.stem-lab{--sl-ink:var(--ink);--sl-muted:var(--muted);--sl-teal:var(--green);--sl-orange:var(--brass);--sl-line:var(--line);color:var(--sl-ink);background:transparent;font-family:var(--sans);padding-bottom:60px}.stem-lab *{box-sizing:border-box}.stem-lab [hidden]{display:none!important}.stem-hero{padding-top:56px;padding-bottom:40px}.stem-kicker{color:var(--sl-teal);margin:0 0 15px}.stem-hero h1{font-family:var(--sans);font-size:clamp(2.5rem,5.8vw,4.8rem);line-height:1.08;letter-spacing:-.035em;margin:0 0 28px;max-width:1020px}.stem-hero h1 em{font-style:normal;color:var(--sl-teal)}.stem-intro{font-size:1.18rem;line-height:1.8;max-width:800px}.stem-jump{display:flex;gap:10px;flex-wrap:wrap;margin:28px 0}.stem-jump a{white-space:normal;text-align:center}.stem-jump a:hover{border-color:var(--sl-teal);color:var(--sl-teal)}.stem-model-note{padding:17px 20px;border-left:4px solid var(--sl-orange);background:var(--brass-soft);font-size:.87rem;line-height:1.7;max-width:1000px}.stem-model-note strong{display:block}.stem-section{padding-top:46px;padding-bottom:42px;scroll-margin-top:100px}.stem-section-heading{display:flex;gap:24px;max-width:960px;margin-bottom:28px}.stem-number{flex-shrink:0;white-space:nowrap;color:var(--sl-teal);font-size:2.7rem;font-weight:700;line-height:1}.stem-section-heading h2{font-family:var(--sans);font-size:clamp(1.6rem,3vw,2.35rem);line-height:1.2;letter-spacing:-.035em;margin:0 0 15px}.stem-section-heading p:last-child{font-size:1rem;line-height:1.8;margin:0}.stem-workbench{display:grid;grid-template-columns:minmax(0,1.35fr) minmax(280px,1fr);border:1px solid var(--sl-line);border-radius:0;border-top:5px solid var(--green);overflow:hidden;background:var(--white);box-shadow:var(--shadow-paper)}.stem-visual{padding:25px;min-width:0;background:var(--paper)}.stem-visual-bar{display:flex;flex-wrap:wrap;gap:8px;justify-content:space-between;align-items:center;font-size:.8rem;font-weight:700;margin-bottom:16px}.stem-pill{color:var(--sl-teal);background:var(--brass-soft);padding:5px 9px;border-radius:0;font-size:.65rem}.stem-visual svg{display:block;width:100%;height:auto;overflow:visible}.stem-visual svg .pole{font-size:16px;font-weight:700;font-family:var(--sans);text-anchor:middle}.stem-svg-numbers circle{fill:#213247;stroke:none}.stem-svg-numbers text{fill:#fff;stroke:none;font-size:15px;font-weight:700;text-anchor:middle;font-family:var(--sans)}.stem-legend{list-style:none;display:flex;flex-wrap:wrap;gap:10px 16px;margin:8px 0 18px;padding:0;font-size:.74rem}.stem-legend li{display:flex;gap:6px;align-items:center}.stem-legend b{display:grid;place-items:center;background:var(--ink);color:var(--white);border-radius:50%;width:20px;height:20px;font-size:.65rem;flex-shrink:0}.stem-caption,.stem-help{color:var(--sl-muted);font-size:.8rem;line-height:1.7}.stem-wave{background:var(--white);border:1px solid var(--sl-line);border-radius:0;padding:12px;margin-top:20px;font-size:.73rem;color:var(--sl-muted)}.wave-axis{stroke:#bdcbd0;stroke-width:1;fill:none}.wave-signal{fill:none;stroke:#276b64;stroke-width:3}.wave-limit{stroke:#b95d30;stroke-dasharray:5 5;stroke-width:1.5;fill:none}.stem-controls{padding:28px;border-left:1px solid var(--sl-line);min-width:0}.stem-controls h3{font-family:var(--sans);font-size:1.15rem;line-height:1.5;margin:0 0 25px}.stem-controls label:not(.stem-check){display:flex;justify-content:space-between;gap:10px;font-size:.85rem;font-weight:700;margin-top:22px}.stem-controls output{font-weight:400;color:var(--sl-teal);white-space:nowrap}.stem-controls input[type=range]{display:block;width:100%;height:35px;margin:7px 0;accent-color:var(--sl-teal);cursor:pointer}.stem-controls select{width:100%;padding:12px;border-radius:0;background:var(--white);color:var(--sl-ink);border:1px solid var(--line);font:inherit;margin-top:8px}.stem-buttons{display:flex;gap:8px;flex-wrap:wrap;margin-top:25px}.stem-lab button{box-shadow:3px 3px 0 var(--paper-deep);font-family:inherit;cursor:pointer;min-height:44px;font-size:.9rem;font-weight:600;line-height:1.5;padding:10px 16px;border-radius:0;border:1px solid var(--sl-line);background:var(--white);color:var(--sl-ink)}.stem-buttons button:first-child{background:var(--sl-teal);border-color:var(--sl-teal);color:var(--white)}.stem-lab button:disabled{opacity:.55;cursor:default}.stem-lab :is(button,a,input,select,summary):focus-visible{outline:3px solid var(--brass);outline-offset:4px}.stem-lab button:hover{filter:brightness(.96)}.stem-status{font-size:.84rem;line-height:1.7;border-left:3px solid var(--sl-teal);background:var(--brass-soft);padding:12px;min-height:64px}.stem-phase{font-size:.78rem;color:var(--sl-muted);min-height:2.6em;line-height:1.5}.stem-lab details{margin-top:16px;border-top:1px solid var(--sl-line);padding-top:15px}.stem-lab summary{cursor:pointer;font-size:.86rem;font-weight:700;min-height:36px;line-height:1.6}.stem-lab details p{font-size:.84rem;line-height:1.8}.stem-prompt summary{color:var(--sl-teal)}.stem-check{display:flex;gap:10px;align-items:center;font-size:.9rem;min-height:44px}.stem-check input{width:20px;height:20px;accent-color:var(--sl-teal)}.stem-chain{list-style:none;display:grid;grid-template-columns:1fr 1fr;gap:14px;margin:24px 0;padding:0}.stem-chain li{position:relative;background:var(--white);border:1px solid var(--sl-line);padding:14px 14px 14px 46px;border-radius:0;min-height:100px}.stem-chain b{position:absolute;left:14px;top:16px;font-size:1.1rem;color:var(--sl-teal)}.stem-chain strong{display:block;font-size:.86rem;margin-bottom:8px}.stem-chain span{font-size:.74rem;color:var(--sl-muted);line-height:1.6}.stem-power-path{display:flex;flex-direction:column;align-items:center;color:var(--sl-orange);font-size:.8rem;padding:8px 14px 20px;gap:8px}.stem-power-path>span:first-child{border:2px solid var(--brass);padding:8px 20px;border-radius:0;background:var(--paper);font-weight:700}.stem-power-path small{font-size:.71rem;color:var(--sl-muted);text-align:center}.stem-amp-waves{display:grid;grid-template-columns:1fr 1fr;gap:12px}.stem-amp-waves>div{padding:12px;background:var(--white);border:1px solid var(--sl-line);border-radius:0;min-width:0}.stem-amp-waves span{font-size:.73rem}.stem-detector-readout{display:grid;grid-template-columns:1.1fr 1fr;gap:15px;border-top:1px solid var(--sl-line);padding-top:20px;font-size:.8rem}.stem-detector-readout meter{width:100%;height:20px;display:block;margin:10px 0}.stem-detector-readout output{font-weight:700}.stem-alarm{display:grid;grid-template-columns:20px 1fr;align-items:center;gap:8px;background:var(--paper-deep);padding:15px;border-radius:0}.stem-alarm small{grid-column:1/-1;font-size:.67rem;line-height:1.6}.stem-led{width:14px;height:14px;border-radius:50%;background:#86978d;border:2px solid #597363}.stem-alarm[data-on=true]{background:var(--brass-soft)}.stem-alarm[data-on=true] .stem-led{background:#d97613;border-color:#a55511;box-shadow:0 0 0 4px #d9761320}.stem-range-ends{display:flex;justify-content:space-between;color:var(--sl-muted);font-size:.71rem}.stem-parts{display:grid;grid-template-columns:1fr 1fr;gap:30px}.stem-part-buttons{display:grid;grid-template-columns:1fr 1fr;gap:10px}.stem-part-buttons button{display:flex;align-items:center;gap:14px;text-align:left;min-height:68px}.stem-part-buttons button>span{color:var(--sl-teal);font-size:1.1rem;min-width:28px}.stem-part-buttons button[aria-pressed=true]{background:var(--brass-soft);border-color:var(--sl-teal)}.stem-part-detail{background:var(--ink);border-radius:0;padding:32px;color:var(--white);min-height:285px}.stem-part-symbol{font-size:2.6rem;color:var(--white)}.stem-part-detail h3{font-family:var(--sans);font-size:1.3rem;color:var(--white)}.stem-part-detail p{font-size:1rem;line-height:1.9}.stem-kit-note{max-width:1000px}.stem-sources{padding-top:30px;border-top:1px solid var(--sl-line);font-size:.84rem;line-height:1.8}.stem-sources h2{font-family:var(--sans);font-size:1.4rem}.stem-sources h3{font-size:1rem;font-family:inherit}.stem-sources li{margin:8px 0}.stem-sources a{color:var(--sl-teal)}@media(max-width:850px){.stem-workbench{grid-template-columns:1fr}.stem-controls{border-left:0;border-top:1px solid var(--sl-line)}.stem-visual{padding:20px}.stem-hero{padding-top:40px}.stem-section-heading{gap:15px}.stem-number{flex-shrink:0;white-space:nowrap;font-size:2rem}.stem-parts{grid-template-columns:1fr}.stem-section{padding-top:30px;padding-bottom:24px}.stem-chain{grid-template-columns:repeat(4,1fr)}.stem-chain li{padding:10px;min-height:120px}.stem-chain b{position:static;display:block;margin-bottom:6px}.stem-intro{font-size:1rem}}@media(max-width:520px){.stem-hero h1{font-size:clamp(2.3rem,10vw,2.8rem);letter-spacing:-.035em}.stem-controls{padding:22px}.stem-section-heading{display:block}.stem-number{flex-shrink:0;white-space:nowrap;display:block;margin-bottom:15px}.stem-visual{padding:16px}.stem-chain{grid-template-columns:1fr 1fr}.stem-chain li{min-height:100px}.stem-amp-waves{gap:8px}.stem-amp-waves>div{padding:8px}.stem-jump a{white-space:normal;text-align:center}.stem-part-buttons{gap:8px}.stem-part-buttons button{font-size:.75rem;padding:10px}.stem-part-detail{padding:24px}.stem-detector-readout{grid-template-columns:1fr}.stem-legend{font-size:.72rem}.stem-hero{padding-bottom:20px}}@media(prefers-reduced-motion:reduce){.stem-lab *{scroll-behavior:auto!important;transition:none!important;animation:none!important}}html[lang=zh-Hans] .stem-lab :is(h1,h2,h3){letter-spacing:0;line-height:1.3}html[lang=zh-Hans] .stem-kicker{letter-spacing:.025em}