.gf2-book-view{background:#f4f7f9;color:#102b40;min-height:100vh;padding-bottom:64px;overflow-x:hidden}
.gf2-book-view>.bar{background:#0d3045}.gf2-book-view>.bar small{color:#62dcb9}.gf2-book-view>.bar h2{color:#fff!important;text-shadow:none}.gf2-book-view>.bar button{background:#fff;color:#0d3045}
.gf2-book-top{position:relative;overflow:hidden;border-radius:24px;margin:14px 18px 0;min-height:340px;background:#0b263a;color:#fff;box-shadow:0 20px 55px #0b263a28}
.gf2-book-top img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;opacity:.58}
.gf2-book-top:after{content:"";position:absolute;inset:0;background:linear-gradient(90deg,#071d30f2 0%,#0b263ab8 45%,transparent 82%)}
.gf2-book-top>div{position:relative;z-index:1;max-width:660px;padding:48px}
.gf2-book-top .eyebrow{color:#63e1bb}.gf2-book-top h1{font-size:clamp(2.2rem,5vw,4.5rem);line-height:1.02;margin:8px 0 18px;color:#fff}
.gf2-book-top p{font-size:1.08rem;line-height:1.65;color:#e7f2f7}.gf2-book-progress{display:flex;gap:16px;align-items:center;margin-top:24px}.gf2-book-progress span{font-weight:800}.gf2-book-progress i{height:9px;flex:1;background:#ffffff2b;border-radius:10px;overflow:hidden}.gf2-book-progress b{display:block;height:100%;width:0;background:#35d4a3}
.gf2-book-layout{display:block;width:100%;max-width:none;margin:0;padding:30px 18px}
.gf2-book-toc{position:relative;top:auto;width:100%;margin:0 0 18px;padding:10px 12px;display:flex;align-items:center;overflow-x:auto;gap:6px;scrollbar-width:thin;background:#0d2b40;border-radius:18px;color:#dce9ef;box-shadow:0 16px 40px #0b263a1c}.gf2-book-toc h3,.gf2-book-toc small{display:none}.gf2-book-toc button{display:flex;flex:0 0 auto;width:auto;min-width:max-content;gap:10px;white-space:nowrap;text-align:left;border:0;background:transparent;color:#bbcfda;padding:10px 13px;border-radius:10px;cursor:pointer;font:inherit}.gf2-book-toc button:hover,.gf2-book-toc button.active{background:#154861;color:#fff}.gf2-book-toc button.done:before{content:'✓';color:#55dcb2}
.gf2-book-article{display:block;width:100%;max-width:none;margin:0;background:#fff;border:1px solid #dbe5ea;border-radius:22px;box-shadow:0 18px 45px #16364b12;overflow:hidden}.gf2-book-chapter{display:none;padding:clamp(24px,5vw,58px)}.gf2-book-chapter.active{display:block}.gf2-book-chapter h2{font-size:clamp(2rem,4vw,3.25rem);line-height:1.08;margin:6px 0 18px;color:#0b263a}.gf2-book-lead{font-size:1.25rem;line-height:1.65;color:#3a586c}.gf2-book-chapter p{line-height:1.75;font-size:1.03rem}.gf2-book-figure{margin:28px 0;border-radius:18px;overflow:hidden;background:#e8eff3}.gf2-book-figure img{display:block;width:100%;aspect-ratio:16/8.8;object-fit:cover}.gf2-book-figure figcaption{padding:12px 16px;color:#526c7c;font-size:.9rem;background:#eff4f6}
.gf2-explain{display:grid;grid-template-columns:1fr 1fr;gap:18px;margin:26px 0}.gf2-explain>div,.gf2-words,.gf2-practice,.gf2-safety,.gf2-notes{border-radius:16px;padding:22px}.gf2-explain>div{background:#eef8f5;border-left:4px solid #22b987}.gf2-explain h3,.gf2-words h3,.gf2-practice h3,.gf2-safety h3,.gf2-notes h3{margin:0 0 10px;color:#0c2b3e}.gf2-words{background:#eef5fb;border-left:4px solid #2e8ccc;margin:24px 0}.gf2-words dl{display:grid;grid-template-columns:140px 1fr;gap:10px 16px;margin:0}.gf2-words dt{font-weight:900;color:#0b5579}.gf2-words dd{margin:0;line-height:1.55}.gf2-practice{background:#f0fbf5;border:1px solid #bfead8;margin:24px 0}.gf2-safety{background:#fff7e5;border:1px solid #f0d490;margin:24px 0}.gf2-notes{background:#f7f9fa;border:1px solid #d7e2e8;margin-top:28px}.gf2-notes textarea{width:100%;min-height:130px;margin-top:10px;border:1px solid #afc4d0;background:#fff;color:#102b40;border-radius:12px;padding:14px;font:inherit;resize:vertical}
.gf2-schematic{background:#f9fbfc;border:1px solid #cfdee6;border-radius:18px;padding:24px;margin:26px 0}.gf2-schematic h3{margin-top:0}.gf2-circuit{display:grid;grid-template-columns:72px 1fr 90px;gap:12px;align-items:center;min-height:110px;color:#0b263a}.gf2-wire{height:4px;background:#133e55;position:relative}.gf2-switch{height:54px;position:relative;border-left:4px solid #133e55;border-right:4px solid #133e55}.gf2-switch:after{content:"";position:absolute;height:4px;width:62px;background:#ea8c24;left:0;top:11px;transform:rotate(-20deg);transform-origin:left}.gf2-lamp{width:64px;height:64px;border:4px solid #133e55;border-radius:50%;display:grid;place-items:center;font-weight:900;background:#fff2b8}.gf2-paths{display:grid;gap:12px}.gf2-path{height:13px;border-radius:8px;background:#dbe8ee;overflow:hidden}.gf2-path i{display:block;height:100%;background:#32c99b}
.gf2-report-example{margin:28px 0;padding:22px;border-radius:18px;background:#f8fafb;border:1px solid #d5e2e8}.gf2-report-example>h3{margin:0 0 8px}.gf2-diagram-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;margin:18px 0}.gf2-diagram-open{width:100%;min-width:0;border:1px solid #cadbe3;background:#fff;border-radius:14px;padding:12px;cursor:zoom-in;color:#12364a;box-shadow:0 8px 22px #16364b0e}.gf2-diagram-open:hover{border-color:#19a980;box-shadow:0 10px 25px #0c8f6c1d}.gf2-diagram-open img{display:block;width:100%;height:clamp(150px,24vw,260px);object-fit:contain;background:#fff}.gf2-diagram-open span{display:block;margin-top:9px;font-weight:850;text-align:center}.gf2-diagram-wide{grid-column:1/-1}.gf2-diagram-dialog{width:min(96vw,1400px);height:min(94vh,980px);border:0;border-radius:18px;padding:0;background:#0a2131;color:#fff;box-shadow:0 30px 90px #0008}.gf2-diagram-dialog::backdrop{background:#06141fd9}.gf2-diagram-dialog>div{height:100%;display:flex;flex-direction:column;padding:42px 18px 16px}.gf2-diagram-dialog img{display:block;flex:1;min-height:0;width:100%;object-fit:contain;background:#fff;border-radius:10px}.gf2-diagram-dialog p{margin:10px 0 0;text-align:center;color:#d9e8ee}.gf2-diagram-close{position:absolute;right:12px;top:10px;z-index:2;width:38px;height:38px;border:0;border-radius:50%;background:#fff;color:#0a2638;font-size:1.7rem;cursor:pointer}
.gf2-light-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:14px;margin:22px 0}.gf2-light-grid div{padding:18px;border:1px solid #d7e4e9;border-radius:14px}.gf2-light-grid b{display:block;color:#087d62;font-size:1.2rem;margin-bottom:6px}
.gf2-book-controls{display:flex;justify-content:space-between;gap:12px;padding:22px clamp(24px,5vw,58px);border-top:1px solid #e2eaee;background:#f8fafb}.gf2-book-controls button,.gf2-quiz button{border:0;border-radius:11px;padding:13px 18px;font-weight:850;cursor:pointer}.gf2-book-controls .next{background:#079b72;color:#fff}.gf2-book-controls .prev{background:#e6eef2;color:#17394d}.gf2-book-controls button:disabled{opacity:.35}
.gf2-book-controls-inline{margin:30px 0 18px;border:1px solid #d8e4e9;border-radius:16px}
.gf2-quiz{margin-top:26px;border-top:1px solid #dce7ec;padding-top:24px}.gf2-quiz-options{display:grid;gap:10px}.gf2-quiz-options button{text-align:left;background:#eff5f7;color:#17394d;border:1px solid #d4e1e7}.gf2-quiz-options button.correct{background:#dff8ed;border-color:#42c697}.gf2-quiz-options button.wrong{background:#fff0ef;border-color:#e78780}.gf2-quiz-result{padding:14px;border-radius:12px;margin-top:12px;background:#eef6fa}
@media(max-width:1500px){.gf2-book-layout{display:block!important;width:100%!important;max-width:none!important;margin:0!important;padding:24px 18px!important}.gf2-book-toc{position:relative!important;top:auto!important;width:100%!important;margin:0 0 18px!important;padding:10px 12px!important;display:flex!important;align-items:center!important;overflow-x:auto!important;gap:6px;scrollbar-width:thin}.gf2-book-toc h3,.gf2-book-toc small{display:none}.gf2-book-toc button{flex:0 0 auto;width:auto!important;min-width:max-content;white-space:nowrap;padding:10px 13px}.gf2-book-article{display:block!important;width:100%!important;max-width:none!important;margin:0!important}.gf2-book-chapter{width:auto!important;max-width:none!important;margin:0!important}}
@media(max-width:820px){.gf2-book-top{margin:8px;min-height:390px}.gf2-book-top>div{padding:30px 24px}.gf2-book-layout{display:block;padding:16px 8px}.gf2-book-toc{position:relative;top:auto;margin-bottom:16px;display:flex;overflow:auto;gap:6px}.gf2-book-toc h3,.gf2-book-toc small{display:none}.gf2-book-toc button{width:auto;min-width:max-content}.gf2-explain,.gf2-light-grid,.gf2-diagram-grid{grid-template-columns:1fr}.gf2-diagram-wide{grid-column:auto}.gf2-diagram-open img{height:auto;max-height:48vh}.gf2-words dl{grid-template-columns:1fr}.gf2-book-chapter{padding:26px 20px}.gf2-book-controls{padding:18px 20px}.gf2-book-top:after{background:linear-gradient(0deg,#071d30f1 0%,#071d309e 75%,transparent)}.gf2-diagram-dialog{width:100vw;height:100dvh;max-width:none;max-height:none;border-radius:0;margin:0}.gf2-diagram-dialog>div{padding:54px 8px 10px}}