#principles{scroll-margin-top:78px;overflow:hidden;padding:26px;background:#fff;border:1px solid #ccdbe7;border-radius:12px}
#principles .principle-heading{margin-bottom:18px;gap:14px}#principles .principle-heading h2{font-size:24px;letter-spacing:-.035em}
.principle-models{display:flex;gap:4px;padding:4px;border:1px solid #ccdae6;border-radius:8px}.principle-models button{min-width:76px;border:0;min-height:40px}
.principle-topic-row{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:0 0 18px;border-bottom:1px solid #dce5ed}.principle-topic-row>span{color:#5c7289;font-size:14px}
#principles .principle-modes{display:flex;gap:5px}#principles .principle-modes button{min-height:42px;font-size:15px;padding:8px 19px}
.principle-lab{display:grid;grid-template-columns:minmax(0,1fr) 340px;min-width:0}.cutaway-area{min-width:0;padding:21px 22px 18px 0;border-right:1px solid #dce5ed}.cutaway-heading{display:flex;align-items:start;justify-content:space-between;gap:14px}.cutaway-heading h3{font-size:17px;margin:0}.cutaway-heading>span{font-size:12px;color:#6b8093;white-space:nowrap;padding-top:3px}
.principle-scene{width:100%;background:radial-gradient(ellipse at 48% 50%,#f2f7fb 0,#fff 76%);min-width:0}.principle-scene>svg{display:block;width:100%;height:auto;max-height:510px;overflow:visible}.cut-part{cursor:pointer;transition:opacity .15s}.cut-part:hover{opacity:1}.cut-part:hover>rect,.cut-part:hover>path{stroke:#0b7ecd;stroke-width:2px}
.cutaway-legend{display:flex;flex-wrap:wrap;justify-content:center;gap:12px 20px;font-size:13px;color:#657c91;margin:0 0 19px}.cutaway-legend span{display:flex;align-items:center;gap:6px}.cutaway-legend i{display:inline-block;width:19px;height:3px}.legend-light{background:#dba520;box-shadow:0 0 5px #e1bc55}.legend-signal{border-bottom:4px dotted #0877d1}.legend-power{background:#bf6b0b}.legend-heat{background:#db633c}
.cutaway-parts{border-top:1px solid #e2eaf0;padding-top:13px}.cutaway-parts>p{font-size:13px;color:#60798e;margin:0 0 9px}#principle-parts{display:flex;flex-wrap:wrap;gap:6px}#principle-parts button{min-height:39px;font-size:14px;border-color:#d5e0e9;padding:7px 10px}#principle-parts button.in-step{border-color:#4296c9;color:#08578f;background:#edf7fe}
.principle-explanation{padding:21px 0 16px 23px;min-width:0}.principle-explanation>h3{font-size:24px;line-height:1.35;margin:0 0 10px;letter-spacing:-.025em}#principles #flow-caption{font-size:16px;line-height:1.75;margin:0 0 14px;color:#304b64;flex:none}
.principle-closeup{background:#f2f7fb;border:1px solid #d9e5ee;border-radius:7px;margin-bottom:13px;overflow:hidden}.principle-closeup svg{display:block;width:100%;height:auto}#principle-concept{font-size:14px;line-height:1.7;margin-bottom:15px;color:#496980}
.principle-brightness{background:#fff8e9;border:1px solid #eee0bc;padding:13px;border-radius:7px;margin-bottom:14px}.principle-brightness label{font-size:14px;font-weight:700}.principle-brightness>div{display:flex;align-items:center;gap:12px;margin:8px 0}.principle-brightness input{width:100%;min-width:0;accent-color:#b77b0a}.principle-brightness output{font-size:15px;font-weight:700;min-width:43px}.principle-brightness p{font-size:13px;line-height:1.6;color:#816836;margin:0}
.principle-part-detail{border-top:1px solid #dce5ed;padding-top:13px}.principle-part-detail>span{display:block;color:#627d92;font-size:12px;margin-bottom:4px}.principle-part-detail>strong{font-size:16px;display:block}.principle-part-detail p{font-size:14px;line-height:1.6;margin:4px 0}.principle-part-detail .principle-pinyin{color:#607a90;overflow-wrap:anywhere}.principle-related{display:flex;gap:7px;flex-wrap:wrap;margin-top:12px}.principle-related button{min-height:41px;font-size:14px}
#principles .flow-controls{border-top:1px solid #dce5ed;display:flex;gap:8px 12px;align-items:center;flex-wrap:wrap;padding:17px 0 15px;margin:0}#principles .flow-controls button{min-height:44px}#principles .flow-controls label{display:flex;align-items:center;gap:7px;font-size:14px}#principle-play-status{margin-left:auto;font-size:13px;color:#637c90}#principles .flow-repeat input{accent-color:#096ac9;width:17px;height:17px}
#principle-progress{height:3px;background:#e5edf3;overflow:hidden;margin-bottom:17px}#principle-progress i{display:block;height:100%;background:#0a77ba;width:0}#principles .flow-steps{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px;margin:0}#principles .flow-step{padding:0;display:block;overflow:hidden;border:1px solid #d3dfe9;background:#fff;color:#2f4e68;border-radius:8px;text-align:left}#principles .flow-step.active{border:2px solid #0c72b4;background:#eff8fe;color:#074d80}.flow-thumbnail{background:#f7fafc;border-bottom:1px solid #e0e9f1;height:109px;overflow:hidden;pointer-events:none}.flow-thumbnail svg{display:block;width:100%;height:100%}.flow-step-name{display:flex;gap:10px;align-items:center;padding:12px;font-size:15px;font-weight:700;line-height:1.4}.flow-step-name b{font-size:13px;letter-spacing:.04em;color:#7693a9}#principles .flow-step.active b{color:#096ac9}
.principle-notes{margin-top:19px;padding-top:15px;border-top:1px solid #e0e8ef;font-size:14px;color:#59758a}.principle-notes summary{cursor:pointer}.principle-notes p{line-height:1.75;margin:12px 0}.principle-notes>div{display:flex;gap:10px 18px;flex-wrap:wrap}
@media(min-width:1550px){.principle-lab{grid-template-columns:minmax(0,1fr) 370px}.principle-explanation{padding-left:27px}.principle-scene>svg{max-height:535px}}
@media(max-width:1080px){.principle-lab{grid-template-columns:minmax(0,1fr) 300px}.cutaway-area{padding-right:15px}.principle-explanation{padding-left:17px}.cutaway-heading{display:block}.cutaway-heading>span{display:block;margin-top:4px}.principle-topic-row{align-items:flex-start;flex-direction:column;gap:8px}}
@media(max-width:850px){.principle-lab{grid-template-columns:1fr}.cutaway-area{border-right:0;padding:17px 0}.principle-explanation{border-top:1px solid #dce5ed;padding:18px 0;display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);column-gap:20px;align-items:start}.principle-explanation>.eyebrow,.principle-explanation>h3,#flow-caption,#principle-concept{grid-column:1}.principle-closeup{grid-column:2;grid-row:1 / span 4}.principle-brightness{grid-column:2;grid-row:5 / span 3}.principle-part-detail,.principle-related{grid-column:1}.principle-explanation>h3{font-size:22px}.principle-scene>svg{max-height:430px}#principle-play-status{flex-basis:100%;margin:0}}
@media(max-width:600px){#principles{padding:18px 13px;scroll-margin-top:72px}#principles .principle-heading{flex-direction:row;align-items:center}#principles .principle-heading h2{font-size:20px}.principle-models button{min-width:51px;padding:8px}.principle-models{padding:2px}#principles .principle-modes{width:100%}#principles .principle-modes button{flex:1;font-size:14px;padding:9px 8px}.principle-topic-row{padding-bottom:13px;width:100%}.principle-explanation{display:block}.principle-explanation>h3{font-size:23px}.principle-scene>svg{max-height:none}.cutaway-heading h3{font-size:16px}.cutaway-heading>span{font-size:12px}.cutaway-legend{gap:9px 14px;margin-bottom:14px}.cutaway-parts>p{font-size:13px}#principle-parts button{min-height:43px;font-size:14px}.principle-closeup{max-width:420px;margin:15px auto}.principle-brightness{margin:14px 0}.principle-related button{flex:1;min-height:44px}#principles .flow-steps{grid-template-columns:1fr 1fr;gap:9px}.flow-thumbnail{height:98px}.flow-step-name{padding:10px;font-size:14px;gap:7px}#principles .flow-controls{gap:9px}#principles .flow-controls button{font-size:14px;padding:8px 12px}.principle-notes a{line-height:1.8}}
@media(prefers-reduced-motion:reduce){.cut-part{transition:none}}
.cut-selected{filter:drop-shadow(0 0 3px #0877d177)}.cut-selected>rect,.cut-selected>path{stroke:#0877d1;stroke-width:2px}