 0 4px 0 #c9c9c9;
  cursor: pointer;
}

.roster-tile:active {
  transform: translateY(3px);
  box-shadow: 0 1px 0 #c9c9c9;
}

.roster-tile:hover {
  background: #ffe0e0;
}

/* Rules */
.rules-list {
  list-style: none;
  padding: 0;
  font-size: clamp(18px, 3.5vw, 24px);
  text-align: left;
  max-width: 480px;
}

.rules-list li {
  background: white;
  border-radius: 14px;
  padding: 16px 20px;
  margin-bottom: 14px;
  box-shadow: 0 3px 8px rgba(0,0,0,0.08);
}

/* Game screen header */
.quiz-header {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: clamp(16px, 3vw, 22px);
  font-weight: bold;
  margin-bottom: 8px;
}

.timer {
  background: #ff6b6b;
  color: white;
  padding: 8px 18px;
  border-radius: 12px;
  font-variant-numeric: tabular-nums;
}

.question-counter {
  font-size: clamp(16px, 3vw, 20px);
  color: #666;
  margin: 4px 0 16px;
}

.hint {
  color: #777;
  font-size: 15px;
  margin-top: 8px;
  max-width: 320px;
}

/* Multi-line explanatory hints read poorly center-aligned (ragged line
   starts) — left-align just these while leaving the short one-line error
   hints (.error-text) centered under their form as before. */
.hint-left {
  text-align: left;
}

/* Same visual weight as Peter and the Wolf's .play-btn (font-size, padding,
   border-radius, box-shadow depth, disabled colors) — the two buttons play
   the same conceptual role (聽題目音檔), so they should look the same size
   across lessons even though this one also has extra 播放中/再聽一次 state
   handling that .play-btn doesn't need. */
.replay-btn {
  font-size: clamp(20px, 4vw, 28px);
  font-weight: bold;
  padding: 24px 40px;
  margin-bottom: 16px;
  border: none;
  border-radius: 50px;
  background: #4d96ff;
  color: white;
  box-shadow: 0 6px 0 #2f6fd1;
  cursor: pointer;
}

.replay-btn:active {
  transform: translateY(4px);
  box-shadow: 0 2px 0 #2f6fd1;
}

/* Without this, a disabled button (播放中, or before the first playback)
   looked pixel-identical to the enabled state — same color, same
   cursor:pointer set above overriding the browser's own disabled cursor —
   so it still looked tappable even though clicks were ignored. iOS Safari
   also flashes its own gray tap-highlight overlay on tap regardless of the
   disabled attribute, which read as "the button did something" even though
   the click was actually a no-op — -webkit-tap-highlight-color suppresses
   that specifically for the disabled state. */
.replay-btn:disabled {
  background: #b8c9de;
  box-shadow: 0 6px 0 #8fa0b5;
  -webkit-tap-highlight-color: transparent;
  cursor: not-allowed;
}

.replay-btn:disabled:active {
  transform: none;
  box-shadow: 0 6px 0 #8fa0b5;
}

/* Mole board */
.mole-board-wrap {
  position: relative;
  width: 100%;
  max-width: 640px;
}

/* One-shot mallet swing spawned at the tap point on every hole click —
   independent of correct/wrong outcome, which is shown separately via the
   hole's own glow/shake. Removed from the DOM once the animation ends. */
.mallet-hit {
  position: absolute;
  /* Matches the mallet's native 100x100 size (same as --hammer-cursor) so
     the swing animation isn't visibly smaller than the resting cursor. The
     margins are NOT just "center the box on the tap point" — the mallet
     head (bottom-center of the head rect, local ~(50,48) in the 100x100
     SVG) needs to land exactly on the tap point at the animation's final
     rotate(10deg) frame (pivoting around transform-origin 32% 92%), so the
     box offset is solved backwards from that rotated head position, not
     from the box's own geometric center or the cursor's hotspot.
     See scratchpad calc: rotate (50,48) by 10deg around (32,92) -> land at
     tap point => margin-left/top = -(that rotated point). */
  width: 100px;
  height: 100px;
  margin-left: -57px;
  margin-top: -52px;
  background-image: var(--mallet-svg);
  background-size: contain;
  background-repeat: no-repeat;
  transform-origin: 32% 92%;
  pointer-events: none;
  z-index: 20;
  animation: mallet-swing 0.3s ease-out forwards;
}

@keyframes mallet-swing {
  0% { transform: rotate(-55deg) scale(1); opacity: 1; }
  55% { transform: rotate(10deg) scale(1.08); opacity: 1; }
  100% { transform: rotate(10deg) scale(1); opacity: 0; }
}

.mole-board {
  position: relative;
  width: 100%;
  aspect-ratio: 4 / 3;
  background: #d9c290;
  border-radius: 24px;
  box-shadow: inset 0 4px 12px rgba(0,0,0,0.15);
  cursor: var(--hammer-cursor);
}

.countdown-display {
  position: absolute;
  inset: 0;
  display: none;
  align-items: center;
  justify-content: center;
  font-size: clamp(56px, 14vw, 96px);
  font-weight: bold;
  color: white;
  text-shadow: 0 4px 12px rgba(0,0,0,0.4);
  background: rgba(0,0,0,0.25);
  border-radius: 24px;
  pointer-events: none;
}

.countdown-display.visible {
  display: flex;
}

/* The hole marker: a completely separate, always-present layer — fixed
   size, fixed position, identical in every state (idle / revealed / tried /
   sinking). Previously the "hole" was just .mole-hole's own background,
   which meant it inherited whatever size/position .mole-hole.active grew to
   (bigger, to make the revealed mole+staff card more legible) — so the
   visible hole itself appeared to jump in size and position between states.
   Decoupling it here means the mole art (in .mole-hole) can be as big as it
   wants without ever moving or resizing the hole it's supposed to be
   emerging from/sinking into. Rendered once per slot by renderMoleBoard(),
   never touched again by any game-state class toggle. */
.mole-hole-marker {
  position: absolute;
  width: 16%;
  aspect-ratio: 1 / 1;
  transform: translate(-50%, -50%);
  border-radius: 50%;
  background: #3d2b1a;
  box-shadow: inset 0 6px 10px rgba(0,0,0,0.4);
  pointer-events: none;
}

/* Idle hole: the interactive button itself has no visual of its own now
   (the marker above provides it) — sized to match the marker only so its
   hit-target lines up while idle. */
.mole-hole {
  position: absolute;
  width: 16%;
  aspect-ratio: 1 / 1;
  transform: translate(-50%, -50%);
  border: none;
  outline: none;
  padding: 0;
  border-radius: 50%;
  background: transparent;
}

/* Active hole: this question's 4 live targets — wider, shows the
   mole+staff card art with no circular clipping so the staff renders
   fully instead of being cropped by the hole shape. Sits on top of (and
   deliberately larger than) the fixed-size marker underneath. */
.mole-hole.active {
  width: 22%;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  overflow: visible;
  background: transparent;
  box-shadow: none;
  cursor: var(--hammer-cursor);
}

/* Labeled art's aspect ratio is taller than the default (extra room for the
   baked-in Do/Re/Mi text) — scaled down so its rendered height roughly
   matches the default art at 22%, since holeSlots' vertical spacing assumes
   that height and doesn't know which art variant is active. */
.mole-board.labels-on .mole-hole.active {
  width: 18.5%;
}

/* Re-derives the img's bottom-alignment margin (see .mole-hole.active img
   below) for the narrower labels-on box. Must be recalculated whenever this
   box's width changes, since the margin is a % of the box's own (variable)
   width, not of the board — measured empirically the same way as the
   default value (getBoundingClientRect(), not a closed-form formula; see
   that comment for why). */
.mole-board.labels-on .mole-hole.active img {
  margin-bottom: 21.52%;
}

.mole-hole.active img {
  width: 100%;
  height: auto;
  display: block;
  /* Exactly aligns the img's bottom edge with the fixed-size hole marker's
     bottom edge (both centered on the same point via translate(-50%,-50%)).
     POSITIVE margin-bottom shifts the img up here — with align-items:
     flex-end, the margin box's edge aligns to the container's bottom, so a
     positive margin pulls the visible border-box up away from that edge.
     Not a clean closed-form % (which would be (22-16)/(2*22) ≈ 13.64% if
     this box were truly square): .mole-hole.active is a flex container
     whose own height doesn't actually honor aspect-ratio:1/1 the way the
     plain (non-flex) idle .mole-hole/.mole-hole-marker do — its real height
     comes out taller, and margin-bottom on the img itself is IN that height
     calculation too, so bumping the margin also grows the container height,
     which is why this needed 3 rounds of measure-and-adjust with
     getBoundingClientRect() to converge on the value below (img.bottom ==
     marker.bottom to within 1px) instead of a single formula. */
  margin-bottom: 18.72%;
  filter: drop-shadow(0 6px 8px rgba(0,0,0,0.3));
  transition: transform 0.15s ease;
  /* Promotes each hole's image to its own compositing layer so the
     mole-pop/mole-shake animation (transform + this filter) on the tapped
     hole repaints in isolation instead of visually jittering neighboring,
     untouched hole images — a known WebKit/Safari compositing artifact when
     several filtered/animated siblings share an unpromoted paint region. */
  will-change: transform;
  /* Declared explicitly (not just inherited from .mole-hole.active) because
     the drop-shadow filter above creates its own compositing layer, which
     can make a custom-image cursor silently disappear over the img even
     though it works fine over the rest of the hole's hit area. */
  cursor: var(--hammer-cursor);
  /* Runs once automatically since revealHoles() creates a fresh <img> each
     round — rises up out of the hole with a little overshoot bounce
     instead of just instantly appearing. Deliberately does NOT touch
     opacity (unlike an earlier attempt at this) — if the animation ever
     fails to progress for any reason, the image stays fully visible just
     mis-transformed, rather than risking it getting stuck invisible. */
  animation: mole-emerge 0.35s cubic-bezier(0.34, 1.56, 0.64, 1) both;
}

@keyframes mole-emerge {
  0% { transform: translateY(70%) scale(0.7); }
  100% { transform: translateY(0) scale(1); }
}

.mole-hole.correct img {
  filter: drop-shadow(0 0 10px #2ecc71) drop-shadow(0 6px 8px rgba(0,0,0,0.3));
  animation: mole-pop 0.4s ease;
}

@keyframes mole-pop {
  0% { transform: scale(0.7); }
  60% { transform: scale(1.15); }
  100% { transform: scale(1); }
}

.mole-hole.wrong img {
  animation: mole-shake 0.4s ease;
}

@keyframes mole-shake {
  0%, 100% { transform: rotate(0deg); }
  25% { transform: rotate(-6deg); }
  75% { transform: rotate(6deg); }
}

/* Plays after the correct/wrong feedback (mole-pop/mole-shake) has already
   shown, right before the round advances — sinks the mole back down into
   the hole. Mirrors mole-emerge exactly (same duration/easing/transform
   magnitude, reversed) so the appear and disappear motions match. Selector
   is deliberately MORE specific (three classes) than .mole-hole.correct/
   .wrong img (two classes) so it reliably overrides whichever feedback
   animation was playing, regardless of stylesheet order. Opacity only
   reaches 0 at the very end via forwards-fill, not at the start — if this
   animation ever fails to progress, the mole just stays visible a moment
   longer instead of getting stuck invisible. */
.mole-hole.active.sinking img {
  animation: mole-sink 0.35s cubic-bezier(0.34, 1.56, 0.64, 1) forwards;
}

@keyframes mole-sink {
  0% { transform: translateY(0) scale(1); opacity: 1; }
  100% { transform: translateY(70%) scale(0.7); opacity: 0; }
}

.mole-hole.tried img {
  opacity: 0.5;
}

.mole-hole:disabled,
.mole-hole.disabled {
  cursor: not-allowed;
}

/* Results */
.score-summary {
  font-size: clamp(18px, 3.5vw, 24px);
  background: white;
  border-radius: 16px;
  padding: 20px 28px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.08);
  margin-bottom: 20px;
}

.result-count {
  font-weight: bold;
  font-size: clamp(28px, 5vw, 36px);
}

.result-comment {
  font-size: clamp(20px, 4vw, 28px);
  font-weight: bold;
  color: #ff9f43;
  margin: 8px 0 20px;
}