/* =========================================================
   Digital Abacus Tool – abacus.css
   Theme: Deep Forest Green + Antique Gold
   ========================================================= */

@import url('https://fonts.googleapis.com/css2?family=Cinzel+Decorative:wght@400;700;900&family=Cinzel:wght@400;500;600;700&family=IM+Fell+English:ital@0;1&display=swap');

/* ── CSS Custom Properties ─────────────────────────────── */
.dat-wrapper {
  --dat-bg:           #0b2010;
  --dat-bg-2:         #0f2d15;
  --dat-bg-3:         #143319;
  --dat-bg-card:      #0d2613;
  --dat-bg-deep:      #071509;
  --dat-gold:         #d4a017;
  --dat-gold-light:   #f0c040;
  --dat-gold-pale:    #fde68a;
  --dat-gold-dark:    #a07810;
  --dat-green-bright: #22c55e;
  --dat-green-mid:    #16a34a;
  --dat-green-dim:    #166534;
  --dat-text:         #d4a017;
  --dat-text-dim:     #a07810;
  --dat-text-muted:   #6b5b1e;
  --dat-border:       #2d5a1e;
  --dat-border-gold:  #a07810;
  --dat-shadow:       0 4px 24px rgba(0,0,0,.6);
  --dat-shadow-gold:  0 0 16px rgba(212,160,23,.35);
  --dat-radius:       12px;
  --dat-radius-sm:    6px;
  --dat-bead-upper:   #d4a017;
  --dat-bead-upper-act: #f0c040;
  --dat-bead-lower:   #22c55e;
  --dat-bead-lower-act: #86efac;
  --dat-rod:          #2d5a1e;
  --dat-font-display: 'Cinzel Decorative', serif;
  --dat-font-body:    'Cinzel', serif;
  --dat-font-alt:     'IM Fell English', serif;
  --dat-transition:   .18s cubic-bezier(.4,0,.2,1);
}

/* Light theme override */
.dat-wrapper.dat-light {
  --dat-bg:           #f5f0dc;
  --dat-bg-2:         #ede8cc;
  --dat-bg-3:         #e0d8b0;
  --dat-bg-card:      #faf7e8;
  --dat-bg-deep:      #d4c98a;
  --dat-text:         #1a4d2e;
  --dat-text-dim:     #2d6a3f;
  --dat-text-muted:   #5a7d50;
  --dat-border:       #b8c88a;
  --dat-border-gold:  #a07810;
  --dat-bead-lower:   #1a4d2e;
  --dat-bead-lower-act: #2d8a4e;
  --dat-rod:          #8a9a60;
}

/* ── Reset & Box ─────────────────────────────────────────── */
.dat-wrapper *, .dat-wrapper *::before, .dat-wrapper *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* ── Wrapper ─────────────────────────────────────────────── */
.dat-wrapper {
  background: var(--dat-bg);
  background-image:
    radial-gradient(ellipse 80% 60% at 50% 0%, rgba(34,197,94,.08) 0%, transparent 70%),
    repeating-linear-gradient(
      0deg,
      transparent,
      transparent 39px,
      rgba(45,90,30,.15) 39px,
      rgba(45,90,30,.15) 40px
    );
  color: var(--dat-text);
  font-family: var(--dat-font-body);
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 0 40px;
  border: 2px solid var(--dat-border-gold);
  border-radius: var(--dat-radius);
  overflow: hidden;
  box-shadow: var(--dat-shadow), var(--dat-shadow-gold);
  position: relative;
}

/* Decorative corner ornaments */
.dat-wrapper::before,
.dat-wrapper::after {
  content: '✦';
  position: absolute;
  top: 10px;
  font-size: 1.2rem;
  color: var(--dat-gold);
  opacity: .6;
  pointer-events: none;
}
.dat-wrapper::before { left: 14px; }
.dat-wrapper::after  { right: 14px; }

/* ── Header ──────────────────────────────────────────────── */
.dat-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 28px 16px;
  background: var(--dat-bg-deep);
  border-bottom: 2px solid var(--dat-border-gold);
  gap: 12px;
  flex-wrap: wrap;
}

.dat-logo { display: flex; align-items: center; gap: 14px; }

.dat-logo-icon {
  font-size: 2.8rem;
  color: var(--dat-gold-light);
  line-height: 1;
  text-shadow: 0 0 20px rgba(212,160,23,.6);
  animation: dat-glow-pulse 3s ease-in-out infinite;
}

@keyframes dat-glow-pulse {
  0%,100% { text-shadow: 0 0 20px rgba(212,160,23,.6); }
  50%      { text-shadow: 0 0 36px rgba(240,192,64,.9), 0 0 60px rgba(240,192,64,.4); }
}

.dat-title {
  font-family: var(--dat-font-display);
  font-size: clamp(1rem, 3vw, 1.7rem);
  color: var(--dat-gold-light);
  letter-spacing: .06em;
  line-height: 1.1;
}

.dat-subtitle {
  font-family: var(--dat-font-alt);
  font-size: .78rem;
  color: var(--dat-text-muted);
  font-style: italic;
  letter-spacing: .12em;
}

.dat-controls-top { display: flex; gap: 8px; flex-shrink: 0; }

/* ── Buttons ─────────────────────────────────────────────── */
.dat-btn {
  font-family: var(--dat-font-body);
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .05em;
  border: 1.5px solid var(--dat-border-gold);
  border-radius: var(--dat-radius-sm);
  cursor: pointer;
  transition: var(--dat-transition);
  position: relative;
  overflow: hidden;
  background: var(--dat-bg-3);
  color: var(--dat-gold);
  padding: 8px 14px;
  white-space: nowrap;
}
.dat-btn::before {
  content: '';
  position: absolute; inset: 0;
  background: linear-gradient(135deg, rgba(212,160,23,.15), transparent);
  opacity: 0;
  transition: opacity var(--dat-transition);
}
.dat-btn:hover::before { opacity: 1; }
.dat-btn:hover {
  border-color: var(--dat-gold-light);
  color: var(--dat-gold-light);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(212,160,23,.25);
}
.dat-btn:active { transform: translateY(0); }

.dat-btn--sm { padding: 6px 10px; font-size: .75rem; }

.dat-btn--op {
  background: linear-gradient(135deg, #0f3320, var(--dat-bg-3));
  border-color: var(--dat-green-dim);
  color: var(--dat-green-bright);
}
.dat-btn--op:hover {
  border-color: var(--dat-green-bright);
  color: #fff;
  background: linear-gradient(135deg, var(--dat-green-dim), #0f3320);
  box-shadow: 0 4px 14px rgba(34,197,94,.3);
}

.dat-btn--mem {
  background: linear-gradient(135deg, #1e1a06, var(--dat-bg-3));
  border-color: var(--dat-gold-dark);
  color: var(--dat-gold);
}

.dat-btn--adv {
  background: linear-gradient(135deg, #1a0d2e, var(--dat-bg-3));
  border-color: #5b2d8a;
  color: #c084fc;
}
.dat-btn--adv:hover { border-color: #a855f7; color: #e9d5ff; }

.dat-btn--quick { border-color: #1d4c4c; color: #2dd4bf; }
.dat-btn--quick:hover { border-color: #2dd4bf; }

.dat-btn--num {
  font-family: var(--dat-font-display);
  font-size: 1.1rem;
  padding: 12px 0;
  background: var(--dat-bg-card);
  border-color: var(--dat-border);
  text-align: center;
}
.dat-btn--num:hover { background: var(--dat-bg-3); }

.dat-btn--dot, .dat-btn--back, .dat-btn--negate {
  font-size: .9rem;
  color: var(--dat-text-dim);
}
.dat-btn--enter {
  background: linear-gradient(135deg, var(--dat-gold-dark), var(--dat-gold));
  color: var(--dat-bg-deep);
  font-weight: 700;
  border-color: var(--dat-gold-light);
}
.dat-btn--enter:hover { background: linear-gradient(135deg, var(--dat-gold), var(--dat-gold-light)); }

.dat-btn--set {
  background: linear-gradient(90deg, var(--dat-green-dim), var(--dat-green-mid));
  color: #fff;
  border-color: var(--dat-green-bright);
  padding: 10px 20px;
}
.dat-btn--set:hover { background: linear-gradient(90deg, var(--dat-green-mid), var(--dat-green-bright)); }

.dat-btn--quiz-new    { background: linear-gradient(135deg,#1a4d2e,#0b2010); color: var(--dat-gold-light); }
.dat-btn--quiz-check  { background: linear-gradient(135deg,#1e1a06,#0b2010); color: var(--dat-gold); }
.dat-btn--quiz-reveal { background: linear-gradient(135deg,#1a0d2e,#0b2010); color: #c084fc; }

/* ── Display Section ─────────────────────────────────────── */
.dat-display-section { padding: 20px 28px 0; }

.dat-display-card {
  background: var(--dat-bg-deep);
  border: 1.5px solid var(--dat-border-gold);
  border-radius: var(--dat-radius);
  padding: 16px 20px;
  position: relative;
  overflow: hidden;
}
.dat-display-card::after {
  content: '';
  position: absolute; inset: 0;
  background: linear-gradient(135deg, rgba(212,160,23,.04) 0%, transparent 60%);
  pointer-events: none;
}

.dat-display-labels {
  display: flex; justify-content: space-between;
  font-size: .65rem; letter-spacing: .15em;
  color: var(--dat-text-muted); margin-bottom: 6px;
  text-transform: uppercase;
}

.dat-display-row {
  display: flex; align-items: center;
  justify-content: space-between; gap: 12px;
  flex-wrap: wrap;
}

.dat-value-big {
  font-family: var(--dat-font-display);
  font-size: clamp(1.8rem, 5vw, 3.2rem);
  color: var(--dat-gold-light);
  text-shadow: 0 0 24px rgba(240,192,64,.5);
  letter-spacing: .04em;
  transition: all .3s;
  word-break: break-all;
}

.dat-value-big.dat-pulse {
  animation: dat-value-pulse .4s ease;
}
@keyframes dat-value-pulse {
  0%   { transform: scale(1); }
  40%  { transform: scale(1.06); text-shadow: 0 0 40px rgba(240,192,64,.8); }
  100% { transform: scale(1); }
}

.dat-expression {
  font-family: var(--dat-font-alt);
  font-style: italic;
  font-size: clamp(.85rem, 2vw, 1.1rem);
  color: var(--dat-text-dim);
  text-align: right;
  flex: 1;
  word-break: break-all;
}

.dat-place-values {
  display: flex; flex-wrap: wrap; gap: 4px; margin-top: 10px;
}
.dat-place-chip {
  font-size: .65rem; padding: 2px 6px;
  border: 1px solid var(--dat-border);
  border-radius: 3px;
  background: var(--dat-bg-3);
  color: var(--dat-text-dim);
  letter-spacing: .05em;
  transition: var(--dat-transition);
}
.dat-place-chip.dat-active {
  border-color: var(--dat-gold);
  color: var(--dat-gold-light);
  background: rgba(212,160,23,.12);
}

/* ── Hint Bar ────────────────────────────────────────────── */
.dat-hint-bar {
  display: flex; align-items: center; gap: 10px;
  background: rgba(212,160,23,.07);
  border-top: 1px solid rgba(212,160,23,.2);
  border-bottom: 1px solid rgba(212,160,23,.2);
  padding: 10px 28px;
  margin-top: 14px;
  flex-wrap: wrap;
}
.dat-hint-icon { font-size: 1.1rem; flex-shrink: 0; }
.dat-hint-text {
  font-family: var(--dat-font-alt);
  font-style: italic;
  font-size: .82rem;
  color: var(--dat-gold);
  flex: 1;
  line-height: 1.4;
}
.dat-hint-next {
  font-family: var(--dat-font-body);
  font-size: .72rem;
  background: none;
  border: 1px solid var(--dat-border-gold);
  color: var(--dat-text-dim);
  border-radius: 4px;
  padding: 4px 10px;
  cursor: pointer;
  transition: var(--dat-transition);
}
.dat-hint-next:hover { color: var(--dat-gold); border-color: var(--dat-gold); }

/* ── Abacus Frame ────────────────────────────────────────── */
.dat-abacus-section { padding: 20px 28px 0; }

.dat-abacus-frame {
  position: relative;
  background: linear-gradient(180deg, #0a1f0c 0%, #0d2613 100%);
  border: 2.5px solid var(--dat-border-gold);
  border-radius: var(--dat-radius);
  overflow-x: auto;
  overflow-y: hidden;
  padding: 0 16px;
}

.dat-abacus-top-bar,
.dat-abacus-bottom-bar {
  height: 18px;
  background: linear-gradient(90deg, var(--dat-gold-dark), var(--dat-gold), var(--dat-gold-dark));
  border-radius: 4px;
  box-shadow: 0 2px 8px rgba(0,0,0,.5), inset 0 1px 0 rgba(255,255,255,.2);
}
.dat-abacus-top-bar  { margin-bottom: 0; }
.dat-abacus-bottom-bar { margin-top: 0; }

.dat-abacus-divider {
  height: 6px;
  background: linear-gradient(90deg, var(--dat-gold-dark), var(--dat-gold-light), var(--dat-gold-dark));
  box-shadow: 0 0 12px rgba(212,160,23,.4), inset 0 1px 0 rgba(255,255,255,.3);
  z-index: 2;
  position: relative;
}

.dat-abacus-left-post,
.dat-abacus-right-post {
  position: absolute;
  top: 0; bottom: 0;
  width: 16px;
  background: linear-gradient(180deg, var(--dat-gold-dark), var(--dat-gold), var(--dat-gold-dark));
  border-radius: 3px;
}
.dat-abacus-left-post  { left: 0; }
.dat-abacus-right-post { right: 0; }

.dat-abacus-body {
  display: flex;
  justify-content: center;
  align-items: stretch;
  gap: 0;
  padding: 0;
  min-height: 220px;
  position: relative;
}

/* ── Rod ─────────────────────────────────────────────────── */
.dat-rod {
  display: flex;
  flex-direction: column;
  align-items: center;
  flex: 1;
  min-width: 36px;
  max-width: 64px;
  position: relative;
  padding: 0 2px;
  cursor: pointer;
}
.dat-rod:hover .dat-rod-shaft { background: var(--dat-green-dim); }

.dat-rod-shaft {
  position: absolute;
  top: 0; bottom: 0;
  width: 5px;
  background: var(--dat-rod);
  left: 50%; transform: translateX(-50%);
  border-radius: 3px;
  transition: background var(--dat-transition);
  z-index: 0;
}

/* Sections */
.dat-rod-upper { display: flex; flex-direction: column; align-items: center; flex: 0 0 auto; padding: 8px 0 4px; position: relative; z-index: 1; }
.dat-rod-lower { display: flex; flex-direction: column; align-items: center; flex: 0 0 auto; padding: 4px 0 8px; position: relative; z-index: 1; }

/* ── Bead ─────────────────────────────────────────────────── */
.dat-bead {
  width: clamp(26px, 4vw, 44px);
  height: clamp(18px, 2.5vw, 28px);
  border-radius: 50%;
  cursor: pointer;
  transition: transform .18s cubic-bezier(.34,1.56,.64,1), background .18s, box-shadow .18s;
  position: relative;
  z-index: 2;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}
.dat-bead::after {
  content: '';
  position: absolute;
  top: 18%; left: 15%;
  width: 35%; height: 30%;
  background: rgba(255,255,255,.25);
  border-radius: 50%;
}

/* Upper beads */
.dat-bead--upper {
  background: radial-gradient(circle at 35% 35%, var(--dat-gold-light), var(--dat-gold-dark));
  box-shadow: 0 2px 6px rgba(0,0,0,.4), inset 0 1px 0 rgba(255,255,255,.2);
  margin: 2px 0;
}
.dat-bead--upper.dat-active {
  background: radial-gradient(circle at 35% 35%, #fff4c2, var(--dat-gold));
  box-shadow: 0 0 14px rgba(240,192,64,.7), 0 2px 6px rgba(0,0,0,.4);
  transform: translateY(6px) scale(1.06);
}
.dat-bead--upper:hover { filter: brightness(1.2); }

/* Lower beads */
.dat-bead--lower {
  background: radial-gradient(circle at 35% 35%, #4ade80, #166534);
  box-shadow: 0 2px 6px rgba(0,0,0,.4), inset 0 1px 0 rgba(255,255,255,.15);
  margin: 2px 0;
}
.dat-bead--lower.dat-active {
  background: radial-gradient(circle at 35% 35%, #bbf7d0, #22c55e);
  box-shadow: 0 0 14px rgba(34,197,94,.6), 0 2px 6px rgba(0,0,0,.4);
  transform: translateY(-6px) scale(1.06);
}
.dat-bead--lower:hover { filter: brightness(1.2); }

/* Rod labels */
.dat-rod-labels {
  display: flex; justify-content: center;
  gap: 0;
  margin-top: 6px;
}
.dat-rod-label {
  flex: 1; min-width: 36px; max-width: 64px;
  text-align: center;
  font-size: .6rem;
  color: var(--dat-text-muted);
  letter-spacing: .02em;
  font-family: var(--dat-font-body);
}

/* ── Operations Section ──────────────────────────────────── */
.dat-ops-section { padding: 20px 28px 0; }

.dat-ops-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin-bottom: 16px;
}

.dat-ops-group {
  background: var(--dat-bg-card);
  border: 1px solid var(--dat-border);
  border-radius: var(--dat-radius);
  padding: 12px 14px;
}

.dat-group-label {
  display: block;
  font-size: .65rem;
  letter-spacing: .15em;
  text-transform: uppercase;
  color: var(--dat-text-muted);
  margin-bottom: 8px;
}

.dat-btn-row {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 6px;
}

.dat-mem-display {
  margin-top: 8px;
  font-size: .75rem;
  color: var(--dat-text-muted);
  font-family: var(--dat-font-alt);
  font-style: italic;
}
.dat-mem-display span { color: var(--dat-gold); font-style: normal; }

.dat-operand-row {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  background: var(--dat-bg-card);
  border: 1px solid var(--dat-border);
  border-radius: var(--dat-radius);
  padding: 12px 14px;
}

.dat-operand-label {
  font-size: .75rem; color: var(--dat-text-dim); white-space: nowrap;
}

.dat-operand-input {
  flex: 1; min-width: 120px;
  background: var(--dat-bg-deep);
  border: 1.5px solid var(--dat-border-gold);
  border-radius: var(--dat-radius-sm);
  color: var(--dat-gold);
  font-family: var(--dat-font-display);
  font-size: 1rem;
  padding: 8px 12px;
  outline: none;
  transition: border-color var(--dat-transition);
}
.dat-operand-input:focus { border-color: var(--dat-gold-light); }
.dat-operand-input::placeholder { color: var(--dat-text-muted); font-size: .8rem; font-family: var(--dat-font-body); }

/* ── Number Pad ──────────────────────────────────────────── */
.dat-numpad-section {
  padding: 20px 28px 0;
}

.dat-numpad {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
  max-width: 420px;
  margin-bottom: 10px;
}

.dat-numpad-display {
  font-family: var(--dat-font-display);
  font-size: 1.4rem;
  color: var(--dat-gold-light);
  letter-spacing: .08em;
  min-height: 2rem;
  padding: 6px 12px;
  border-bottom: 2px solid var(--dat-border-gold);
  display: inline-block;
}

/* ── Quiz Section ────────────────────────────────────────── */
.dat-quiz-section {
  margin: 20px 28px 0;
  background: var(--dat-bg-card);
  border: 1.5px solid var(--dat-border-gold);
  border-radius: var(--dat-radius);
  overflow: hidden;
}

.dat-quiz-header {
  display: flex; align-items: center; justify-content: space-between;
  flex-wrap: wrap; gap: 8px;
  padding: 12px 16px;
  background: var(--dat-bg-deep);
  border-bottom: 1px solid var(--dat-border-gold);
}

.dat-quiz-title {
  font-family: var(--dat-font-display);
  font-size: 1rem;
  color: var(--dat-gold-light);
}

.dat-quiz-meta {
  font-size: .78rem;
  color: var(--dat-text-dim);
}
.dat-quiz-meta span { color: var(--dat-gold); font-family: var(--dat-font-display); }

.dat-quiz-body { padding: 16px; }

.dat-quiz-question {
  font-family: var(--dat-font-display);
  font-size: clamp(1.1rem, 3vw, 1.5rem);
  color: var(--dat-gold-light);
  margin-bottom: 8px;
  min-height: 2.5rem;
  text-align: center;
}

.dat-quiz-hint {
  font-family: var(--dat-font-alt);
  font-style: italic;
  font-size: .82rem;
  color: var(--dat-text-dim);
  min-height: 1.4rem;
  text-align: center;
  margin-bottom: 12px;
}

.dat-quiz-btns {
  display: flex; flex-wrap: wrap; gap: 8px; justify-content: center;
  margin-bottom: 12px;
}

.dat-quiz-feedback {
  text-align: center;
  font-family: var(--dat-font-display);
  font-size: 1rem;
  min-height: 1.6rem;
  transition: var(--dat-transition);
}
.dat-quiz-feedback.dat-correct { color: var(--dat-green-bright); }
.dat-quiz-feedback.dat-wrong   { color: #f87171; }

/* ── History Section ─────────────────────────────────────── */
.dat-history-section {
  margin: 20px 28px 0;
  background: var(--dat-bg-card);
  border: 1px solid var(--dat-border);
  border-radius: var(--dat-radius);
}

.dat-history-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 10px 14px;
  border-bottom: 1px solid var(--dat-border);
}

.dat-history-title {
  font-family: var(--dat-font-body);
  font-size: .88rem;
  color: var(--dat-gold);
  letter-spacing: .05em;
}

.dat-history-list {
  max-height: 200px;
  overflow-y: auto;
  padding: 6px 0;
}

.dat-history-empty {
  text-align: center;
  color: var(--dat-text-muted);
  font-family: var(--dat-font-alt);
  font-style: italic;
  padding: 20px;
  font-size: .82rem;
}

.dat-history-item {
  display: flex; align-items: center; justify-content: space-between;
  padding: 6px 14px;
  border-bottom: 1px solid rgba(45,90,30,.4);
  font-size: .78rem;
  gap: 8px;
  cursor: pointer;
  transition: background var(--dat-transition);
}
.dat-history-item:hover { background: rgba(212,160,23,.07); }
.dat-history-item:last-child { border-bottom: none; }

.dat-history-expr { color: var(--dat-text-dim); font-family: var(--dat-font-alt); font-style: italic; flex: 1; }
.dat-history-result { color: var(--dat-gold); font-family: var(--dat-font-display); font-weight: 700; }
.dat-history-time { color: var(--dat-text-muted); font-size: .68rem; }

/* ── Step Explainer ──────────────────────────────────────── */
.dat-steps-section {
  margin: 20px 28px 0;
  background: var(--dat-bg-card);
  border: 1.5px solid var(--dat-border-gold);
  border-radius: var(--dat-radius);
  padding: 16px;
}
.dat-steps-title {
  font-family: var(--dat-font-body);
  font-size: .9rem;
  color: var(--dat-gold);
  margin-bottom: 12px;
}
.dat-step-item {
  display: flex; gap: 10px; margin-bottom: 10px; align-items: flex-start;
}
.dat-step-num {
  width: 24px; height: 24px; border-radius: 50%;
  background: var(--dat-gold-dark);
  color: var(--dat-bg-deep);
  font-family: var(--dat-font-display);
  font-size: .72rem;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
}
.dat-step-text {
  font-family: var(--dat-font-alt);
  font-style: italic;
  font-size: .82rem;
  color: var(--dat-text-dim);
  line-height: 1.5;
}

/* ── Guide Section ───────────────────────────────────────── */
.dat-guide-section { margin: 20px 28px 0; }

.dat-guide-details {
  border: 1px solid var(--dat-border);
  border-radius: var(--dat-radius);
  background: var(--dat-bg-card);
}

.dat-guide-summary {
  padding: 12px 16px;
  font-family: var(--dat-font-body);
  font-size: .85rem;
  color: var(--dat-gold);
  cursor: pointer;
  letter-spacing: .05em;
  user-select: none;
  list-style: none;
}
.dat-guide-summary::-webkit-details-marker { display: none; }
.dat-guide-summary::before { content: '▶ '; font-size: .7rem; transition: transform .2s; }
details[open] .dat-guide-summary::before { content: '▼ '; }

.dat-guide-body {
  padding: 0 16px 16px;
  border-top: 1px solid var(--dat-border);
}

.dat-guide-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
  margin-top: 12px;
}

.dat-guide-card {
  background: var(--dat-bg-3);
  border: 1px solid var(--dat-border);
  border-radius: var(--dat-radius-sm);
  padding: 12px;
}
.dat-guide-card h4 {
  font-family: var(--dat-font-body);
  font-size: .8rem;
  color: var(--dat-gold);
  margin-bottom: 6px;
}
.dat-guide-card p {
  font-family: var(--dat-font-alt);
  font-style: italic;
  font-size: .75rem;
  color: var(--dat-text-dim);
  line-height: 1.5;
}

/* ── Scrollbar ───────────────────────────────────────────── */
.dat-wrapper ::-webkit-scrollbar { width: 6px; height: 6px; }
.dat-wrapper ::-webkit-scrollbar-track { background: var(--dat-bg-deep); }
.dat-wrapper ::-webkit-scrollbar-thumb { background: var(--dat-border-gold); border-radius: 3px; }

/* ── Toast / Feedback ────────────────────────────────────── */
.dat-toast {
  position: fixed;
  bottom: 30px; right: 30px;
  background: var(--dat-bg-deep);
  border: 1.5px solid var(--dat-gold);
  border-radius: var(--dat-radius-sm);
  color: var(--dat-gold-light);
  font-family: var(--dat-font-body);
  font-size: .85rem;
  padding: 10px 20px;
  box-shadow: var(--dat-shadow-gold);
  z-index: 9999;
  animation: dat-toast-in .3s ease, dat-toast-out .3s ease 2.2s forwards;
  pointer-events: none;
}
@keyframes dat-toast-in  { from { opacity: 0; transform: translateY(16px); } }
@keyframes dat-toast-out { to   { opacity: 0; transform: translateY(8px);  } }

/* ── Responsive ──────────────────────────────────────────── */
@media (max-width: 768px) {
  .dat-header { padding: 14px 16px; }
  .dat-display-section,
  .dat-abacus-section,
  .dat-ops-section,
  .dat-numpad-section,
  .dat-quiz-section,
  .dat-history-section,
  .dat-steps-section,
  .dat-guide-section { padding-left: 12px; padding-right: 12px; }
  .dat-quiz-section,
  .dat-history-section,
  .dat-steps-section,
  .dat-guide-section { margin-left: 12px; margin-right: 12px; }
  .dat-hint-bar { padding: 10px 12px; }
  .dat-ops-grid { grid-template-columns: 1fr 1fr; }
  .dat-numpad { grid-template-columns: repeat(5, 1fr); }
}

@media (max-width: 480px) {
  .dat-logo-icon { font-size: 2rem; }
  .dat-title { font-size: .95rem; }
  .dat-ops-grid { grid-template-columns: 1fr; }
  .dat-numpad { grid-template-columns: repeat(4, 1fr); }
  .dat-abacus-frame { padding: 0 8px; }
  .dat-rod { min-width: 28px; }
  .dat-bead { width: 22px; height: 16px; }
  .dat-value-big { font-size: 1.8rem; }
}