/* ── Reset & Tokens ─────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --bg: #0d1117; --surface: #161b27; --surface2: #1f2535; --border: #2a3050;
  --accent: #ff6e40; --accent-lo: rgba(255,110,64,.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; padding-bottom: 40px; }

/* ── Header ─────────────────────────────────────────────────── */
header { text-align: center; padding: 4px 0; }
header h1 {
  font-size: 1.8rem; font-weight: 700;
  background: linear-gradient(120deg, var(--accent) 0%, #ffb199 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; flex-wrap: wrap; }
.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; flex-wrap: wrap; }
.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: #1a1a2e; box-shadow: 0 0 12px var(--accent-lo); font-weight: 700; }
.pill:hover:not(.active) { background: var(--surface2); color: var(--text); }

/* ── Geometry tabs ──────────────────────────────────────────── */
.geo-tabs { display: flex; flex-wrap: wrap; gap: 6px; }
.geo-btn {
  padding: 6px 12px; border: 1px solid var(--border); background: var(--surface2);
  color: var(--text-dim); border-radius: 6px; cursor: pointer; font-size: 0.79rem;
  transition: all .18s;
}
.geo-btn.active { background: var(--accent); color: #1a1a2e; border-color: var(--accent); box-shadow: 0 0 10px var(--accent-lo); font-weight: 700; }
.geo-btn:hover:not(.active) { background: var(--border); color: var(--text); }

/* ── Material info badge ────────────────────────────────────── */
.mat-info { color: var(--text-dim); font-size: 0.78rem; font-family: var(--mono); margin-left: 6px; }
.mat-info b { color: var(--accent); }

/* ── 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: #1a1a2e; }
.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 {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 10px;
  overflow-x: clip; position: relative;
}
.canvas-card canvas { display: block; width: 100%; height: auto; touch-action: pan-y; }

/* ── Sim layout ─────────────────────────────────────────────── */
.sim-layout { display: grid; grid-template-columns: 1fr 250px; gap: 14px; align-items: start; }
.canvas-col { display: flex; flex-direction: column; gap: 10px; min-width: 0; }
.canvas-controls {
  /* Tighter action-bar variant that sits directly under the canvas */
  padding: 10px 14px; gap: 10px;
}
.canvas-controls .cycle-readout { margin-left: auto; }
.sim-controls {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 14px;
  display: flex; flex-direction: column; gap: 14px;
}
.slider-group { display: flex; flex-direction: column; gap: 5px; }
.slider-group label {
  font-size: 0.75rem; color: var(--text-dim); text-transform: uppercase;
  letter-spacing: .04em; display: flex; justify-content: space-between; align-items: center;
}
.slider-group label .val-span { color: var(--accent); font-weight: 700; font-family: var(--mono); cursor: pointer; }
.slider-group label .val-span:hover { text-decoration: underline; }

/* Slider — gradient track for visibility */
.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); width: 100%;
}
.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));
  border: none;
}
.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;
}

/* Stepper-style numeric input */
.slider-row { display: flex; align-items: center; gap: 6px; margin-top: 2px; }
.slider-row .sim-slider { flex: 1; min-width: 0; }
.step-btn {
  width: 28px; height: 28px; border: 1px solid var(--border);
  background: var(--surface2); color: var(--text);
  border-radius: 6px; cursor: pointer; font-size: 1rem; line-height: 1;
  font-weight: 700;
}
.step-btn:hover { background: var(--border); color: var(--accent); }
.step-input {
  width: 70px; padding: 5px 6px; border: 1px solid var(--border);
  background: var(--bg); color: var(--accent);
  border-radius: 6px; font-family: var(--mono); font-size: 0.85rem; text-align: center;
  font-weight: 700;
}
.step-input:focus { border-color: var(--accent); outline: none; box-shadow: 0 0 6px var(--accent-lo); }
.step-unit { font-size: 0.72rem; color: var(--text-dim); min-width: 38px; }

/* ── Readout panel ──────────────────────────────────────────── */
.readout-panel {
  display: flex; align-items: center; gap: 16px; flex-wrap: wrap;
  padding: 14px 18px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
}
.readout-big { display: flex; flex-direction: column; align-items: center; min-width: 120px; }
.readout-big .readout-label { font-size: 0.72rem; text-transform: uppercase; color: var(--text-dim); letter-spacing: .06em; }
.readout-big .readout-value { font-size: 2rem; font-weight: 700; color: var(--accent); font-family: var(--mono); }
.readout-cells { display: flex; gap: 10px; flex-wrap: wrap; flex: 1; }
.readout-cell {
  background: var(--surface2); border: 1px solid var(--border);
  border-radius: 8px; padding: 10px 14px; display: flex; flex-direction: column; gap: 2px;
  min-width: 110px; flex: 1;
}
.readout-cell .readout-label { font-size: 0.68rem; text-transform: uppercase; color: var(--text-dim); letter-spacing: .04em; }
.readout-cell .readout-val { font-size: 0.95rem; font-weight: 700; color: var(--text); font-family: var(--mono); }
.readout-cell.status-safe .readout-val { color: var(--green); }
.readout-cell.status-warn .readout-val { color: var(--gold); }
.readout-cell.status-fail .readout-val { color: var(--red); text-shadow: 0 0 8px rgba(255,85,85,.4); }

/* ── Readout badges ─────────────────────────────────────────── */
.readout-badges {
  display: flex; gap: 8px; flex-wrap: wrap;
  padding: 8px 12px;
  background: var(--surface); border: 1px solid var(--border); border-radius: 10px;
}
.readout-badge {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 4px 10px; background: var(--surface2); border-radius: 8px;
  font-size: 0.78rem; color: var(--text-dim);
}
.readout-badge strong { color: var(--text); font-family: var(--mono); margin: 0 2px; }
.rb-dot { width: 8px; height: 8px; border-radius: 50%; display: inline-block; }

/* ── Scenario picker ────────────────────────────────────────── */
.scenario-bar #scenario-select { min-width: 320px; flex: 1; }
.scenario-desc {
  padding: 12px 16px;
  background: linear-gradient(90deg, rgba(255,110,64,.10), rgba(255,110,64,.02));
  border: 1px solid rgba(255,110,64,.35);
  border-left: 4px solid var(--accent);
  border-radius: 10px;
  font-size: 0.87rem; color: var(--text); line-height: 1.55;
}
.scenario-desc .sc-name { font-weight: 700; color: var(--accent); font-size: 0.95rem; display: block; margin-bottom: 4px; }
.scenario-desc .sc-expect { display: block; margin-top: 6px; color: var(--text-dim); font-style: italic; font-size: 0.82rem; }
.scenario-desc .sc-expect b { color: var(--gold); font-style: normal; }

/* ── Fracture banner (when a >= a_c) ───────────────────────── */
.fracture-banner {
  padding: 14px 18px; border-radius: 10px;
  background: linear-gradient(90deg, rgba(255,85,85,.25), rgba(255,85,85,.08));
  border: 2px solid var(--red);
  color: #fff; font-weight: 700; font-size: 0.95rem;
  display: flex; align-items: center; gap: 12px;
  box-shadow: 0 0 24px rgba(255,85,85,0.4);
  animation: pulseRed 1.2s ease-in-out infinite;
}
.fracture-banner .fb-icon { font-size: 1.6rem; }
.fracture-banner .fb-text { flex: 1; }
.fracture-banner .fb-text small { display: block; font-weight: 400; color: rgba(255,255,255,0.85); font-size: 0.78rem; margin-top: 2px; }
@keyframes pulseRed { 0%, 100% { box-shadow: 0 0 24px rgba(255,85,85,0.4); } 50% { box-shadow: 0 0 36px rgba(255,85,85,0.7); } }

.safe-banner {
  padding: 12px 18px; border-radius: 10px;
  background: linear-gradient(90deg, rgba(61,220,132,.18), rgba(61,220,132,.04));
  border: 2px solid var(--green); color: var(--text);
  font-weight: 700; font-size: 0.92rem;
  display: flex; align-items: center; gap: 10px;
}
.safe-banner .fb-icon { font-size: 1.4rem; }

.warn-banner {
  padding: 12px 18px; border-radius: 10px;
  background: linear-gradient(90deg, rgba(245,200,66,.18), rgba(245,200,66,.04));
  border: 2px solid var(--gold); color: var(--text);
  font-weight: 700; font-size: 0.92rem;
  display: flex; align-items: center; gap: 10px;
}

/* ── Mode sections ──────────────────────────────────────────── */
.mode-section { display: flex; flex-direction: column; gap: 14px; }

/* ── Explore cards ──────────────────────────────────────────── */
.explore-cards { display: flex; flex-direction: column; gap: 12px; }
.concept-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px 20px;
  border-left: 4px solid var(--accent);
}
.concept-card h3 { font-size: 1.05rem; color: var(--accent); margin-bottom: 10px; }
.concept-card .formula { font-family: var(--mono); color: var(--gold); font-size: 0.94rem; margin: 8px 0; padding: 10px 14px; background: var(--surface2); border-radius: 6px; }
.concept-card p { font-size: 0.9rem; color: var(--text); line-height: 1.6; margin-bottom: 8px; }
.concept-card .example { margin-top: 10px; padding: 12px 14px; background: var(--bg); border: 1px solid var(--border); border-radius: 8px; font-size: 0.85rem; color: var(--text-dim); line-height: 1.55; }
.concept-card .example strong { color: var(--green); }
.concept-card ul { margin: 8px 0 8px 20px; font-size: 0.88rem; line-height: 1.6; color: var(--text); }
.concept-card .mat-table { width: 100%; border-collapse: collapse; margin-top: 8px; font-size: 0.82rem; }
.concept-card .mat-table th, .concept-card .mat-table td { padding: 6px 10px; border-bottom: 1px solid var(--border); text-align: left; }
.concept-card .mat-table th { color: var(--accent); font-weight: 700; }
.concept-card .mat-table td { color: var(--text); font-family: var(--mono); }

/* ── Practice ───────────────────────────────────────────────── */
.practice-bar {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
  padding: 14px 16px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
}
.practice-prompt { font-size: 0.9rem; color: var(--text); flex: 1 1 100%; line-height: 1.55; }
.practice-prompt b { color: var(--accent); }
.practice-input-group { display: flex; align-items: center; gap: 6px; }
.practice-input {
  width: 130px; padding: 7px 10px; border: 1px solid var(--border); border-radius: 6px;
  background: var(--bg); color: var(--text); font-size: 0.92rem; font-family: var(--mono);
}
.practice-input:focus { border-color: var(--accent); outline: none; box-shadow: 0 0 8px var(--accent-lo); }
.practice-unit { font-size: 0.82rem; color: var(--text-dim); }
.pbar-score { font-size: 0.84rem; color: var(--text-dim); margin-left: auto; }
.pbar-score span { color: var(--text); font-weight: 700; }
.practice-feedback { font-size: 0.88rem; font-weight: 600; min-height: 24px; }
.feedback-ok { color: var(--green); }
.feedback-err { color: var(--red); }
.practice-solution {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 16px 18px;
  font-size: 0.88rem; line-height: 1.65; color: var(--text);
}
.practice-solution b { color: var(--accent); display: inline-block; margin-top: 6px; }
.practice-solution .step-eq { font-family: var(--mono); background: var(--bg); padding: 4px 8px; border-radius: 4px; color: var(--gold); }

/* ── Quiz ───────────────────────────────────────────────────── */
.quiz-bar {
  display: flex; flex-direction: column; gap: 12px;
  padding: 16px 18px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
}
.quiz-counter { font-size: 0.78rem; text-transform: uppercase; color: var(--text-dim); letter-spacing: .06em; }
.quiz-prompt { font-size: 0.94rem; color: var(--text); line-height: 1.55; }
.quiz-prompt b { color: var(--accent); }
.quiz-options { display: flex; flex-direction: column; gap: 8px; }
.quiz-opt {
  padding: 10px 14px; background: var(--surface2); border: 1px solid var(--border);
  border-radius: 8px; cursor: pointer; font-size: 0.88rem; color: var(--text);
  transition: all .15s;
}
.quiz-opt:hover { border-color: var(--accent); background: var(--bg); }
.quiz-opt.selected { border-color: var(--accent); background: var(--accent-lo); }
.quiz-opt.correct { border-color: var(--green); background: rgba(61,220,132,.15); }
.quiz-opt.wrong { border-color: var(--red); background: rgba(255,85,85,.15); }
.quiz-actions { display: flex; gap: 10px; }
.quiz-input-group { display: flex; align-items: center; gap: 6px; }

/* ── Quiz result ────────────────────────────────────────────── */
.quiz-result {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 22px 24px;
  display: flex; flex-direction: column; gap: 14px;
}
.qr-header { text-align: center; }
.qr-score { font-size: 2rem; font-weight: 700; }
.qr-score.perfect { color: var(--gold); }
.qr-score.good { color: var(--green); }
.qr-score.poor { color: var(--red); }
.qr-stars { font-size: 1.6rem; margin-top: 4px; }
.qr-rows { display: flex; flex-direction: column; gap: 8px; }
.qr-row {
  padding: 10px 14px; border-radius: 8px; font-size: 0.86rem;
  background: var(--surface2); border-left: 3px solid var(--border);
}
.qr-row.ok { border-left-color: var(--green); }
.qr-row.err { border-left-color: var(--red); }
.qr-row .qr-q { color: var(--text-dim); margin-bottom: 4px; }
.qr-row .qr-a { color: var(--text); }

/* ── SEO article ────────────────────────────────────────────── */
.seo-article {
  margin-top: 32px; padding: 28px 22px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  line-height: 1.7; color: var(--text-dim);
}
.seo-article h2 { font-size: 1.3rem; color: var(--text); margin-bottom: 14px; }
.seo-article h3 { font-size: 1.05rem; color: var(--text); margin: 18px 0 8px; }
.seo-article p { margin-bottom: 12px; font-size: 0.92rem; }
.seo-article a { color: var(--accent); text-decoration: none; }
.seo-article a:hover { text-decoration: underline; }

/* ── Hint bar ───────────────────────────────────────────────── */
.hint-bar {
  display: flex; align-items: center; gap: 10px;
  padding: 8px 14px; border-radius: 10px;
  background: linear-gradient(90deg, rgba(255,110,64,.12), rgba(255,110,64,.04));
  border: 1px solid rgba(255,110,64,.35); color: var(--text);
  font-size: 0.82rem; line-height: 1.45;
}
.hint-icon { font-size: 1rem; }
.hint-close {
  margin-left: auto; background: transparent; border: none;
  color: var(--text-dim); font-size: 1.1rem; cursor: pointer; padding: 0 6px;
}
.hint-close:hover { color: var(--text); }

/* ── Action bar ─────────────────────────────────────────────── */
.action-bar {
  display: flex; flex-wrap: wrap; align-items: center; gap: 10px;
  padding: 10px 14px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
}
.preset-select {
  padding: 6px 10px; background: var(--bg); color: var(--text);
  border: 1px solid var(--border); border-radius: 6px; font-size: 0.84rem;
  cursor: pointer; min-width: 220px;
}
.preset-select:focus { border-color: var(--accent); outline: none; box-shadow: 0 0 8px var(--accent-lo); }
.toggle-chip {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 6px 12px; background: var(--surface2); border: 1px solid var(--border);
  border-radius: 6px; font-size: 0.8rem; color: var(--text); cursor: pointer;
}
.toggle-chip input { accent-color: var(--accent); cursor: pointer; }

.cycle-readout { font-size: 0.82rem; color: var(--text-dim); margin-left: auto; }
.cycle-readout strong { color: var(--accent); font-family: var(--mono); }

/* ── Learning panels ────────────────────────────────────────── */
.learn-panels {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 12px 14px; display: flex; flex-direction: column; gap: 10px;
}
.learn-head { display: flex; align-items: center; justify-content: space-between; gap: 10px; flex-wrap: wrap; }
.learn-head-title { font-size: 0.95rem; color: var(--text); font-weight: 700; }
.learn-head-actions { display: flex; gap: 6px; }
.learn-toggle-all {
  padding: 4px 10px; background: var(--surface2); border: 1px solid var(--border);
  color: var(--text-dim); border-radius: 6px; font-size: 0.74rem; cursor: pointer;
}
.learn-toggle-all:hover { background: var(--border); color: var(--text); }
.learn-card {
  background: var(--surface2); border: 1px solid var(--border); border-radius: 8px;
  padding: 10px 14px;
}
.learn-card summary {
  cursor: pointer; font-size: 0.88rem; color: var(--text); list-style: none;
  display: flex; align-items: center; gap: 8px;
}
.learn-card summary::-webkit-details-marker { display: none; }
.lp-badge {
  width: 22px; height: 22px; border-radius: 50%;
  background: var(--accent-lo); color: var(--accent);
  display: inline-flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 0.78rem;
}
.lp-sub { color: var(--text-dim); font-weight: 400; font-size: 0.78rem; }
.learn-body { padding-top: 10px; font-size: 0.86rem; line-height: 1.55; color: var(--text); }
.learn-body p { margin-bottom: 6px; }
.learn-body canvas { display: block; width: 100%; height: auto; background: var(--bg); border-radius: 6px; }
.lp-note { color: var(--text-dim); font-size: 0.76rem; margin-top: 6px; }
.lp-eq-line { margin: 6px 0; padding: 8px 10px; background: var(--bg); border-radius: 6px; font-size: 0.95rem; overflow-x: auto; }
.coach-item { padding: 8px 0; border-bottom: 1px dashed var(--border); }
.coach-item:last-child { border-bottom: none; }
.coach-item .coach-tag {
  display: inline-block; font-size: 0.7rem; padding: 2px 8px; border-radius: 4px;
  background: var(--accent-lo); color: var(--accent); margin-right: 6px; font-weight: 700;
}
.coach-item .coach-tag.warn { background: rgba(245,200,66,.2); color: var(--gold); }
.coach-item .coach-tag.danger { background: rgba(255,85,85,.2); color: var(--red); }

/* ── Modal ─────────────────────────────────────────────────── */
.modal-backdrop {
  position: fixed; inset: 0; background: rgba(0,0,0,.6); z-index: 9000;
  display: flex; align-items: center; justify-content: center; padding: 20px;
}
.modal-card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  max-width: 600px; width: 100%; max-height: 88vh; overflow: hidden;
  display: flex; flex-direction: column;
}
.modal-head {
  padding: 14px 18px; display: flex; align-items: center; justify-content: space-between;
  border-bottom: 1px solid var(--border);
}
.modal-head h3 { font-size: 1rem; color: var(--accent); }
.modal-close {
  background: transparent; border: none; color: var(--text-dim);
  font-size: 1.4rem; cursor: pointer; padding: 0 8px;
}
.modal-close:hover { color: var(--text); }
.modal-body {
  padding: 16px 20px; overflow-y: auto; line-height: 1.65;
  font-size: 0.9rem; color: var(--text);
}
.modal-body .calc-step { margin-bottom: 14px; }
.modal-body .calc-step b { color: var(--accent); display: block; margin-bottom: 4px; font-size: 0.82rem; }
.modal-body .calc-eq { font-family: var(--mono); background: var(--bg); padding: 6px 10px; border-radius: 6px; display: inline-block; color: var(--gold); }

/* ── Context menu ──────────────────────────────────────────── */
.ctx-menu {
  position: fixed; z-index: 9500; list-style: none;
  background: var(--surface); border: 1px solid var(--border); border-radius: 8px;
  box-shadow: 0 6px 20px rgba(0,0,0,.5); padding: 4px 0; min-width: 170px;
}
.ctx-menu li {
  padding: 6px 14px; font-size: 0.84rem; color: var(--text); cursor: pointer;
}
.ctx-menu li:hover { background: var(--surface2); color: var(--accent); }
.ctx-menu li.sep { padding: 2px 0; border-top: 1px solid var(--border); cursor: default; }
.ctx-menu li.sep:hover { background: transparent; }

/* ── Snippet table ─────────────────────────────────────────── */
.snippet-table {
  width: 100%; border-collapse: collapse; margin: 10px 0 18px;
  font-size: 0.86rem; background: var(--surface2);
  border: 1px solid var(--border); border-radius: 8px; overflow: hidden;
}
.snippet-table th, .snippet-table td {
  padding: 8px 12px; text-align: left; border-bottom: 1px solid var(--border);
}
.snippet-table th { background: var(--bg); color: var(--accent); font-size: 0.78rem; text-transform: uppercase; letter-spacing: .05em; }
.snippet-table tr:last-child td { border-bottom: none; }
.snippet-table td { color: var(--text); }

/* ── User guide ─────────────────────────────────────────────── */
.user-guide {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px 22px; margin-top: 18px;
  display: flex; flex-direction: column; gap: 6px;
}
.user-guide-title {
  font-size: 1rem; font-weight: 700; color: var(--text);
  padding-bottom: 8px; border-bottom: 1px solid var(--border);
  display: flex; align-items: center; gap: 8px; margin-bottom: 6px;
}
.guide-icon-badge { font-size: 1.1rem; }
.user-guide details { padding: 6px 0; border-bottom: 1px dashed var(--border); }
.user-guide details:last-child { border-bottom: none; }
.user-guide summary { cursor: pointer; padding: 8px 4px; font-size: 0.92rem; color: var(--text); display: flex; align-items: center; gap: 8px; list-style: none; }
.user-guide summary::-webkit-details-marker { display: none; }
.user-guide summary::before { content: "\25B8"; color: var(--accent); transition: transform .15s; display: inline-block; }
.user-guide details[open] > summary::before { transform: rotate(90deg); }
.guide-section-num {
  display: inline-flex; width: 24px; height: 24px; border-radius: 50%;
  background: var(--accent-lo); color: var(--accent); align-items: center; justify-content: center;
  font-size: 0.78rem; font-weight: 700; font-family: var(--mono);
}
.guide-content { padding: 4px 6px 8px 36px; font-size: 0.88rem; line-height: 1.6; color: var(--text-dim); }
.guide-content strong { color: var(--text); }
.guide-content ul { margin-left: 18px; margin-top: 4px; }
.guide-content li { margin-bottom: 4px; }

/* ── Responsive ─────────────────────────────────────────────── */
@media (max-width: 768px) {
  .sim-layout { grid-template-columns: 1fr; }
  .readout-panel { flex-direction: column; align-items: stretch; }
  .readout-big { flex-direction: row; gap: 10px; justify-content: center; }
  .controls-bar { gap: 10px; }
  .geo-tabs { gap: 4px; }
  .preset-select { min-width: 100%; }
}

@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; }
  .geo-btn { padding: 4px 8px; font-size: 0.72rem; }
  .readout-cells { flex-direction: column; }
  .readout-big .readout-value { font-size: 1.6rem; }
  .seo-article { padding: 20px 16px; }
  .modal-card { max-width: 100%; }
}