/* ── Screw Thread Nomenclature Trainer ───────────────────────── */
:root {
  --accent:    #ef6c00;
  --accent-lo: rgba(239,108,0,.22);
  --major:     #4fc3f7;
  --minor:     #81c784;
  --pitch-col: #ffb74d;
  --depth:     #ef5350;
  --angle:     #26c6da;
  --helix:     #a78bfa;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body {
  background: var(--bg); color: var(--text);
  font-family: var(--font); min-height: 100vh; padding: 0 16px;
}
#app { max-width: 1140px; margin: 0 auto; }

/* ── Shared (header, controls, buttons) ────────────────────── */
header { text-align: center; padding: 4px 0; }
header h1 {
  font-size: 1.8rem; font-weight: 700;
  background: linear-gradient(120deg, #ef6c00 0%, #ffb74d 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 {
  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: #fff; box-shadow: 0 0 12px var(--accent-lo); }
.pill:hover:not(.active) { background: var(--surface2); color: var(--text); }

.lc-badge {
  font-size: 0.78rem; font-weight: 700; color: var(--accent);
  background: var(--accent-lo); border: 1px solid rgba(239,108,0,.3);
  border-radius: 6px; padding: 3px 10px;
}

.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: #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); }

/* ── Layout ─────────────────────────────────────────────────── */
.main-layout {
  display: flex; flex-direction: column; gap: 16px;
}
.canvas-card {
  width: 100%; background: var(--surface);
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 8px; position: relative;
}
.canvas-card canvas { display: block; width: 100%; height: auto; }
.sidebar {
  display: flex; flex-direction: column; gap: 12px;
  min-width: 0;
}

/* ── Thread Selector ───────────────────────────────────────── */
.fit-selector {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 12px 14px;
}
.sel-row {
  display: flex; align-items: flex-end; gap: 10px; flex-wrap: wrap;
}
.sel-group { display: flex; flex-direction: column; gap: 3px; }
.sel-label {
  font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.04em;
  color: var(--text-dim); font-weight: 600;
}
.sel-select {
  padding: 6px 10px; border: 1px solid var(--border); border-radius: 6px;
  background: var(--surface2); color: var(--text); font-size: 0.88rem;
  font-weight: 600; cursor: pointer;
}

/* ── Designation + Badge ──────────────────────────────────────── */
.desig-badge-row {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
}
.desig-display {
  font-family: 'Courier New', monospace; font-size: 1.5rem; font-weight: 700;
  color: #fff; letter-spacing: 0.02em;
}
.thread-badge {
  padding: 4px 14px; border-radius: 20px; font-size: 0.78rem;
  font-weight: 700; text-transform: uppercase; letter-spacing: 0.06em;
  background: var(--accent-lo); color: var(--accent);
  border: 1px solid rgba(239,108,0,.35);
}

/* ── Pitch Presets ──────────────────────────────────────────── */
.pitch-presets {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 10px 14px;
}
.preset-btns {
  display: flex; flex-wrap: wrap; gap: 6px; margin-top: 6px;
}
.preset-btn {
  padding: 6px 14px; border: 1px solid var(--border); border-radius: 6px;
  background: var(--surface2); color: var(--text-dim); font-size: 0.82rem;
  font-weight: 600; cursor: pointer; transition: all .18s; white-space: nowrap;
  font-family: 'Courier New', monospace;
}
.preset-btn:hover { background: var(--border); color: var(--text); }
.preset-btn.active {
  background: var(--accent); color: #fff; border-color: var(--accent);
  box-shadow: 0 0 10px var(--accent-lo);
}
.preset-type {
  font-size: 0.68rem; font-weight: 400; opacity: 0.8;
  margin-left: 4px; text-transform: uppercase; letter-spacing: 0.03em;
  font-family: system-ui, sans-serif;
}

/* ── Pitch Slider ──────────────────────────────────────────── */
.pitch-slider-wrap {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 12px 14px;
}
.pitch-slider-header {
  display: flex; justify-content: space-between; align-items: center;
  margin-bottom: 8px;
}
.pitch-val {
  font-family: 'Courier New', monospace; font-size: 1.1rem;
  font-weight: 700; color: var(--accent);
}
.pitch-slider {
  -webkit-appearance: none; appearance: none;
  width: 100%; height: 6px; border-radius: 3px;
  background: var(--surface2); outline: none;
}
.pitch-slider::-webkit-slider-thumb {
  -webkit-appearance: none; appearance: none;
  width: 22px; height: 22px; border-radius: 50%;
  background: var(--accent); cursor: pointer;
  box-shadow: 0 0 8px var(--accent-lo);
  border: 2px solid #fff; transition: box-shadow .15s;
}
.pitch-slider::-webkit-slider-thumb:hover {
  box-shadow: 0 0 14px var(--accent-lo);
}
.pitch-slider::-moz-range-thumb {
  width: 22px; height: 22px; border-radius: 50%;
  background: var(--accent); cursor: pointer;
  border: 2px solid #fff; box-shadow: 0 0 8px var(--accent-lo);
}
.pitch-slider::-moz-range-track {
  height: 6px; border-radius: 3px; background: var(--surface2);
}
.pitch-slider-range {
  display: flex; justify-content: space-between;
  font-size: 0.72rem; color: var(--text-dim); margin-top: 4px;
  font-family: 'Courier New', monospace;
}

/* ── Change Indicator ──────────────────────────────────────── */
.change-indicator {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 10px 14px;
  font-size: 0.78rem; line-height: 1.6; color: var(--text-dim);
}
.change-indicator .ci-fixed {
  color: var(--major); font-weight: 600;
}
.change-indicator .ci-changes {
  color: var(--accent); font-weight: 600;
}

/* ── Thread Badge Variants ─────────────────────────────────── */
.thread-badge.fine {
  background: rgba(79,195,247,.15); color: var(--major);
  border-color: rgba(79,195,247,.3);
}
.thread-badge.custom {
  background: rgba(167,139,250,.15); color: var(--helix);
  border-color: rgba(167,139,250,.3);
}

/* ── Result Value States ───────────────────────────────────── */
.rc-val.rc-fixed { opacity: 0.6; }
.rc-val.rc-changing { transition: color .15s; }

/* ── Results Grid ───────────────────────────────────────────── */
.results-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 10px;
}
.result-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; padding: 10px 12px; position: relative;
}
.result-card::before {
  content: ''; position: absolute; top: 0; left: 0; right: 0;
  height: 3px; border-radius: 10px 10px 0 0;
}
.rc-diameters::before { background: var(--major); }
.rc-profile::before   { background: var(--accent); }
.rc-header {
  font-size: 0.78rem; font-weight: 700; text-transform: uppercase;
  color: var(--text-dim); margin-bottom: 6px; letter-spacing: 0.04em;
}
.rc-row {
  display: flex; justify-content: space-between; align-items: center;
  padding: 3px 0; font-size: 0.82rem;
}
.rc-row span:first-child { color: var(--text-dim); }
.rc-val { font-family: 'Courier New', monospace; font-weight: 700; color: var(--text); }

/* ── Step-by-step Panel ─────────────────────────────────────── */
.step-panel {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); overflow: hidden;
}
.step-toggle {
  padding: 10px 14px; cursor: pointer; font-size: 0.82rem;
  font-weight: 700; color: var(--text-dim); list-style: none;
  user-select: none;
}
.step-toggle::-webkit-details-marker { display: none; }
.step-toggle::before {
  content: '\25B6'; display: inline-block; margin-right: 8px;
  font-size: 0.7rem; transition: transform .2s;
}
details[open] .step-toggle::before { transform: rotate(90deg); }
.step-content { padding: 0 14px 12px; }
.calc-step {
  display: flex; gap: 10px; padding: 8px 0;
  border-bottom: 1px solid rgba(42,48,80,.4);
}
.calc-step:last-child { border-bottom: none; }
.cs-num {
  flex: 0 0 22px; height: 22px; border-radius: 50%;
  background: var(--accent); color: #fff; font-size: 0.72rem;
  font-weight: 700; display: flex; align-items: center; justify-content: center;
}
.cs-body { flex: 1; min-width: 0; }
.cs-title { font-size: 0.78rem; font-weight: 700; color: var(--text-dim); margin-bottom: 2px; }
.cs-text { font-size: 0.8rem; line-height: 1.5; color: var(--text); }

/* ── Practice Panel ─────────────────────────────────────────── */
.p-question {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 14px;
  font-size: 0.92rem; line-height: 1.5;
}
.pi-group {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 10px 12px; margin-top: 8px;
}
.pi-label-row { margin-bottom: 6px; }
.pi-label {
  font-size: 0.72rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.04em; padding: 2px 8px; border-radius: 4px;
}
.pi-dim-label { background: var(--accent-lo); color: var(--accent); }
.pi-row {
  display: flex; align-items: center; gap: 8px; margin-top: 5px;
}
.pi-row label {
  width: 34px; font-size: 0.78rem; color: var(--text-dim); font-weight: 600;
}
.pi-input {
  flex: 1; padding: 7px 10px; border: 1.5px solid var(--border);
  border-radius: 6px; background: var(--surface2); color: var(--text);
  font-size: 0.88rem; font-family: 'Courier New', monospace;
  transition: border-color .18s;
}
.pi-input:focus { outline: none; border-color: var(--accent); }
.pi-ok { border-color: #3ddc84 !important; background: rgba(61,220,132,.06) !important; }
.pi-err { border-color: #ff5555 !important; background: rgba(255,85,85,.06) !important; }
.pi-unit { font-size: 0.78rem; color: var(--text-dim); width: 26px; }

.practice-actions {
  display: flex; align-items: center; gap: 10px; margin-top: 10px; flex-wrap: wrap;
}
.pbar-score {
  font-size: 0.82rem; color: var(--text-dim); margin-left: auto;
}

/* ── Solution Panel ─────────────────────────────────────────── */
.p-solution {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 12px 14px; margin-top: 8px;
}
.sol-title {
  font-size: 0.78rem; font-weight: 700; text-transform: uppercase;
  color: var(--accent); margin-bottom: 8px;
}
.sol-row {
  display: flex; justify-content: space-between; padding: 3px 0;
  font-size: 0.82rem;
}
.sol-row span:first-child { color: var(--text-dim); }
.sol-row span:last-child { font-family: 'Courier New', monospace; }
.sol-divider {
  height: 1px; background: var(--border); margin: 6px 0;
}

/* ── Quiz Panel ─────────────────────────────────────────────── */
.qbar-counter {
  display: flex; align-items: baseline; gap: 2px;
  font-family: 'Courier New', monospace; margin-bottom: 10px;
}
.qbar-q-label { font-size: 0.72rem; color: var(--text-dim); font-weight: 700; }
.qbar-q-num   { font-size: 1.6rem; font-weight: 700; color: var(--accent); }
.qbar-q-sep   { font-size: 1rem; color: var(--text-dim); }
.qbar-q-total { font-size: 1rem; color: var(--text-dim); }

.q-designation {
  font-family: 'Courier New', monospace; font-size: 1.5rem;
  font-weight: 700; color: #fff; margin-bottom: 14px;
}
.q-section { margin-bottom: 12px; }
.q-label {
  font-size: 0.82rem; color: var(--text-dim); font-weight: 600;
  margin-bottom: 6px;
}
.qi-input {
  width: 100%; padding: 10px 12px; border: 1.5px solid var(--border);
  border-radius: 8px; background: var(--surface); color: var(--text);
  font-size: 1rem; font-family: 'Courier New', monospace;
}
.qi-input:focus { outline: none; border-color: var(--accent); }
.q-actions { display: flex; gap: 10px; margin-top: 10px; }

/* ── Quiz Result ────────────────────────────────────────────── */
.quiz-result {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px;
}
.qr-header {
  display: flex; justify-content: space-between; align-items: center;
  margin-bottom: 16px; flex-wrap: wrap; gap: 10px;
}
.qr-title { font-size: 1.1rem; font-weight: 700; }
.qr-stars { font-size: 1.3rem; color: var(--gold); }
.qr-score {
  font-family: 'Courier New', monospace; font-size: 2rem; font-weight: 700;
  text-shadow: 0 0 14px currentColor;
}
.qr-score.perfect { color: var(--gold); }
.qr-score.good    { color: #3ddc84; }
.qr-score.poor    { color: #ff5555; }
.qr-verdict { font-size: 0.85rem; color: var(--text-dim); }

.qr-row {
  display: grid; grid-template-columns: 28px 1fr 1fr 1fr 24px;
  gap: 8px; align-items: center; padding: 6px 8px;
  border-left: 3px solid transparent; border-radius: 4px;
  font-size: 0.78rem; margin-bottom: 4px;
  background: rgba(255,255,255,.02);
}
.qr-row.ok  { border-left-color: #3ddc84; }
.qr-row.err { border-left-color: #ff5555; }
.qr-q    { font-weight: 700; color: var(--text-dim); }
.qr-desig { font-family: 'Courier New', monospace; font-weight: 600; }
.qr-given { color: var(--text-dim); }
.qr-correct { font-weight: 600; }
.qr-icon { text-align: center; }

/* ── Learn Mode ────────────────────────────────────────────── */
.learn-nav {
  display: flex; align-items: center; gap: 10px; margin-bottom: 12px;
}
.learn-dots {
  flex: 1; display: flex; justify-content: center; gap: 8px;
}
.learn-dot {
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--border); border: none; cursor: pointer;
  transition: all .2s; padding: 0;
}
.learn-dot.active { background: var(--accent); box-shadow: 0 0 8px var(--accent-lo); }
.learn-dot:hover:not(.active) { background: var(--text-dim); }
.learn-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px 20px;
}
.learn-title {
  font-size: 1.1rem; font-weight: 700; color: var(--accent);
  margin-bottom: 12px; padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}
.learn-body { font-size: 0.85rem; line-height: 1.7; color: var(--text-dim); }
.learn-body strong { color: var(--text); }
.learn-body .lb-key {
  display: inline-block; padding: 1px 7px; border-radius: 4px;
  font-weight: 700; font-size: 0.82rem;
}
.lb-major  { background: rgba(79,195,247,.12); color: var(--major); }
.lb-minor  { background: rgba(129,199,132,.12); color: var(--minor); }
.lb-pitch  { background: rgba(255,183,77,.12); color: var(--pitch-col); }
.lb-depth  { background: rgba(239,83,80,.12); color: var(--depth); }
.lb-angle  { background: rgba(38,198,218,.12); color: var(--angle); }
.lb-helix  { background: rgba(167,139,250,.12); color: var(--helix); }
.learn-body ul { margin: 8px 0 8px 6px; list-style: none; }
.learn-body li { padding: 3px 0; position: relative; padding-left: 14px; }
.learn-body li::before { content: '›'; position: absolute; left: 0; color: var(--accent); font-weight: 700; }
.learn-body p { margin-bottom: 8px; }

/* ── Feedback (shared) ──────────────────────────────────────── */
.feedback, .quiz-feedback {
  margin-top: 8px; padding: 8px 12px; border-radius: 8px;
  font-size: 0.82rem; font-weight: 600;
}
.feedback:empty, .quiz-feedback:empty { display: none; }
.feedback.ok, .quiz-feedback.ok {
  background: rgba(61,220,132,.1); color: #3ddc84;
  border: 1px solid rgba(61,220,132,.25);
}
.feedback.err, .quiz-feedback.err {
  background: rgba(255,85,85,.08); color: #ff5555;
  border: 1px solid rgba(255,85,85,.2);
}

/* ── Responsive ─────────────────────────────────────────────── */
@media (max-width: 880px) {
  .results-grid { grid-template-columns: 1fr; }
}
@media (max-width: 540px) {
  .sel-row { flex-direction: column; align-items: stretch; }
  .desig-display { font-size: 1.2rem; }
  .learn-card { padding: 14px; }
  .preset-btns { gap: 4px; }
  .preset-btn { padding: 5px 10px; font-size: 0.76rem; }
  .pitch-val { font-size: 0.95rem; }
}