/* eCircuitCalc — First Circuits tutorial (reuses base.css tokens/components) */

/* Reading progress */
.rprog{position:fixed;top:0;left:0;right:0;height:3px;z-index:120;pointer-events:none}
.rprog span{display:block;height:100%;width:0;background:var(--grad);transition:width .1s linear}

/* Sticky in-page module nav */
.dsg-bar{position:sticky;top:var(--nav-h,64px);z-index:90;background:color-mix(in srgb,var(--bg) 84%,transparent);
  backdrop-filter:blur(12px);-webkit-backdrop-filter:blur(12px);border-bottom:1px solid var(--border)}
.dsg-chips{display:flex;gap:.4rem;overflow-x:auto;padding:.6rem 0 .75rem;scrollbar-width:thin;scrollbar-color:var(--border2) transparent}
.dsg-chips::-webkit-scrollbar{height:6px}
.dsg-chips::-webkit-scrollbar-thumb{background:var(--border2);border-radius:99px}
.dsg-chip{flex:none;font-size:.82rem;padding:.45rem .85rem;border-radius:999px;border:1px solid var(--border);
  color:var(--text2);background:var(--surface);white-space:nowrap;transition:transform .2s var(--ease),color .2s,border-color .2s}
.dsg-chip:hover{color:var(--accent);border-color:var(--accent);transform:translateY(-1px)}
.dsg-chip.active{color:#fff;background:var(--grad);border-color:transparent}

/* Prose */
.prose{width:min(1120px,92%);margin:0 auto;display:grid;gap:clamp(2.4rem,5vw,3.4rem);padding:1.5rem 0 2rem}
.prose section{scroll-margin-top:120px}
.prose h2{font-size:clamp(1.35rem,3vw,1.8rem);font-weight:800;letter-spacing:-.02em;margin-bottom:.9rem}
.prose h3{font-size:1.05rem;margin:1.2rem 0 .5rem}
.prose p{color:var(--text2);line-height:1.72;margin-bottom:.9rem}
.prose ul,.prose ol{color:var(--text2);line-height:1.7;margin:0 0 .9rem 1.2rem}
.prose li{margin-bottom:.35rem}
.prose a{color:var(--accent);text-decoration:underline;text-underline-offset:3px}
.muted{color:var(--text2);font-size:.92rem}

/* Callouts */
.callout{border:1px solid var(--border);border-left:3px solid var(--accent);background:var(--surface);
  border-radius:0 12px 12px 0;padding:1rem 1.2rem;margin:1.1rem 0}
.callout p{margin:0}
.callout .tag{display:inline-block;font-family:var(--mono);font-size:.62rem;letter-spacing:.12em;text-transform:uppercase;margin-bottom:.4rem;font-weight:600}
.callout.pitfall{border-left-color:#fbbf24}
.callout.pitfall .tag{color:#fbbf24}
.callout.takeaway{border-left-color:var(--accent);background:color-mix(in srgb,var(--accent) 8%,var(--surface))}
.callout.takeaway .tag{color:var(--accent)}

/* Formula */
.formula{font-family:var(--mono);font-size:1.02rem;color:var(--accent);background:var(--surface);
  border:1px solid var(--border);border-radius:10px;padding:.85rem 1rem;margin:.9rem 0;overflow-x:auto;white-space:nowrap}

/* Ohm's triangle */
.ohm-tri{width:150px;margin:.4rem auto 1rem;display:block}
.ohm-tri svg{width:100%;height:auto;display:block}
.ohm-tri .tri-v{fill:var(--accent);font:800 24px var(--mono)}
.ohm-tri .tri-x{fill:var(--text);font:800 20px var(--mono)}

/* Tables (base provides table/.table-wrap) */

.fn{color:var(--accent);font-size:.7em;vertical-align:super;cursor:help;font-family:var(--mono)}

.table-wrap{overflow-x:auto;border:1px solid var(--border);border-radius:14px;background:var(--surface);margin:1.2rem 0}
table{width:100%;border-collapse:collapse}
.spec{min-width:460px}
.spec.small{min-width:320px}
.spece caption{caption-side:top;text-align:left;padding:.9rem 1.1rem .3rem;font-family:var(--mono);
  font-size:.7rem;letter-spacing:.08em;text-transform:uppercase;color:var(--text2)}
.spec th,.cmp-table td{padding:.7rem 1rem;text-align:left;border-bottom:1px solid var(--border);font-size:.92rem}
.spec th{font-family:var(--mono);font-size:.7rem;letter-spacing:.08em;text-transform:uppercase;color:var(--text2);background:var(--surface2)}
.spec tbody tr:last-child td{border-bottom:0}



/* Figure / SVG */
.fig{padding:1.2rem;border-radius:16px;background:var(--bg2);border:1px solid var(--border)}
.fig-svg{width:100%;height:auto;max-width:720px;margin:0 auto;display:block}
.fig figcaption{margin-top:1rem;font-size:.9rem;color:var(--text2);line-height:1.6}
.fig figcaption strong{color:var(--text)}

/* Interactive tool shells */
.ohm,.ledcalc,.colcode,.meter{margin:1.2rem 0;border:1px solid var(--border);border-radius:14px;background:var(--surface);padding:1.1rem;display:grid;gap:.9rem}
.ohm h3,.ledcalc h3,.colcode h3,.meter h3{margin:0}
.ohm-solve{max-width:240px}
.ohm-inputs,.calc-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:.8rem}
.calc-out{display:flex;align-items:baseline;gap:.7rem;flex-wrap:wrap}
.calc-out .big{font-family:var(--mono);font-size:1.55rem;font-weight:800;color:var(--accent)}
.calc-out .muted{font-size:.95rem}
.ohm .muted,.ledcalc .muted{margin:0}

/* Multimeter */
.meter-btns{display:flex;flex-wrap:wrap;gap:.5rem}
.meter-btn{font-size:.82rem;font-weight:600;padding:.55rem .85rem;border-radius:10px;border:1px solid var(--border2);
  background:var(--surface2);color:var(--text2);cursor:pointer;transition:.2s}
.meter-btn:hover{color:var(--accent);border-color:var(--accent)}
.meter-btn.active{color:#fff;background:var(--grad);border-color:transparent}
.meter-panel{border-top:1px solid var(--border);padding-top:1rem}
.meter-dl{display:grid;gap:.6rem;margin:0}
.meter-dl>div{display:grid;grid-template-columns:96px 1fr;gap:.6rem;align-items:baseline}
.meter-dl dt{font-family:var(--mono);font-size:.7rem;letter-spacing:.08em;text-transform:uppercase;color:var(--text2)}
.meter-dl dd{margin:0;font-size:.92rem;color:var(--text)}
.meter-warn dd{color:#fbbf24}

/* Breadboard */
.bread{margin:1.2rem 0;border:1px solid var(--border);border-radius:14px;background:var(--surface);padding:1.1rem}
.bread-host svg{width:100%;height:auto;max-width:480px;margin:0 auto;display:block}
.bread-deco .bread-railplus{fill:rgba(248,113,113,.14);stroke:rgba(248,113,113,.45);stroke-width:1}
.bread-deco .bread-railminus{fill:rgba(96,165,250,.14);stroke:rgba(96,165,250,.45);stroke-width:1}
.bread-deco .bread-groove{fill:var(--surface2)}
.bread-deco .bread-gapline{stroke:var(--text2);stroke-width:1;stroke-dasharray:3 3}
.bread-g{cursor:pointer;outline:none}
.bread-hit{fill:transparent;pointer-events:all}
.bread-hole{fill:var(--surface2);stroke:var(--border2);stroke-width:1.5;transition:fill .15s,stroke .15s}
.bread-g:hover .bread-hole{fill:var(--accent2)}
.bread-g.on .bread-hole{fill:var(--accent);stroke:var(--accent);filter:drop-shadow(0 0 4px var(--glow))}
.bread-g:focus-visible .bread-hit{stroke:var(--accent);stroke-width:2;stroke-dasharray:4 4}
.bread-desc{margin:1rem 0 0;font-size:.92rem;color:var(--text2);min-height:1.2em}

/* Ad slot (auto-hides when empty) */
.ad-slot{max-width:728px;margin:1.5rem auto;text-align:center;transition:max-height .5s var(--ease),opacity .4s,margin .5s;max-height:160px;overflow:hidden}
.ad-slot.ad-hidden{max-height:0;opacity:0;margin:0}
.ad-label{display:block;font-family:var(--mono);font-size:.6rem;letter-spacing:.2em;text-transform:uppercase;color:var(--text2);opacity:.6;margin-bottom:.4rem}
.ad-box{min-height:90px;border:1.5px dashed var(--border2);border-radius:12px;display:grid;place-items:center;color:var(--text2);font-size:.85rem;background:var(--surface)}

/* Animated circuit SVG */
.fc-wire{fill:none;stroke:var(--wbase,rgba(148,163,184,.5));stroke-width:2.5;stroke-linecap:round}
.fc-comp{fill:none;stroke:var(--text);stroke-width:2.6;stroke-linecap:round;stroke-linejoin:round}
.fc-thick{stroke-width:5}
.fc-led{fill:rgba(74,222,128,.15);stroke:var(--text)}
.fc-glow{animation:fcPulse 2s ease-in-out infinite}
.fc-flow{fill:none;stroke:var(--accent);stroke-width:2.6;stroke-linecap:round;stroke-dasharray:10 18;
  animation:fcFlow 1s linear infinite;filter:drop-shadow(0 0 4px var(--glow))}
.fc-em line{stroke:var(--text2);stroke-width:1.6}
.fc-dir path{fill:var(--accent)}
.fc-lbl{fill:var(--text);font:600 15px var(--mono)}
.fc-lbl.sm{fill:var(--text2);font-size:12px}
@keyframes fcFlow{to{stroke-dashoffset:-28}}
@keyframes fcPulse{0%,100%{opacity:.35}50%{opacity:.9}}

/* Focus + reduced motion + responsive */
.dsg-chip:focus-visible,.meter-btn:focus-visible,.back-top:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
@media (prefers-reduced-motion:reduce){
  .rprog span{transition:none}
  .fc-flow,.fc-glow{animation:none}
  .fc-glow{opacity:.6}
  .dsg-chip,.meter-btn,.bread-hole{transition:none}
}
@media (max-width:640px){
  .calc-grid,.ohm-inputs{grid-template-columns:1fr 1fr}
  .calc-out .big{font-size:1.3rem}
  .meter-dl>div{grid-template-columns:1fr;gap:.15rem}
}