/* ── Phase Change & Latent Heat Simulator ────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:        #0d1117;
  --surface:   #161b27;
  --surface2:  #1f2535;
  --border:    #2a3050;
  --accent:    #26c6da;
  --accent-lo: rgba(38,198,218,.22);
  --green:     #3ddc84;
  --red:       #ff5555;
  --gold:      #f5c842;
  --text:      #dde3f0;
  --text-dim:  #6b7a99;
  --font:      'Segoe UI', system-ui, sans-serif;
  --mono:      'Courier New', monospace;
  --radius:    12px;
}

body { background: var(--bg); color: var(--text); font-family: var(--font); min-height: 100vh; padding: 0 16px; }
#app { max-width: 980px; margin: 0 auto; display: flex; flex-direction: column; gap: 14px; }

/* ── Header ────────────────────────────────────────────────────── */
header { text-align: center; padding: 4px 0; }
header h1 {
  font-size: 1.8rem; font-weight: 700;
  background: linear-gradient(120deg, #26c6da 0%, #4fc3f7 50%, #80deea 100%);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
}
.subtitle { color: var(--text-dim); font-size: 0.85rem; margin-top: 3px; }

/* ── Controls bar ──────────────────────────────────────────────── */
.controls-bar {
  display: flex; flex-wrap: wrap; align-items: center; gap: 14px;
  padding: 12px 16px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
}
.ctrl-group { display: flex; align-items: center; gap: 8px; }
.ctrl-label { font-size: 0.72rem; text-transform: uppercase; letter-spacing: .06em; color: var(--text-dim); white-space: nowrap; }

.pill-tabs { display: flex; background: var(--bg); border-radius: 8px; padding: 3px; gap: 2px; }
.pill {
  padding: 5px 13px; border: none; background: transparent; color: var(--text-dim);
  border-radius: 6px; cursor: pointer; font-size: 0.81rem;
  transition: background .18s, color .18s, box-shadow .18s;
}
.pill.active { background: var(--accent); color: #08242a; box-shadow: 0 0 12px var(--accent-lo); }
.pill:hover:not(.active) { background: var(--surface2); color: var(--text); }

/* ── Canvas card ───────────────────────────────────────────────── */
.canvas-card {
  width: 100%; background: var(--surface);
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 8px; position: relative; overflow-x: clip;
}
.canvas-card canvas { display: block; width: 100%; height: auto; cursor: default; touch-action: pan-y; }

/* ── Buttons ───────────────────────────────────────────────────── */
.btn {
  padding: 8px 18px; border: none; border-radius: 8px; cursor: pointer;
  font-size: 0.84rem; font-weight: 600; transition: filter .18s, box-shadow .18s, opacity .18s;
}
.btn:disabled { opacity: 0.38; cursor: not-allowed; }
.btn-primary { background: var(--accent); color: #08242a; }
.btn-primary:not(:disabled):hover { filter: brightness(1.12); box-shadow: 0 0 12px var(--accent-lo); }
.btn-ghost { background: var(--surface2); color: var(--text); border: 1px solid var(--border); }
.btn-ghost:hover { background: var(--border); }

/* ── Sim controls ─────────────────────────────────────────────── */
.sim-controls {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 14px 18px; display: flex; flex-direction: column; gap: 12px;
}
.sim-row { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; }
.sim-select-group { display: flex; align-items: center; gap: 10px; flex: 1; min-width: 200px; }
.sim-slider-group {
  display: flex; flex-direction: column; gap: 7px; min-width: 0;
  background: var(--bg); border: 1px solid var(--border);
  border-radius: 10px; padding: 10px 12px;
}
.sim-slider-label {
  font-size: 0.73rem; font-weight: 700; color: var(--text-dim);
  display: flex; align-items: center; justify-content: space-between; gap: 6px;
}
.sim-select {
  flex: 1; padding: 8px 12px; border: 2px solid var(--border); border-radius: 8px;
  background: var(--bg); color: var(--text); font-family: var(--font); font-size: 0.84rem;
  cursor: pointer; transition: border-color .18s;
}
.sim-select:focus { outline: none; border-color: var(--accent); }
.sim-slider {
  flex: 1; -webkit-appearance: none; appearance: none; height: 6px;
  background: rgba(255,255,255,.12); border-radius: 3px; outline: none;
  border: 1px solid rgba(255,255,255,.1);
}
.sim-slider::-webkit-slider-runnable-track {
  height: 6px; border-radius: 3px;
  background: linear-gradient(to right, var(--accent-lo), rgba(255,255,255,.12));
}
.sim-slider::-webkit-slider-thumb {
  -webkit-appearance: none; width: 18px; height: 18px; margin-top: -6px;
  border-radius: 50%; background: var(--accent); cursor: pointer;
  box-shadow: 0 0 8px var(--accent-lo);
  border: 2px solid rgba(255,255,255,.2);
}
.sim-slider::-moz-range-track {
  height: 6px; border-radius: 3px;
  background: linear-gradient(to right, var(--accent-lo), rgba(255,255,255,.12));
}
.sim-slider::-moz-range-thumb {
  width: 16px; height: 16px; border: 2px solid rgba(255,255,255,.2);
  border-radius: 50%; background: var(--accent); cursor: pointer;
}
.sim-slider-val {
  font-family: var(--mono); font-size: 0.9rem; font-weight: 700;
  color: var(--accent); min-width: 75px; text-align: right;
}

/* ── Readout row ───────────────────────────────────────────────── */
.readout-row {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(130px, 1fr)); gap: 8px;
}
.readout-card {
  background: var(--bg); border: 1px solid var(--border); border-radius: 8px;
  padding: 8px 12px; text-align: center;
}
.readout-label { font-size: 0.62rem; text-transform: uppercase; letter-spacing: .07em; color: var(--text-dim); margin-bottom: 3px; }
.readout-val { font-family: var(--mono); font-size: 1.15rem; font-weight: 700; color: var(--accent); }
.readout-val-sm { font-size: 0.82rem; }
.readout-unit { font-size: 0.68rem; color: var(--text-dim); margin-left: 2px; }

/* ── Explore mode ──────────────────────────────────────────────── */
.item-selector {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 14px 16px;
}
.is-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(155px, 1fr)); gap: 8px; margin-top: 10px; }
.is-btn {
  padding: 10px 14px; border: 2px solid var(--border); border-radius: 10px;
  background: var(--surface2); color: var(--text-dim); font-size: 0.82rem;
  font-weight: 600; cursor: pointer; text-align: left;
  transition: border-color .18s, color .18s, background .18s, box-shadow .18s;
}
.is-btn:hover { border-color: rgba(38,198,218,.45); color: var(--text); }
.is-btn.active { border-color: var(--accent); color: #fff; background: rgba(38,198,218,.15); box-shadow: 0 0 14px var(--accent-lo); }
.is-btn-name { display: block; font-size: 0.82rem; font-weight: 700; }
.is-btn-sym  { display: block; font-size: 0.68rem; color: var(--accent); margin-top: 2px; font-family: var(--mono); }

.item-info {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px 18px; display: flex; flex-direction: column; gap: 8px;
}
.ii-top { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.ii-name { font-size: 1.15rem; font-weight: 800; color: var(--text); }
.ii-cat-badge {
  font-size: 0.62rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: .07em; padding: 3px 10px; border-radius: 20px;
  background: var(--accent-lo); color: var(--accent);
}
.ii-desc { font-size: 0.85rem; color: var(--text-dim); line-height: 1.65; }

.formula-box {
  background: var(--bg); border: 1px solid var(--border); border-radius: 8px;
  padding: 10px 14px; display: flex; align-items: center; gap: 16px; flex-wrap: wrap;
}
.fb-formula { font-family: var(--mono); font-size: 1.1rem; font-weight: 700; color: var(--accent); }
.fb-unit { font-size: 0.78rem; color: var(--text-dim); }

.example-box {
  background: var(--surface2); border: 1px solid var(--border); border-radius: 8px;
  padding: 12px 14px;
}
.example-box h4 { font-size: 0.72rem; text-transform: uppercase; letter-spacing: .08em; color: var(--accent); margin-bottom: 8px; }
.example-box .ex-problem { font-size: 0.84rem; color: var(--text); margin-bottom: 8px; line-height: 1.6; }
.example-box .ex-step { font-size: 0.8rem; color: var(--text-dim); line-height: 1.6; padding: 2px 0; }
.example-box .ex-step strong { color: var(--green); font-family: var(--mono); }

/* ── Practice mode ─────────────────────────────────────────────── */
.practice-panel {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px 18px;
}
.pp-prompt { font-size: 0.92rem; font-weight: 600; color: var(--text); margin-bottom: 14px; line-height: 1.6; }
.pp-input-row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.pp-input {
  flex: 1; min-width: 120px; max-width: 220px;
  padding: 10px 14px; border: 2px solid var(--border); border-radius: 8px;
  background: var(--bg); color: var(--text); font-family: var(--mono);
  font-size: 1rem; font-weight: 700; transition: border-color .18s;
}
.pp-input:focus { outline: none; border-color: var(--accent); }
.pp-unit { font-size: 0.88rem; color: var(--text-dim); font-weight: 600; }
.pp-bottom { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-top: 14px; }
.feedback { font-size: 0.88rem; font-weight: 600; }
.feedback.ok  { color: var(--green); }
.feedback.err { color: var(--red); }

.solution-panel {
  background: var(--surface2); border: 1px solid var(--border); border-radius: 8px;
  padding: 14px 16px; margin-top: 12px;
}
.solution-panel h4 { font-size: 0.72rem; text-transform: uppercase; letter-spacing: .08em; color: var(--accent); margin-bottom: 8px; }
.sol-step { font-size: 0.82rem; color: var(--text-dim); line-height: 1.7; padding: 2px 0; }
.sol-step strong { color: var(--green); font-family: var(--mono); }

.practice-bar {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
  padding: 12px 16px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
}
.pbar-score { font-size: 0.84rem; color: var(--text-dim); margin-left: auto; white-space: nowrap; }
.pbar-score span { color: var(--text); font-weight: 700; }

/* ── Quiz panels ───────────────────────────────────────────────── */
.question-panel {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px 18px;
}
.qp-prompt { font-size: 0.88rem; font-weight: 600; color: var(--text); margin-bottom: 12px; line-height: 1.6; }
.answer-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.answer-btn {
  padding: 14px 16px; border: 2px solid var(--border); border-radius: 10px;
  background: var(--surface2); color: var(--text); font-size: 0.88rem;
  font-weight: 600; cursor: pointer; text-align: center;
  transition: border-color .18s, background .18s, color .18s, transform .12s;
}
.answer-btn:hover:not(.locked) { border-color: var(--accent); background: rgba(38,198,218,.06); }
.answer-btn.correct { border-color: var(--green); background: rgba(61,220,132,.12); color: var(--green); }
.answer-btn.wrong { border-color: var(--red); background: rgba(255,85,85,.08); color: var(--red); }
.answer-btn.locked { cursor: default; opacity: 0.6; }
.answer-btn.correct.locked { opacity: 1; }

.quiz-bar {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
  padding: 12px 16px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
}
.qbar-counter { display: flex; align-items: baseline; gap: 3px; background: var(--bg); border: 1px solid var(--border); border-radius: 8px; padding: 4px 12px; }
.qbar-q-label { font-size: 0.7rem; font-weight: 700; color: var(--accent); text-transform: uppercase; letter-spacing: .08em; }
.qbar-q-num { font-family: var(--mono); font-size: 1.3rem; font-weight: 700; color: var(--text); line-height: 1; }
.qbar-q-sep { font-size: 0.82rem; color: var(--text-dim); }
.qbar-q-total { font-family: var(--mono); font-size: 0.88rem; color: var(--text-dim); }
.quiz-feedback { font-size: 0.88rem; font-weight: 600; }
.quiz-feedback.ok  { color: var(--green); }
.quiz-feedback.err { color: var(--red); }

.quiz-result {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 20px 22px; display: flex; flex-direction: column; gap: 14px;
}
.qr-header { display: flex; align-items: flex-start; justify-content: space-between; }
.qr-title-wrap { display: flex; flex-direction: column; gap: 5px; }
.qr-title  { font-size: 1.1rem; font-weight: 700; color: var(--text); }
.qr-stars  { font-size: 1.2rem; letter-spacing: 3px; }
.qr-score-wrap { text-align: right; }
.qr-score { font-family: var(--mono); font-size: 2.2rem; font-weight: 700; line-height: 1; text-shadow: 0 0 14px currentColor; }
.qr-score.perfect { color: var(--gold); }
.qr-score.good { color: var(--green); }
.qr-score.poor { color: var(--red); }
.qr-verdict { font-size: 0.72rem; color: var(--text-dim); margin-top: 3px; }
.qr-rows { display: flex; flex-direction: column; gap: 7px; }
.qr-row {
  display: grid; grid-template-columns: 30px 1fr 26px; align-items: center; gap: 10px;
  background: var(--surface2); border: 1px solid var(--border); border-left-width: 3px;
  border-radius: 8px; padding: 9px 12px;
}
.qr-row.ok  { border-left-color: var(--green); }
.qr-row.err { border-left-color: var(--red); }
.qr-qnum { font-size: 0.72rem; font-weight: 700; color: var(--accent); }
.qr-detail { font-size: 0.78rem; color: var(--text-dim); }
.qr-detail strong { color: var(--text); }
.qr-mark { text-align: right; font-size: 1rem; font-weight: 700; }
.qr-row.ok .qr-mark { color: var(--green); }
.qr-row.err .qr-mark { color: var(--red); }

/* ── SEO Article ───────────────────────────────────────────────── */
.seo-article { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 22px 24px; line-height: 1.7; }
.seo-article h2 { font-size: 1.25rem; color: var(--text); margin-bottom: 12px; }
.seo-article h3 { font-size: 1.05rem; color: var(--accent); margin: 16px 0 6px; }
.seo-article p { font-size: 0.88rem; color: var(--text-dim); margin-bottom: 10px; }
.seo-article a { color: var(--accent); text-decoration: none; }
.seo-article a:hover { text-decoration: underline; }

.seo-table {
  width: 100%; border-collapse: collapse; margin: 10px 0 16px;
  font-size: 0.82rem; background: var(--bg);
  border: 1px solid var(--border); border-radius: 8px; overflow: hidden;
  table-layout: fixed;
}
.seo-table th, .seo-table td { word-wrap: break-word; overflow-wrap: break-word; padding: 8px 10px; text-align: left; border-bottom: 1px solid var(--border); }
.seo-table th { background: var(--surface2); color: var(--accent); font-weight: 700; font-size: 0.78rem; text-transform: uppercase; letter-spacing: .04em; }
.seo-table tr:last-child td { border-bottom: none; }
.seo-table td { color: var(--text-dim); }
.seo-table td:first-child { color: var(--text); font-weight: 600; }

/* ═══ Canvas feature toggles ═════ */
.canvas-toggles {
  position: absolute; top: 12px; left: 12px; z-index: 3;
  display: flex; flex-wrap: wrap; gap: 6px;
  background: rgba(13,17,30,0.7); backdrop-filter: blur(3px);
  border: 1px solid rgba(139,157,195,0.2); border-radius: 8px;
  padding: 6px 8px; max-width: 60%;
}
.cv-tog { display: inline-flex; align-items: center; gap: 5px; font-size: 0.74rem; color: var(--text-dim); cursor: pointer; user-select: none; padding: 2px 4px; border-radius: 4px; }
.cv-tog:hover { color: var(--text); }
.cv-tog input { accent-color: var(--accent); width: 14px; height: 14px; cursor: pointer; }

/* ═══ Slider cards — 3-column grid, vertical layout per card ═══════════════════════ */
.slider-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; align-items: start; }
.sim-slider-group .sim-slider { width: 100%; }
.stepper {
  display: flex; align-items: stretch; width: 100%;
  border: 1px solid var(--border); border-radius: 8px; overflow: hidden;
  background: var(--bg); height: 34px;
}
.step-btn {
  width: 34px; flex-shrink: 0; border: none; background: var(--surface2);
  color: var(--text-dim); font-size: 1.05rem; font-weight: 700;
  cursor: pointer; transition: background .15s, color .15s;
  display: flex; align-items: center; justify-content: center; padding: 0;
}
.step-btn:hover { background: var(--accent-lo); color: var(--accent); }
.step-btn:active { background: var(--accent); color: #08242a; }
.step-input {
  flex: 1; min-width: 0; border: none; background: var(--bg); color: var(--accent);
  font-family: var(--mono); font-size: 0.85rem; font-weight: 700;
  text-align: center; outline: none; padding: 0 4px; height: 100%;
  border-left: 1px solid var(--border); border-right: 1px solid var(--border);
}
.step-input:focus { background: var(--surface2); }
.step-input::-webkit-outer-spin-button, .step-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.step-input[type=number] { -moz-appearance: textfield; }

.sim-unit-badge { display: inline-block; padding: 1px 7px; border-radius: 10px; background: var(--accent-lo); color: var(--accent); font-size: 0.66rem; font-weight: 700; margin-left: 4px; }

/* ═══ Preset chips ═════════════════════════════════════ */
.preset-row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.preset-chips { display: flex; gap: 6px; flex-wrap: wrap; flex: 1; }
.preset-chip {
  padding: 5px 12px; border-radius: 20px;
  background: var(--surface2); border: 1px solid var(--border);
  color: var(--text-dim); font-size: 0.76rem; font-weight: 600;
  cursor: pointer; transition: border-color .15s, color .15s, background .15s;
}
.preset-chip:hover { border-color: var(--accent); color: var(--text); }
.preset-chip.active { background: var(--accent-lo); color: var(--accent); border-color: var(--accent); }

.btn-custom {
  padding: 8px 14px; border-radius: 8px;
  background: var(--surface2); border: 1px dashed var(--border);
  color: var(--text-dim); font-size: 0.78rem; font-weight: 700;
  cursor: pointer; transition: border-color .15s, color .15s;
}
.btn-custom:hover { border-color: var(--accent); color: var(--text); border-style: solid; }

/* ═══ Canvas action bar ═══════════ */
.canvas-action-bar {
  display: flex; align-items: center; flex-wrap: wrap;
  gap: 6px; margin-top: 8px;
  padding: 8px 10px;
  background: linear-gradient(180deg, rgba(13,17,30,0.55), rgba(13,17,30,0.85));
  border: 1px solid var(--border); border-radius: 10px;
  backdrop-filter: blur(3px);
}
.canvas-action-bar .btn { padding: 7px 14px; font-size: 0.78rem; min-height: 36px; }
.ab-sep { width: 1px; height: 22px; background: var(--border); margin: 0 3px; }
.ab-sep-push { margin-left: auto !important; background: transparent !important; }

.btn-calc {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 7px 14px; min-height: 36px;
  background: linear-gradient(180deg, #26c6da, #0097a7);
  color: #041c21; border: 1px solid rgba(255,255,255,0.15);
  border-radius: 8px; font-size: 0.78rem; font-weight: 700;
  box-shadow: 0 4px 12px rgba(38,198,218,0.3);
  cursor: pointer;
  transition: filter .15s, transform .15s, box-shadow .15s;
}
.btn-calc:hover  { filter: brightness(1.1); transform: translateY(-1px); box-shadow: 0 6px 16px rgba(38,198,218,0.45); }
.btn-calc:active { transform: translateY(0); }
.btn-calc:focus-visible { outline: 2px solid var(--gold); outline-offset: 2px; }

/* ═══ Calc modal ═══ */
.calc-modal {
  display: none; position: fixed; inset: 0; z-index: 1200;
  background: rgba(0,0,0,0.72); backdrop-filter: blur(4px);
  align-items: flex-start; justify-content: center;
  padding: 24px 16px; overflow-y: auto;
}
.calc-modal.active { display: flex; }
.calc-modal-box {
  background: #141a2e; border: 1px solid rgba(139,157,195,0.25); border-radius: 12px;
  width: 100%; max-width: 760px;
  display: flex; flex-direction: column;
  box-shadow: 0 24px 64px rgba(0,0,0,0.6);
  max-height: calc(100vh - 48px); overflow: hidden;
}
.calc-modal-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 14px 20px;
  border-bottom: 1px solid rgba(139,157,195,0.2);
  background: rgba(30,38,66,0.6); flex-shrink: 0;
}
.calc-modal-title { font-size: 1rem; font-weight: 800; color: #e1e7f3; }
.calc-modal-close {
  width: 34px; height: 34px;
  border: 1px solid rgba(139,157,195,0.3); border-radius: 8px;
  background: #0d1117; color: #8b9dc3;
  font-size: 1.4rem; line-height: 1; padding: 0;
  display: flex; align-items: center; justify-content: center; cursor: pointer;
  transition: border-color .15s, color .15s, background .15s;
}
.calc-modal-close:hover { border-color: var(--accent); color: #e1e7f3; background: #1a2340; }
.calc-modal-body { padding: 16px 20px; overflow-y: auto; display: flex; flex-direction: column; gap: 12px; }

.cs-inputs {
  background: rgba(38,198,218,0.08);
  border: 1px solid rgba(38,198,218,0.25); border-radius: 8px;
  padding: 12px 14px;
  display: flex; flex-direction: column; gap: 8px;
}
.cs-badge {
  display: inline-block; padding: 3px 12px; border-radius: 20px;
  background: rgba(38,198,218,0.22); color: var(--accent);
  font-size: 0.72rem; font-weight: 700;
  text-transform: uppercase; letter-spacing: .06em; align-self: flex-start;
}
.cs-given { display: flex; flex-wrap: wrap; gap: 6px 16px; }
.cs-given span { font-family: var(--mono); font-size: 0.82rem; color: #e1e7f3; }
.cs-si-note { font-size: 0.72rem; color: #8b9dc3; margin: 0; }

.cs-step {
  background: #0d1117;
  border: 1px solid rgba(139,157,195,0.18); border-radius: 8px;
  padding: 12px 14px;
  display: flex; flex-direction: column; gap: 6px;
}
.cs-step-hd { display: flex; align-items: baseline; gap: 8px; flex-wrap: wrap; }
.cs-num {
  font-size: 0.64rem; font-weight: 800;
  text-transform: uppercase; letter-spacing: .06em;
  color: var(--accent); background: var(--accent-lo);
  padding: 2px 8px; border-radius: 20px; white-space: nowrap;
}
.cs-title { font-size: 0.9rem; font-weight: 700; color: #e1e7f3; }
.cs-formula {
  font-family: var(--mono);
  font-size: 0.82rem; color: #b6c3e0;
  background: rgba(30,38,66,0.6); border-radius: 6px;
  padding: 6px 10px; border-left: 3px solid var(--accent);
}
.cs-calc   { font-family: var(--mono); font-size: 0.8rem; color: #e1e7f3; white-space: pre-wrap; line-height: 1.7; }
.cs-result { font-size: 0.88rem; color: #b6c3e0; margin-top: 2px; }
.cs-result strong { font-family: var(--mono); font-size: 0.95rem; color: var(--green); }

/* Custom-material fields */
.cm-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; margin-bottom: 10px; }
.cm-field { display: flex; flex-direction: column; gap: 4px; margin-bottom: 10px; font-size: 0.78rem; color: var(--text-dim); }
.cm-field input { padding: 8px 12px; border: 2px solid var(--border); border-radius: 8px; background: var(--bg); color: var(--text); font-family: var(--mono); font-size: 0.9rem; }
.cm-field input:focus { outline: none; border-color: var(--accent); }
.cm-field em { color: var(--accent); font-style: normal; font-family: var(--mono); }
.cm-hint { font-size: 0.74rem; color: var(--text-dim); margin-top: -4px; }
.cm-err  { font-size: 0.78rem; color: var(--red); font-weight: 600; }

/* ═══ Context menu ═════════════════════════════════════ */
.ctx-menu {
  position: fixed; z-index: 1300;
  background: #141a2e; border: 1px solid rgba(139,157,195,0.25); border-radius: 8px;
  box-shadow: 0 12px 32px rgba(0,0,0,0.55);
  padding: 4px; min-width: 180px;
}
.ctx-item {
  display: block; width: 100%; padding: 7px 12px;
  border: none; background: transparent; color: var(--text);
  font-size: 0.82rem; text-align: left; cursor: pointer; border-radius: 5px;
  transition: background .1s, color .1s;
}
.ctx-item:hover { background: var(--accent-lo); color: var(--accent); }
.ctx-sep { border-top: 1px solid var(--border); margin-top: 4px; padding-top: 9px; }

/* ═══ Learning Panels ═══════════════════ */
.learn-panels {
  padding: 14px;
  background: linear-gradient(180deg, rgba(30,38,66,0.6), rgba(20,26,46,0.6));
  border: 1px solid rgba(139,157,195,0.2);
  border-radius: 12px;
}
.learn-head {
  display: flex; align-items: center; justify-content: space-between;
  gap: 12px; flex-wrap: wrap;
  padding-bottom: 10px;
  border-bottom: 1px solid rgba(139,157,195,0.18);
  margin-bottom: 12px;
}
.learn-head-title { font-size: 0.95rem; font-weight: 700; color: #e1e7f3; }
.learn-head-actions { display: flex; gap: 8px; }
.learn-toggle-all {
  padding: 5px 12px;
  background: var(--accent-lo); border: 1px solid rgba(38,198,218,0.35);
  color: var(--accent); border-radius: 6px;
  font-size: 0.78rem; font-weight: 600; cursor: pointer;
  transition: background .15s, color .15s;
}
.learn-toggle-all:hover { background: rgba(38,198,218,.22); color: #e1e7f3; }
.learn-toggle-all:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.learn-card {
  border: 1px solid rgba(139,157,195,0.18); border-radius: 10px;
  background: rgba(13,17,30,0.55);
  margin-bottom: 10px; overflow: hidden;
  transition: border-color .2s;
}
.learn-card:last-child { margin-bottom: 0; }
.learn-card[open] { border-color: rgba(38,198,218,0.35); }
.learn-card > summary {
  list-style: none; cursor: pointer;
  padding: 10px 14px;
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  font-size: 0.88rem; font-weight: 700; color: #e1e7f3;
  user-select: none; transition: background .15s; position: relative;
}
.learn-card > summary::-webkit-details-marker { display: none; }
.learn-card > summary::marker { display: none; content: ''; }
.learn-card > summary:hover { background: rgba(38,198,218,0.08); }
.learn-card > summary::after {
  content: '\25BE'; margin-left: auto;
  color: #8b9dc3; font-size: 0.78rem;
  transition: transform .2s;
}
.learn-card[open] > summary::after { transform: rotate(180deg); color: var(--accent); }

.lp-badge {
  display: inline-flex; align-items: center; justify-content: center;
  width: 22px; height: 22px; border-radius: 6px;
  background: var(--accent-lo); font-size: 0.9rem; flex-shrink: 0; color: var(--accent);
}
.lp-sub { color: #8b9dc3; font-weight: 500; font-size: 0.78rem; }
.learn-body { padding: 12px 14px 14px; font-size: 0.84rem; color: var(--text-dim); line-height: 1.7; }
.learn-body .eq-line {
  font-family: var(--mono); font-size: 0.86rem; color: #e1e7f3;
  background: rgba(30,38,66,0.6); border-left: 3px solid var(--accent);
  padding: 6px 10px; border-radius: 6px; margin: 6px 0;
  white-space: pre-wrap;
}
.learn-body .eq-line b { color: var(--green); }
.learn-body .cmp-table { width: 100%; border-collapse: collapse; margin-top: 6px; font-size: 0.78rem; }
.learn-body .cmp-table th, .learn-body .cmp-table td { padding: 5px 8px; border-bottom: 1px solid rgba(139,157,195,0.12); text-align: right; }
.learn-body .cmp-table th { color: var(--accent); font-weight: 700; text-transform: uppercase; letter-spacing: .04em; font-size: 0.7rem; }
.learn-body .cmp-table td:first-child, .learn-body .cmp-table th:first-child { text-align: left; color: var(--text); }
.learn-body ul.coach-list { list-style: none; padding: 0; margin: 0; }
.learn-body ul.coach-list li { position: relative; padding: 5px 0 5px 22px; font-size: 0.84rem; color: var(--text-dim); line-height: 1.55; }
.learn-body ul.coach-list li::before { content: '\2022'; position: absolute; left: 6px; top: 5px; color: var(--accent); font-size: 1rem; }

/* User guide */
.user-guide { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px 20px; }
.user-guide-title { font-size: 1.05rem; font-weight: 800; color: var(--text); margin-bottom: 10px; display: flex; align-items: center; gap: 8px; }
.guide-icon-badge { display:inline-flex; align-items:center; justify-content:center; width:26px; height:26px; background:var(--accent-lo); border-radius:8px; font-size:1rem; }
.user-guide details { border-top: 1px solid var(--border); padding: 10px 0; }
.user-guide details:first-of-type { border-top: none; }
.user-guide summary { list-style: none; cursor: pointer; font-size: 0.92rem; font-weight: 700; color: var(--text); display: flex; align-items: center; gap: 10px; }
.user-guide summary::-webkit-details-marker { display: none; }
.user-guide summary::after { content: '\25BE'; margin-left: auto; color: var(--text-dim); transition: transform .2s; }
.user-guide details[open] summary::after { transform: rotate(180deg); color: var(--accent); }
.guide-section-num { display: inline-flex; align-items: center; justify-content: center; width: 22px; height: 22px; border-radius: 50%; background: var(--accent-lo); color: var(--accent); font-size: 0.76rem; font-weight: 800; }
.guide-content { padding: 10px 0 6px; color: var(--text-dim); font-size: 0.86rem; line-height: 1.7; }
.guide-content p { margin-bottom: 8px; }
.guide-content ul { padding-left: 20px; }
.guide-content ul li { margin-bottom: 6px; }
.guide-content a { color: var(--accent); text-decoration: none; }
.guide-content a:hover { text-decoration: underline; }

/* ═══ Responsive ═════════ */
@media (max-width: 768px) {
  .btn-calc { padding: 6px 10px; font-size: 0.74rem; }
  .canvas-toggles { max-width: 78%; }
  .canvas-action-bar .btn { padding: 6px 10px; font-size: 0.72rem; min-height: 32px; }
  .canvas-action-bar { padding: 6px 8px; gap: 4px; }
  .answer-grid { grid-template-columns: 1fr 1fr; }
  .is-grid { grid-template-columns: repeat(auto-fill, minmax(130px, 1fr)); }
  .controls-bar { gap: 10px; }
  .readout-row { grid-template-columns: repeat(2, 1fr); }
  .slider-row { grid-template-columns: 1fr; }
  .sim-select-group { min-width: 160px; }
  .cm-grid { grid-template-columns: 1fr; }
}
@media (max-width: 500px) {
  header h1 { font-size: 1.4rem; }
  .subtitle  { font-size: 0.78rem; }
  .btn-calc { padding: 6px 9px; font-size: 0.72rem; min-height: 32px; gap: 4px; }
  .btn-calc .btn-calc-label { display: none; }
  .ab-sep-push { display: none; }
  .canvas-toggles { top: 6px; left: 6px; padding: 4px 6px; max-width: 90%; }
  .cv-tog { font-size: 0.7rem; }
  .calc-modal { padding: 12px 8px; }
  .calc-modal-body { padding: 12px; }
  .cs-step { padding: 10px; }
  .learn-panels { padding: 10px; }
  .learn-card > summary { padding: 10px 12px; font-size: 0.82rem; }
  .lp-sub { display: none; }
  .learn-body { padding: 10px 12px 12px; }
  .learn-head-title { font-size: 0.85rem; }
  .learn-toggle-all { padding: 4px 10px; font-size: 0.72rem; }
  .preset-chip { padding: 4px 10px; font-size: 0.72rem; }
  .canvas-action-bar { padding: 6px; gap: 4px; }
  .ab-sep { display: none; }
  .seo-table { font-size: 0.74rem; }
  .seo-table th, .seo-table td { padding: 6px 7px; }
  .controls-bar { padding: 10px 12px; gap: 8px; }
  .pill { padding: 5px 10px; font-size: 0.76rem; }
  .answer-grid { grid-template-columns: 1fr; }
  .is-grid { grid-template-columns: 1fr 1fr; }
  .readout-row { grid-template-columns: 1fr 1fr; }
  .slider-row { grid-template-columns: 1fr; }
  .sim-select-group { min-width: 100%; }
}