/* eCircuitCalc — Power & RF Design (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 */
.pwr-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)}
.pwr-chips{display:flex;gap:.4rem;overflow-x:auto;padding:.6rem 0 .75rem;scrollbar-width:thin;scrollbar-color:var(--border2) transparent}
.pwr-chips::-webkit-scrollbar{height:6px}
.pwr-chips::-webkit-scrollbar-thumb{background:var(--border2);border-radius:99px}
.pwr-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}
.pwr-chip:hover{color:var(--accent);border-color:var(--accent);transform:translateY(-1px)}
.pwr-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:1.4rem 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:.4rem}
.prose li::marker{color:var(--accent)}
.prose a{color:var(--accent);text-decoration:underline;text-underline-offset:3px}
.prose strong{color:var(--text)}
.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)}
.callout.important{border-left-color:var(--accent3);background:color-mix(in srgb,var(--accent3) 8%,var(--surface))}
.callout.important .tag{color:var(--accent3)}

/* Formula */
.formula{font-family:var(--mono);font-size:1rem;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}
.formula sub{font-size:.72em}

/* Tables */
.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}
table.spec{min-width:480px}
table.spec 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,.spec 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}
.spec .mono{font-family:var(--mono);font-size:.85rem}

/* Figure */
.fig{padding:1.2rem;border-radius:16px;background:var(--bg2);border:1px solid var(--border);position:relative;overflow:hidden;margin:1.2rem 0}
.fig-svg{width:100%;height:auto;max-width:760px;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)}

/* Hero buck SVG */
.pwr-wave{fill:none;stroke-linecap:round;stroke-linejoin:round;stroke-width:2.4}
.pwr-sw{stroke:var(--accent);filter:drop-shadow(0 0 4px var(--glow))}
.pwr-il{stroke:var(--accent3);filter:drop-shadow(0 0 4px color-mix(in srgb,var(--accent3) 40%,transparent))}
.pwr-anim{animation:pwrFlow 3s linear infinite}
@keyframes pwrFlow{to{transform:translateX(-240px)}}
.pwr-circ{stroke:var(--text);fill:none;stroke-width:2.6;stroke-linecap:round;stroke-linejoin:round}
.pwr-circ .pwr-thin{stroke-width:2}
.pwr-thin{stroke:var(--text);fill:none;stroke-width:2;stroke-linecap:round;stroke-linejoin:round}
.pwr-box{stroke:var(--text);fill:none;stroke-width:1.6}
.pwr-node{fill:var(--text)}
.pwr-diode{fill:var(--accent3);stroke:var(--accent3);stroke-width:1.5;stroke-linejoin:round}
.pwr-lbl{font:500 12px var(--mono);fill:var(--text2)}
.pwr-lbl.acc{fill:var(--accent)}
.pwr-lbl.acc3{fill:var(--accent3)}
.pwr-tiny{font-size:11px}

/* H-bridge diagram */
.hb-circ{stroke:var(--text);fill:none;stroke-width:2.4;stroke-linecap:round;stroke-linejoin:round}
.hb-box{stroke:var(--text);fill:none;stroke-width:1.6}
.hb-housing{fill:none;stroke:var(--border2);stroke-width:2}
.hb-lbl{font:600 12px var(--mono);fill:var(--text2)}
.hb-rot{transform-box:fill-box;transform-origin:center;animation:hbspin 2.4s linear infinite}
@keyframes hbspin{to{transform:rotate(360deg)}}

/* RF radiating SVG */
.rf-dipole line{stroke:var(--text);stroke-width:3;stroke-linecap:round}
.rf-dipole line[stroke-dasharray]{stroke-width:1.6}
.rf-lbl{font:600 12px var(--mono);fill:var(--text2)}
.rf-wave{transform-box:fill-box;transform-origin:center;opacity:0;animation:rfPing 3.2s ease-out infinite}
@keyframes rfPing{0%{transform:scale(.2);opacity:.85}70%{opacity:.25}100%{transform:scale(1.5);opacity:0}}
.rf-wave:nth-of-type(2){animation-delay:.8s}
.rf-wave:nth-of-type(3){animation-delay:1.6s}
.rf-wave:nth-of-type(4){animation-delay:2.4s}

/* Expandable "go deeper" */
.deep{border:1px solid var(--border);border-radius:12px;background:var(--surface);margin:1rem 0;overflow:hidden}
.deep summary{cursor:pointer;padding:.9rem 1.1rem;font-weight:600;font-size:.95rem;list-style:none;display:flex;align-items:center;gap:.55rem}
.deep summary::-webkit-details-marker{display:none}
.deep summary::before{content:"+";font-family:var(--mono);color:var(--accent);font-weight:700}
.deep[open] summary::before{content:"–"}
.deep[open] summary{border-bottom:1px solid var(--border)}
.deep summary:focus-visible{outline:2px solid var(--accent);outline-offset:-2px}
.deep .deep-body{padding:.4rem 1.1rem 1rem}
.deep .deep-body p{margin-bottom:.6rem}

/* Interactive tool shells */
.tool{margin:1.2rem 0;border:1px solid var(--border);border-radius:14px;background:var(--surface);padding:1.1rem;display:grid;gap:.9rem}
.tool h3{margin:0}
.calc-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:.8rem}
.calc-grid .field{margin:0}
.calc-out{display:flex;align-items:baseline;gap:.7rem;flex-wrap:wrap}
.calc-out .big{font-family:var(--mono);font-size:1.5rem;font-weight:800;color:var(--accent)}
.calc-out .muted{font-size:.95rem}
.tool .muted{margin:0}
.unit-row{display:flex;gap:.5rem}
.unit-row .field{flex:1;margin:0}
.unit-row select{width:auto;min-width:74px}
.tool select,.tool input{width:100%}
.unit-row .field:first-child{flex:1 1 auto}
.tool label,.calc-grid label{display:block;font-size:.82rem;font-weight:600;margin-bottom:.35rem;color:var(--text)}
.tool input,.tool select{padding:.6rem .7rem;border-radius:10px;border:1px solid var(--border2);background:var(--bg);color:var(--text);font:inherit}
.tool input:focus,.tool select:focus{outline:0;border-color:var(--accent);box-shadow:0 0 0 3px var(--glow)}

/* 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)}

/* Focus */
.pwr-chip:focus-visible,.meter-btn:focus-visible,.back-top:focus-visible{outline:2px solid var(--accent);outline-offset:2px}

/* Reduced motion */
@media (prefers-reduced-motion:reduce){
  .rprog span{transition:none}
  .pwr-anim,.hb-rot{animation:none}
  .pwr-chip,.pwr-bar .fill,.deep summary{transition:none}
  .rf-wave{animation:none;opacity:.3}
  .rf-wave:nth-of-type(1){transform:scale(.4)}
  .rf-wave:nth-of-type(2){transform:scale(.7)}
  .rf-wave:nth-of-type(3){transform:scale(1.0)}
  .rf-wave:nth-of-type(4){transform:scale(1.3)}
}

/* Responsive */
@media (max-width:640px){
  .calc-grid{grid-template-columns:1fr 1fr}
  .calc-out .big{font-size:1.25rem}
  .pwr-bar{grid-template-columns:56px 1fr 66px}
  table.spec{min-width:440px}
}