/* ── Faraday's Law Simulator ─────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:        #0d1117;
  --surface:   #161b27;
  --surface2:  #1f2535;
  --border:    #2a3050;
  --accent:    #6366f1;
  --accent-lo: rgba(99,102,241,.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, #6366f1 0%, #a5b4fc 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 ─────────────────────────────────────────────── */
.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;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
}
.pill.active { background: var(--accent); color: #fff; box-shadow: 0 0 12px var(--accent-lo); }
.pill:hover:not(.active) { background: var(--surface2); color: var(--text); }

/* ── 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;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
}
.btn:disabled { opacity: 0.38; cursor: not-allowed; }
.btn-primary { background: var(--accent); color: #fff; }
.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); }

/* ── 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: grab; touch-action: pan-y; }
.canvas-card canvas.grabbing { cursor: grabbing; }

/* ── 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; }
.motion-row { gap: 10px; }
.motion-hint { font-size: 0.78rem; color: var(--text-dim); font-style: italic; }
.sim-slider-group { display: flex; align-items: center; gap: 10px; flex: 1 1 460px; min-width: 320px; }
.sim-slider-group .sim-slider { min-width: 110px; }
.sim-slider-label { font-size: 0.76rem; font-weight: 700; color: var(--text-dim); white-space: nowrap; min-width: 110px; }
.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: -7px;
  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;
}
.graph-toggle-group .pill-tabs { padding: 2px; }
.graph-toggle-group .pill { padding: 4px 10px; font-size: 0.76rem; }

.readout-row {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(120px, 1fr)); gap: 8px;
}
.readout-card {
  background: var(--bg); border: 1px solid var(--border); border-radius: 8px;
  padding: 8px 12px; text-align: center; transition: box-shadow .25s, border-color .25s;
}
.readout-card.flash { border-color: var(--accent); box-shadow: 0 0 0 1px var(--accent), 0 0 14px var(--accent-lo); }
.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-unit { font-size: 0.68rem; color: var(--text-dim); margin-left: 2px; }

/* ── Readout colour overrides ──────────────────────────────── */
.readout-card.pos  .readout-val { color: #a5b4fc; }
.readout-card.vel  .readout-val { color: #4fc3f7; }
.readout-card.flux .readout-val { color: #ffb74d; }
.readout-card.dphi .readout-val { color: #ce93d8; }
.readout-card.emf  .readout-val { color: #3ddc84; }
.readout-card.cur  .readout-val { color: #f5c842; }

/* ── Lenz / status strip ───────────────────────────────────── */
.status-strip { display: flex; flex-wrap: wrap; gap: 8px; }
.status-chip {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 7px 13px; border-radius: 22px;
  background: var(--bg); border: 1px solid var(--border);
  font-size: 0.8rem; font-weight: 600; color: var(--text);
}
.status-chip .sc-dot {
  width: 10px; height: 10px; border-radius: 50%; flex: none;
  background: var(--text-dim); box-shadow: 0 0 6px transparent; transition: background .2s, box-shadow .2s;
}
.status-chip.up    .sc-dot { background: var(--green); box-shadow: 0 0 8px rgba(61,220,132,.7); }
.status-chip.down  .sc-dot { background: var(--red);   box-shadow: 0 0 8px rgba(255,85,85,.7); }
.status-chip.cw    .sc-dot { background: var(--gold);  box-shadow: 0 0 8px rgba(245,200,66,.7); }
.status-chip.ccw   .sc-dot { background: #4fc3f7;      box-shadow: 0 0 8px rgba(79,195,247,.7); }
.status-chip.npole .sc-dot { background: #42a5f5; }
.status-chip.spole .sc-dot { background: #ef5350; }

/* ── 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(99,102,241,.45); color: var(--text); }
.is-btn.active { border-color: var(--accent); color: #fff; background: rgba(99,102,241,.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(99,102,241,.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-input-row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin-bottom: 10px; }
.qi-input {
  flex: 1; min-width: 120px; max-width: 200px;
  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;
}
.qi-input:focus { outline: none; border-color: var(--accent); }
.qi-unit { font-size: 0.84rem; color: var(--text-dim); font-weight: 600; }

.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 */
.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; font-weight: 700; color: var(--text); margin-bottom: 12px; }
.seo-article h3 { font-size: 1rem; font-weight: 700; color: var(--accent); margin: 16px 0 8px; }
.seo-article p { font-size: 0.88rem; color: var(--text-dim); margin-bottom: 10px; }
.seo-article strong { color: var(--text); }

/* ── Featured-snippet table ────────────────────────────────── */
.feature-table {
  width: 100%; border-collapse: collapse; margin: 10px 0 14px;
  font-size: 0.82rem;
}
.feature-table th, .feature-table td {
  padding: 8px 10px; text-align: left;
  border-bottom: 1px solid var(--border);
}
.feature-table th {
  background: var(--surface2); color: var(--accent);
  font-weight: 700; font-size: 0.74rem; text-transform: uppercase; letter-spacing: 0.05em;
}
.feature-table td { color: var(--text-dim); }
.feature-table td:first-child { color: var(--text); font-weight: 600; }

/* ── Responsive ────────────────────────────────────────────── */
@media (max-width: 768px) {
  .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(3, 1fr); }
  .sim-slider-group { min-width: 160px; }
}
@media (max-width: 500px) {
  header h1 { font-size: 1.4rem; }
  .subtitle  { font-size: 0.78rem; }
  .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; }
  .sim-slider-group { min-width: 100%; }
  .status-chip { font-size: 0.74rem; padding: 6px 10px; }
}

/* ── Stepper inputs (companion to sliders) ─────────────────── */
.stepper {
  display: inline-flex; align-items: center; gap: 4px;
  background: var(--bg); border: 1px solid var(--border); border-radius: 8px;
  padding: 2px; min-width: 130px;
}
.step-btn {
  width: 26px; height: 26px; border: none; border-radius: 6px;
  background: var(--surface2); color: var(--accent);
  cursor: pointer; font-size: 1rem; font-weight: 700;
  display: flex; align-items: center; justify-content: center;
  transition: background .15s, color .15s;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
}
.step-btn:hover { background: var(--accent); color: #fff; }
.step-input {
  flex: 1; width: 60px; min-width: 50px;
  border: none; background: transparent; color: var(--accent);
  font-family: var(--mono); font-weight: 700; font-size: 0.85rem;
  text-align: center; padding: 4px 2px;
  -moz-appearance: textfield;
}
.step-input::-webkit-outer-spin-button,
.step-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.step-input:focus { outline: 1px solid var(--accent); border-radius: 4px; }

/* ── Presets row ──────────────────────────────────────────── */
.preset-row {
  display: flex; flex-wrap: wrap; gap: 8px; align-items: center;
  padding-bottom: 10px; border-bottom: 1px solid var(--border);
}
.preset-btn {
  padding: 6px 12px; border-radius: 18px;
  background: var(--surface2); border: 1px solid var(--border);
  color: var(--text); font-size: 0.76rem; font-weight: 600; cursor: pointer;
  transition: border-color .15s, background .15s, color .15s;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
}
.preset-btn:hover { border-color: var(--accent); color: var(--accent); }
.preset-btn.active { background: var(--accent); color: #fff; border-color: var(--accent); }

/* ── Calc FAB + Calculation Modal ─────────────────────────── */
.btn-calc-fab {
  position: absolute; right: 12px; bottom: 12px; z-index: 3;
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 16px;
  background: linear-gradient(180deg, #818cf8, #6366f1);
  color: #fff; border: 1px solid rgba(255,255,255,0.15);
  border-radius: 10px; font-size: 0.84rem; font-weight: 700;
  box-shadow: 0 6px 18px var(--accent-lo);
  cursor: pointer;
  transition: filter .15s, transform .15s, box-shadow .15s;
  touch-action: manipulation;
}
.btn-calc-fab:hover  { filter: brightness(1.1); transform: translateY(-1px); }
.btn-calc-fab:active { transform: translateY(0); }
.btn-calc-fab:focus-visible { outline: 2px solid var(--gold); outline-offset: 2px; }

.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: var(--surface); border: 1px solid var(--border); 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 var(--border);
  background: var(--surface2);
}
.calc-modal-title { font-size: 1rem; font-weight: 800; color: var(--text); }
.calc-modal-close {
  width: 34px; height: 34px;
  border: 1px solid var(--border); border-radius: 8px;
  background: var(--bg); color: var(--text-dim);
  font-size: 1.4rem; line-height: 1; padding: 0; cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: border-color .15s, color .15s, background .15s;
}
.calc-modal-close:hover { border-color: var(--accent); color: var(--text); background: var(--surface2); }
.calc-modal-body { padding: 16px 20px; overflow-y: auto; display: flex; flex-direction: column; gap: 12px; }

.cs-inputs {
  background: var(--accent-lo);
  border: 1px solid var(--accent); 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: var(--accent); color: #fff;
  font-size: 0.7rem; font-weight: 700;
  text-transform: uppercase; letter-spacing: 0.06em; 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: var(--text); }
.cs-step {
  background: var(--bg);
  border: 1px solid var(--border); 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: 0.06em;
  color: #fff; background: var(--accent);
  padding: 2px 8px; border-radius: 20px;
}
.cs-title { font-size: 0.9rem; font-weight: 700; color: var(--text); }
.cs-formula {
  font-family: var(--mono); font-size: 0.82rem; color: var(--text-dim);
  background: var(--surface2); border-radius: 6px;
  padding: 6px 10px; border-left: 3px solid var(--accent);
}
.cs-calc   { font-family: var(--mono); font-size: 0.8rem; color: var(--text); white-space: pre-wrap; line-height: 1.7; }
.cs-result { font-size: 0.88rem; color: var(--text-dim); }
.cs-result strong { font-family: var(--mono); font-size: 0.95rem; color: var(--green); }

/* ── Learning Panels (collapsible) ────────────────────────── */
.learn-panels {
  margin-top: 6px; padding: 14px;
  background: var(--surface2);
  border: 1px solid var(--border);
  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 var(--border);
  margin-bottom: 12px;
}
.learn-head-title { font-size: 0.95rem; font-weight: 700; color: var(--text); }
.learn-head-actions { display: flex; gap: 8px; }
.learn-toggle-all {
  padding: 5px 12px;
  background: var(--accent-lo); border: 1px solid var(--accent);
  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: var(--accent); color: #fff; }

.learn-card {
  border: 1px solid var(--border); border-radius: 10px;
  background: var(--bg);
  margin-bottom: 10px; overflow: hidden;
}
.learn-card:last-child { margin-bottom: 0; }
.learn-card[open] { border-color: var(--accent); }
.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: var(--text);
  user-select: none; transition: background .15s;
}
.learn-card > summary::-webkit-details-marker { display: none; }
.learn-card > summary::marker { content: ''; }
.learn-card > summary:hover { background: var(--accent-lo); }
.learn-card > summary::after {
  content: '\25BE'; margin-left: auto;
  color: var(--text-dim); 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;
}
.lp-sub { color: var(--text-dim); font-weight: 500; font-size: 0.78rem; }
.learn-body { padding: 12px 14px 14px; }

.live-eq { display: flex; flex-direction: column; gap: 8px; }
.live-eq .leq {
  font-family: var(--mono); font-size: 0.84rem; color: var(--text);
  background: var(--surface2); border-left: 3px solid var(--accent);
  padding: 8px 12px; border-radius: 6px; line-height: 1.6;
}
.live-eq .leq strong { color: var(--green); }
.live-eq .leq-label { color: var(--text-dim); font-size: 0.78rem; }

.coach-list { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 6px; }
.coach-list li {
  font-size: 0.82rem; color: var(--text-dim); line-height: 1.55;
  padding: 8px 12px;
  background: var(--surface2); border-radius: 6px;
  border-left: 3px solid var(--gold);
}
.coach-list li strong { color: var(--text); }

/* ── Right-click context menu ─────────────────────────────── */
.ctx-menu {
  display: none; position: fixed; z-index: 1500;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 8px; padding: 4px; min-width: 160px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.5);
}
.ctx-menu.active { display: block; }
.ctx-menu button {
  display: block; width: 100%; padding: 8px 12px;
  background: none; border: none; color: var(--text);
  font-size: 0.82rem; text-align: left; cursor: pointer; border-radius: 4px;
}
.ctx-menu button:hover { background: var(--accent-lo); color: var(--accent); }

@media (max-width: 768px) {
  .btn-calc-fab { padding: 8px 12px; font-size: 0.78rem; }
}
@media (max-width: 500px) {
  .btn-calc-fab { right: 6px; bottom: 6px; padding: 7px 9px; font-size: 0.72rem; gap: 4px; }
  .btn-calc-fab .btn-calc-label { display: none; }
  .calc-modal { padding: 12px 8px; }
  .calc-modal-body { padding: 12px; }
  .cs-step { padding: 10px; }
  .learn-panels { padding: 10px; }
  .lp-sub { display: none; }
  .stepper { min-width: 110px; }
  .step-input { width: 44px; }
  .preset-btn { font-size: 0.7rem; padding: 5px 9px; }
  .feature-table { font-size: 0.76rem; }
  .feature-table th, .feature-table td { padding: 6px 7px; }
}

/* INTERLINK-START  header quick-links */
.head-actions{display:flex;align-items:center;gap:8px;margin-left:auto;flex-wrap:wrap;justify-content:flex-end;}
.btn-link{display:inline-flex;align-items:center;gap:7px;padding:5px 12px;border-radius:8px;font-size:.82rem;font-weight:700;text-decoration:none;cursor:pointer;background:var(--surface2,#1f2535);color:var(--text,#dde3f0);border:1.5px solid var(--border,#2a3050);white-space:nowrap;transition:border-color .18s,background .18s,color .18s;}
.btn-link:hover{border-color:var(--accent,#6366f1);background:var(--accent-lo,rgba(99,102,241,.18));color:#fff;}
.btn-link img{width:20px;height:20px;border-radius:4px;flex:none;}
.btn-link .lbl{line-height:1;}
@media(max-width:560px){.btn-link .lbl{display:none;}.btn-link{padding:5px 9px;}}
/* INTERLINK-END */