/* ── Electrical Wiring Simulator & Trainer ───────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:        #0d1117;
  --surface:   #161b27;
  --surface2:  #1f2535;
  --border:    #2a3050;
  --accent:    #f5a623;
  --accent-lo: rgba(245,166,35,.22);
  --green:     #3ddc84;
  --red:       #ff5555;
  --gold:      #f5c842;
  --text:      #dde3f0;
  --text-dim:  #6b7a99;
  /* conductor colours (IEC harmonised) */
  --wire-l:    #b5651d;  /* brown  — Line  */
  --wire-n:    #3f8cff;  /* blue   — Neutral */
  --wire-e:    #43c66a;  /* green-yellow — Earth */
  --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: 1040px; 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, #f5a623 0%, #ffd27a 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: #1a1a2e; box-shadow: 0 0 12px var(--accent-lo); }
.pill:hover:not(.active) { background: var(--surface2); color: var(--text); }

/* ── Buttons ───────────────────────────────────────────────── */
.btn {
  padding: 8px 16px; 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: #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); }
.btn.on { background: var(--green); color: #08210f; }

/* ── 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: none; border-radius: 8px; }
.canvas-card canvas.grabbing { cursor: grabbing; }
.wire-hint {
  position: absolute; left: 14px; top: 14px; z-index: 2;
  font-size: 0.72rem; color: var(--text-dim); background: rgba(13,17,23,.72);
  border: 1px solid var(--border); border-radius: 20px; padding: 5px 12px; pointer-events: none;
  max-width: calc(100% - 28px);
}

/* ── In-canvas edit tools (bottom overlay) ─────────────────── */
.canvas-tools {
  position: absolute; left: 50%; bottom: 12px; transform: translateX(-50%); z-index: 3;
  display: flex; align-items: center; gap: 4px;
  background: rgba(22,27,39,.92); border: 1px solid var(--border);
  border-radius: 12px; padding: 5px 7px; box-shadow: 0 6px 18px rgba(0,0,0,.45);
  backdrop-filter: blur(4px);
}
.ct-btn {
  width: 36px; height: 36px; border: 1px solid transparent; border-radius: 8px;
  background: var(--surface2); color: var(--text); cursor: pointer;
  font-size: 1.1rem; line-height: 1; display: flex; align-items: center; justify-content: center;
  transition: background .15s, color .15s, border-color .15s, opacity .15s;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
}
.ct-btn:hover { background: var(--accent-lo); color: var(--accent); border-color: var(--accent); }
.ct-btn:active { transform: scale(.94); }
.ct-btn:disabled { opacity: .32; cursor: not-allowed; }
.ct-btn:disabled:hover { background: var(--surface2); color: var(--text); border-color: transparent; }
.ct-btn.ct-danger:hover { background: rgba(255,85,85,.15); color: var(--red); border-color: var(--red); }
.ct-sep { width: 1px; height: 22px; background: var(--border); margin: 0 3px; }

/* ── Workbench toolbar ─────────────────────────────────────── */
#sim-wrap { display: flex; flex-direction: column; gap: 14px; }
.wb-toolbar {
  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);
}
.wb-gen { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.wb-spacer { flex: 1 1 auto; }
.wb-select {
  background: var(--bg); color: var(--text); border: 1px solid var(--border);
  border-radius: 8px; padding: 7px 10px; font-size: 0.82rem; font-family: var(--font);
  cursor: pointer; outline: none; max-width: 220px;
}
.wb-select:focus { border-color: var(--accent); }
.wb-fault-toggle { display: inline-flex; align-items: center; gap: 6px; font-size: 0.78rem; color: var(--text-dim); cursor: pointer; }
.wb-fault-toggle input { accent-color: var(--accent); width: 15px; height: 15px; }
.wb-volts .pill { padding: 5px 11px; font-size: 0.78rem; }

/* ── Readout badges ────────────────────────────────────────── */
.readout-badges { display: flex; flex-wrap: wrap; gap: 8px; }
.readout-badge {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 7px 13px; border-radius: 22px;
  background: var(--surface); border: 1px solid var(--border);
  font-size: 0.8rem; color: var(--text-dim);
}
.readout-badge strong { color: var(--text); font-family: var(--mono); font-size: 0.92rem; margin-left: 2px; }
.rb-dot { width: 10px; height: 10px; border-radius: 50%; flex: none; box-shadow: 0 0 6px currentColor; }

/* ── Fault / status strip ──────────────────────────────────── */
.fault-strip { display: flex; flex-direction: column; gap: 6px; }
.fault-strip:empty { display: none; }
.fault-item {
  display: flex; align-items: flex-start; gap: 8px;
  font-size: 0.82rem; line-height: 1.5;
  padding: 9px 13px; border-radius: 8px; border: 1px solid var(--border);
  border-left-width: 3px; background: var(--surface2);
}
.fault-item .fi-icon { flex: none; font-size: 0.95rem; }
.fault-item.ok     { border-left-color: var(--green); color: var(--text); }
.fault-item.warn   { border-left-color: var(--gold);  color: var(--text); }
.fault-item.danger { border-left-color: var(--red);   color: var(--text); }
.fault-item strong { color: var(--accent); }

/* ── Build layout: left tool panel + canvas column ─────────── */
.build-layout { display: flex; gap: 14px; align-items: flex-start; }
.canvas-col { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 14px; }

/* left collapsible tool panel — block flow with its own scroll (never stretch to canvas) */
.side-panel {
  width: 216px; flex-shrink: 0; align-self: flex-start;
  position: sticky; top: 8px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 8px; display: block;
  max-height: calc(100vh - 24px); overflow-y: auto; overscroll-behavior: contain;
}
.side-panel::-webkit-scrollbar { width: 9px; }
.side-panel::-webkit-scrollbar-thumb { background: var(--surface2); border-radius: 6px; border: 2px solid var(--surface); }
.side-panel::-webkit-scrollbar-thumb:hover { background: var(--border); }
.sp-cat {
  display: flex; align-items: center; justify-content: space-between;
  padding: 8px 8px; margin-top: 6px; border-radius: 7px; cursor: pointer; user-select: none;
  font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: .05em;
  color: var(--accent); background: var(--surface2); transition: background .15s;
  position: sticky; top: 0; z-index: 1;
}
.sp-cat:first-child { margin-top: 0; }
.sp-cat:hover { background: var(--border); }
.sp-arrow { font-size: 0.6rem; transition: transform .2s; }
.sp-cat.collapsed .sp-arrow { transform: rotate(-90deg); }
.sp-cat-items { overflow: hidden; transition: max-height .25s ease; max-height: 1200px; padding: 8px 2px; }
.sp-cat.collapsed + .sp-cat-items { max-height: 0; padding: 0 2px; }

.palette { display: grid; grid-template-columns: repeat(auto-fill, minmax(84px, 1fr)); gap: 8px; }
.palette-item {
  display: flex; flex-direction: column; align-items: center; gap: 5px;
  padding: 9px 6px; border: 1px solid var(--border); border-radius: 10px;
  background: var(--surface2); color: var(--text); cursor: pointer;
  transition: border-color .15s, background .15s, transform .1s;
  touch-action: manipulation; -webkit-tap-highlight-color: transparent;
}
.palette-item:hover { border-color: var(--accent); background: rgba(245,166,35,.08); }
.palette-item:active { transform: scale(.96); }
.palette-item .pi-ico { width: 40px; height: 34px; display: block; }
.palette-item .pi-name { font-size: 0.68rem; text-align: center; line-height: 1.15; color: var(--text-dim); }
.palette-item:hover .pi-name { color: var(--text); }

/* ── Cable builder ─────────────────────────────────────────── */
.cable-builder { display: flex; flex-direction: column; gap: 9px; }
.cb-row { display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.cb-row > span { font-size: 0.78rem; color: var(--text-dim); flex: none; }
.cb-row .wb-select { flex: 1; max-width: none; }
.cb-preview {
  height: 46px; border-radius: 8px; background: var(--bg);
  border: 1px solid var(--border); display: flex; align-items: center; justify-content: center;
}
.cb-rating {
  font-size: 0.8rem; color: var(--text); font-family: var(--mono);
  background: var(--bg); border: 1px solid var(--border); border-radius: 8px;
  padding: 8px 12px; line-height: 1.5;
}
.cb-rating b { color: var(--accent); }
.cb-add { width: 100%; }

/* ── Inspector ─────────────────────────────────────────────── */
.inspector {
  background: var(--bg); border: 1px solid var(--border); border-radius: 8px;
  padding: 12px 14px; min-height: 60px; display: flex; flex-direction: column; gap: 10px;
}
.insp-empty { font-size: 0.8rem; color: var(--text-dim); line-height: 1.5; }
.insp-title { font-size: 0.9rem; font-weight: 700; color: var(--text); }
.insp-sub { font-size: 0.74rem; color: var(--text-dim); }
.insp-row { display: flex; align-items: center; gap: 10px; }
.insp-row label { font-size: 0.76rem; color: var(--text-dim); min-width: 74px; }
.insp-row .insp-val { font-family: var(--mono); font-size: 0.85rem; font-weight: 700; color: var(--accent); min-width: 64px; text-align: right; }

/* ── Slider (used in inspector) ────────────────────────────── */
.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;
}
.insp-select {
  background: var(--surface2); color: var(--text); border: 1px solid var(--border);
  border-radius: 6px; padding: 6px 8px; font-size: 0.8rem; cursor: pointer; flex: 1;
}

/* ── 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(165px, 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(245,166,35,.45); color: var(--text); }
.is-btn.active { border-color: var(--accent); color: #fff; background: rgba(245,166,35,.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; }

.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; }
.ii-desc strong { color: var(--text); }
.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: 1.05rem; 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); }

/* ── 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-choices { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 4px; }
.pp-choice {
  padding: 12px 14px; border: 2px solid var(--border); border-radius: 10px;
  background: var(--surface2); color: var(--text); font-size: 0.85rem; font-weight: 600;
  cursor: pointer; text-align: left; transition: border-color .18s, background .18s, color .18s;
}
.pp-choice:hover:not(.locked) { border-color: var(--accent); background: rgba(245,166,35,.06); }
.pp-choice.correct { border-color: var(--green); background: rgba(61,220,132,.12); color: var(--green); }
.pp-choice.wrong { border-color: var(--red); background: rgba(255,85,85,.08); color: var(--red); }
.pp-choice.locked { cursor: default; }
.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); }
.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: 0.9rem; 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(245,166,35,.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-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); }
.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; }

/* ── Calc FAB + 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, #f7b84e, #f5a623);
  color: #1a1a2e; 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; 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; }
.calc-modal-close:hover { border-color: var(--accent); color: var(--text); }
.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-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: #1a1a2e; 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-result { font-size: 0.88rem; color: var(--text-dim); }
.cs-result strong { font-family: var(--mono); font-size: 0.95rem; color: var(--green); }

/* ── Learning panel ────────────────────────────────────────── */
.learn-panels { margin-top: 2px; 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-card { border: 1px solid var(--border); border-radius: 10px; background: var(--bg); overflow: hidden; }
.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::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; }

/* ── 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: 170px; 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); }

/* ── 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);color:var(--text);border:1.5px solid var(--border);white-space:nowrap;transition:border-color .18s,background .18s,color .18s;}
.btn-link:hover{border-color:var(--accent);background:var(--accent-lo);color:#fff;}
.btn-link img{width:20px;height:20px;border-radius:4px;flex:none;}
.btn-link .lbl{line-height:1;}

/* ── Responsive ────────────────────────────────────────────── */
@media (max-width: 768px) {
  .build-layout { flex-direction: column; }
  .side-panel { width: 100%; align-self: stretch; max-height: 300px; position: static; }
  .sp-cat { position: static; }
  .answer-grid { grid-template-columns: 1fr 1fr; }
  .is-grid { grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); }
  .controls-bar { gap: 10px; }
  .btn-calc-fab { padding: 8px 12px; font-size: 0.78rem; }
  .btn-link .lbl { display: none; }
}
@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; }
  .pp-choices { grid-template-columns: 1fr; }
  .is-grid { grid-template-columns: 1fr 1fr; }
  .palette { grid-template-columns: repeat(auto-fill, minmax(72px, 1fr)); }
  .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; }
  .wire-hint { font-size: 0.66rem; padding: 4px 9px; }
  .feature-table { font-size: 0.76rem; }
}