:root {
  /* "Overworld" palette */
  --bg: #6fbfff;
  --card-bg: #fffaeb;
  --text: #2b1a0e;
  --text-muted: #8a6a45;
  --accent: #58b947;
  --accent-dark: #3f8a32;
  --warning: #fbd000;
  --warning-dark: #e0ae00;
  --success: #1e9e62;
  --danger: #e52521;
  --border: #ffd54a;
  --border-alt: #89ccff;
  --tile-bg: #fff3d6;
  --shadow: 0 8px 0 rgba(43, 26, 14, 0.15);
  color-scheme: light;
}

:root[data-theme="dark"] {
  /* "Underground" palette */
  --bg: #0a0a0a;
  --card-bg: #2b1c10;
  --text: #fdf3d8;
  --text-muted: #c9a876;
  --accent: #7ed957;
  --accent-dark: #58b947;
  --warning: #fbd000;
  --warning-dark: #c99a00;
  --success: #2ecc81;
  --danger: #ff5a52;
  --border: #5a3d1f;
  --border-alt: #1a1006;
  --tile-bg: #1a1006;
  --shadow: 0 8px 0 rgba(0, 0, 0, 0.5);
  color-scheme: dark;
}

* {
  box-sizing: border-box;
}

button,
input {
  font-family: inherit;
}

html,
body {
  margin: 0;
  padding: 0;
  height: 100%;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family:
    "Baloo 2",
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    Roboto,
    Helvetica,
    Arial,
    sans-serif;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 20px;
}

.screen {
  width: 100%;
  max-width: 480px;
}

.hidden {
  display: none !important;
}

.header-site {
  text-align: center;
  font-size: 5rem;
  color: #ffffff;
}

.theme-toggle-btn {
  position: fixed;
  top: 16px;
  right: 16px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1.5px solid var(--border);
  background: var(--card-bg);
  color: var(--text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  padding: 0;
  z-index: 10;
  -webkit-tap-highlight-color: transparent;
}

.theme-toggle-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.theme-icon {
  width: 20px;
  height: 20px;
  fill: currentColor;
}

/* ---------- Card (settings & results) ---------- */
.card {
  background: var(--card-bg);
  border-radius: 20px;
  box-shadow: var(--shadow);
  padding: 32px 28px;
}

h1 {
  margin: 0 0 4px;
  font-size: 1.6rem;
  font-weight: 700;
}

.subtitle {
  margin: 0 0 24px;
  color: var(--text-muted);
  font-size: 0.95rem;
}

.settings-group {
  margin-bottom: 24px;
}

.settings-group h2 {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-muted);
  margin: 0 0 12px;
}

.table-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
}

.table-chip {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 44px;
  border-radius: 10px;
  border: 1.5px solid var(--border);
  background: transparent;
  color: var(--text);
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  user-select: none;
  transition:
    background 0.15s,
    border-color 0.15s,
    color 0.15s;
}

.table-chip.selected {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.quick-btns {
  display: flex;
  gap: 8px;
  margin-top: 12px;
}

.btn-ghost {
  background: transparent;
  border: 1.5px solid var(--border);
  color: var(--text-muted);
  padding: 8px 14px;
  border-radius: 10px;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
}

.btn-ghost:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.toggle-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  font-size: 0.95rem;
  cursor: pointer;
  position: relative;
}

.toggle-row .hint {
  color: var(--text-muted);
  font-size: 0.8rem;
  display: block;
}

.toggle-row input[type="checkbox"] {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.toggle-switch {
  flex: 0 0 auto;
  width: 44px;
  height: 26px;
  border-radius: 999px;
  background: var(--border);
  position: relative;
  transition: background 0.15s;
}

.toggle-switch::after {
  content: "";
  position: absolute;
  top: 3px;
  left: 3px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #fff;
  transition: transform 0.15s;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
}

.toggle-row input:checked + .toggle-switch {
  background: var(--accent);
}

.toggle-row input:checked + .toggle-switch::after {
  transform: translateX(18px);
}

.slider-row {
  display: flex;
  align-items: center;
  gap: 14px;
}

input[type="range"] {
  flex: 1;
  accent-color: var(--accent);
}

.slider-value {
  font-weight: 700;
  min-width: 34px;
  text-align: right;
}

.problem-count {
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
  padding-top: 4px;
}

.btn-primary {
  width: 100%;
  background: var(--accent);
  color: #fff;
  border: none;
  padding: 15px;
  border-radius: 12px;
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.15s;
}

.btn-primary:hover {
  background: var(--accent-dark);
}

.btn-primary:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* ---------- Practice screen ---------- */
.practice-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
}

.top-bar {
  width: 100%;
}

.progress-info {
  display: flex;
  justify-content: space-between;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 6px;
  font-weight: 600;
}

.progress-track {
  width: 100%;
  height: 8px;
  border-radius: 999px;
  background: var(--border);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--success);
  width: 0%;
  transition: width 0.25s ease;
}

.timer-row {
  display: flex;
  align-items: center;
  gap: 16px;
}

.timer-wrap {
  position: relative;
  width: 96px;
  height: 96px;
}

.pause-btn {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1.5px solid var(--border);
  background: var(--card-bg);
  color: var(--text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

.pause-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.pause-icon {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

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

.timer-ring-bg {
  fill: none;
  stroke: var(--border-alt);
  stroke-width: 8;
}

.timer-ring-fg {
  fill: none;
  stroke: var(--accent);
  stroke-width: 8;
  stroke-linecap: round;
  stroke-dasharray: 326.7256;
  stroke-dashoffset: 0;
  transition:
    stroke-dashoffset 0.1s linear,
    stroke 0.15s;
}

.timer-number {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 1.8rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}

.problem-card {
  position: relative;
  width: 100%;
  background: var(--card-bg);
  border-radius: 20px;
  box-shadow: var(--shadow);
  padding: 28px 20px;
  text-align: center;
  min-height: 150px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  transition: background 0.15s;
}

.problem-card.flash-correct {
  background: color-mix(in srgb, var(--success) 18%, var(--card-bg));
}

.problem-card.flash-wrong {
  background: color-mix(in srgb, var(--danger) 18%, var(--card-bg));
}

.problem-card.is-paused .problem-text,
.problem-card.is-paused .answer-display,
.problem-card.is-paused .feedback {
  visibility: hidden;
}

.pause-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  background: var(--card-bg);
  border-radius: 20px;
}

.pause-overlay-title {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--text-muted);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.resume-btn {
  width: auto;
  padding: 12px 28px;
}

.problem-text {
  font-size: 2.6rem;
  font-weight: 800;
  letter-spacing: 0.02em;
  font-variant-numeric: tabular-nums;
}

.answer-display {
  min-height: 2.2rem;
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
}

.cursor {
  display: inline-block;
  margin-left: 2px;
  animation: blink 1s step-start infinite;
  color: var(--accent);
}

@keyframes blink {
  50% {
    opacity: 0;
  }
}

.feedback {
  min-height: 1.3rem;
  font-size: 0.95rem;
  font-weight: 700;
}

.feedback.correct {
  color: var(--success);
}
.feedback.wrong {
  color: var(--danger);
}

.numpad {
  width: 100%;
  max-width: 320px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  transition: opacity 0.15s;
}

.numpad.is-paused {
  opacity: 0.4;
  pointer-events: none;
}

.num-btn {
  height: 58px;
  border-radius: 14px;
  border: none;
  background: var(--card-bg);
  box-shadow: var(--shadow);
  color: var(--text);
  font-size: 1.4rem;
  font-weight: 700;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.num-btn:active {
  transform: scale(0.96);
}

.action-btn {
  background: var(--border);
  font-size: 1.2rem;
}

.submit-btn {
  background: var(--accent);
  color: #fff;
}

.hidden-input {
  position: absolute;
  opacity: 0;
  height: 0;
  width: 0;
  pointer-events: none;
}

.quit-btn {
  margin-top: 4px;
}

/* ---------- Results screen ---------- */
.stats-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin: 24px 0;
}

.stat {
  background: var(--tile-bg);
  border-radius: 14px;
  padding: 16px;
  text-align: center;
}

.stat-value {
  display: block;
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--accent);
}

.stat-label {
  display: block;
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 4px;
}

.trouble-section {
  margin-bottom: 20px;
}

.trouble-section h2 {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-muted);
  margin: 0 0 10px;
}

.trouble-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.trouble-chip {
  background: color-mix(in srgb, var(--danger) 14%, var(--card-bg));
  color: var(--danger);
  border-radius: 999px;
  padding: 6px 12px;
  font-size: 0.85rem;
  font-weight: 700;
}

.results-btns {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.print-only {
  display: none;
}

/* ---------- Print ---------- */
@media print {
  body {
    background: #fff;
    display: block;
    padding: 0;
    min-height: 0;
  }

  .theme-toggle-btn,
  #screen-settings,
  #screen-practice,
  .header-site,
  .results-btns {
    display: none !important;
  }

  #screen-results {
    max-width: none;
  }

  .card {
    box-shadow: none;
    border: 3px solid #000;
    background: #fff;
  }

  .print-only {
    display: block;
    text-align: center;
    margin-bottom: 20px;
  }

  .print-logo {
    font-size: 2rem;
    font-weight: 800;
    color: #000;
  }

  .print-date {
    color: #444;
    font-size: 0.9rem;
  }

  h1,
  .stat-value,
  .stat-label,
  .subtitle,
  .trouble-section h2 {
    color: #000 !important;
  }

  .stat {
    background: #f2f2f2;
  }

  .trouble-chip {
    background: #fff;
    border: 1.5px solid #000;
    color: #000;
  }
}