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.exam-bar{display:flex;align-items:center;gap:16px;background:#fff;border:1px solid #d9d2f5;border-radius:13px;padding:12px 16px;margin-bottom:14px;color:#65539a}.exam-bar span{font-size:12px;font-weight:700}.exam-bar .exam-timer{font-size:20px;letter-spacing:1px;color:#7459bb}.exam-bar .exam-timer.urgent{color:#d66b6b}.exam-bar small{color:var(--muted);font-size:11px}.exam-submit{margin-left:auto;background:#fff0f0;color:#c86767;border-radius:8px;padding:8px 12px;font-size:11px;font-weight:700}.exam-result{text-align:center;padding:42px 20px}.exam-result h3{font-size:72px;color:var(--purple);margin:22px 0 5px}.exam-result h3 small{font-size:18px}.exam-result p{color:var(--muted);font-size:13px;line-height:1.8}.exam-result p b{color:var(--ink)}.result-tip{background:#f4f0ff;color:#6d5b9d;border-radius:10px;padding:13px;margin:22px auto;max-width:460px;font-size:12px;line-height:1.7}.exam-result .primary,.exam-result .outline{width:auto;margin:5px}.exam-result .outline{border:0}
.exam-history{margin-top:20px}.exam-history .muted-text{font-size:11px;color:var(--muted);margin:0}.exam-history-list{display:grid;gap:9px}.exam-record{display:grid;grid-template-columns:72px 1fr auto;align-items:center;gap:13px;border-top:1px solid var(--line);padding:12px 0}.exam-record-score{font-size:22px;font-weight:700;color:var(--purple)}.exam-record-score small{font-size:10px;font-weight:400}.exam-record-info strong{display:block;font-size:12px}.exam-record-info small{display:block;color:var(--muted);font-size:10px;margin-top:4px}.exam-record-time{color:var(--muted);font-size:10px;text-align:right}.mobile-nav{display:none}.topic-menu-toggle,.catalog-scrim{display:none}
.trace-diagram{display:grid;gap:6px;max-width:560px;margin:0 auto}.trace-diagram>div{display:grid;grid-template-columns:72px 1fr;column-gap:9px;text-align:left;align-items:center;background:#f8fbfc;border:1px solid #d7e5e9;border-radius:9px;padding:8px 10px}.trace-diagram b{grid-row:span 2;color:#6e8991;font-size:10px}.trace-diagram strong{color:#315c6b;font-size:12px}.trace-diagram small{color:#6d858d;font-size:10px;line-height:1.5}.trace-diagram>span{text-align:center;color:#9ab0b7;font-size:14px}
.tool-steps{display:grid;gap:5px;max-width:560px;margin:0 auto}.tool-steps>div{display:flex;align-items:center;gap:9px;text-align:left;background:#f8fbfc;border:1px solid #d7e5e9;border-radius:8px;padding:7px 10px}.tool-steps b{display:grid;place-items:center;width:20px;height:20px;border-radius:50%;background:#e5f0ff;color:#4675a8;font-size:10px}.tool-steps strong{color:#315c6b;font-size:11px;font-weight:600}.tool-steps>span{text-align:center;color:#9ab0b7;font-size:12px}
.function-diagram{display:flex;align-items:stretch;justify-content:center;gap:8px}.function-diagram>div{flex:1;background:#f8fbfc;border:1px solid #d7e5e9;border-radius:9px;padding:9px 7px}.function-diagram b,.function-diagram strong,.function-diagram small{display:block}.function-diagram b{font-size:10px;color:#78909a}.function-diagram strong{color:#315c6b;margin:5px 0;font-size:12px;word-break:break-word}.function-diagram small{font-size:10px;line-height:1.45;color:#6c838b}.function-diagram>span{align-self:center;color:#9bb1b8;font-size:11px}
.forstep-diagram{display:flex;align-items:stretch;justify-content:center;gap:7px}.forstep-diagram>div{flex:1;background:#f8fbfc;border:1px solid #d7e5e9;border-radius:9px;padding:8px 6px}.forstep-diagram>span{align-self:center;color:#9bb1b8}.forstep-diagram b,.forstep-diagram strong,.forstep-diagram small{display:block}.forstep-diagram b{font-size:10px;color:#78909a}.forstep-diagram strong{font-size:12px;color:#315c6b;margin:5px 0}.forstep-diagram small{font-size:10px;line-height:1.45;color:#6c838b}.forstep-diagram .focus-step{background:#fff7e7;border-color:#f1d49a}.forstep-return{margin-top:9px;padding:8px;border-radius:8px;background:#eef8f4;color:#3f7460;font-size:10px;line-height:1.6}

/* Responsive layout: desktop sidebar, tablet top navigation, phone single-column cards. */
@media (max-width:1100px){
  .main{padding-left:30px;padding-right:30px}
  .hero{padding-left:32px;padding-right:32px}
  .practice-layout{grid-template-columns:minmax(0,1fr) 240px}
  .exam-hero{padding-left:34px;padding-right:34px}
}
@media (max-width:820px){
  body{overflow-x:hidden}
  .app-shell{display:block}
  .sidebar{position:sticky;inset:auto;top:0;z-index:20;width:100%;height:auto;padding:12px 16px 10px;display:grid;grid-template-columns:auto 1fr;gap:10px;background:rgba(255,255,255,.96);border-right:0;border-bottom:1px solid var(--line);backdrop-filter:blur(12px)}
  .brand{margin:0;min-width:0}
  .brand-mark{width:30px;height:30px;font-size:18px}
  .brand strong{font-size:15px}
  .child-card,.side-tip,.sidebar-bottom{display:none}
  .sidebar nav{grid-column:1 / -1;display:flex;gap:5px;overflow-x:auto;overscroll-behavior-x:contain;scrollbar-width:none}
  .sidebar nav::-webkit-scrollbar{display:none}
  .nav-item{flex:0 0 auto;padding:9px 11px;font-size:11px;white-space:nowrap}
  .main{margin-left:0;width:100%;max-width:none;min-width:0;padding:25px 24px 60px}
  .topbar{margin-bottom:28px}
  .path-grid,.lower-grid,.lesson-grid{grid-template-columns:repeat(2,minmax(0,1fr))}
  .hero{min-height:260px;height:auto}
  .mindmap{overflow:hidden}
  .catalog-layout{grid-template-columns:1fr}
  .topic-list{max-height:280px}
  .practice-layout{grid-template-columns:minmax(0,1fr)}
  .practice-side{order:2}
  .exam-hero{min-height:280px}
}
@media (max-width:600px){
  .sidebar{padding:10px 12px 8px;position:relative}
  .brand span{display:none}
  .sidebar nav{display:none}
  .main{padding:18px 12px 92px}
  .topbar{align-items:flex-start;margin-bottom:22px}
  .topbar h1{font-size:18px;line-height:1.35}
  .top-actions{gap:7px}
  .top-actions button,.top-actions span{display:none}
  .top-actions i{width:30px;height:30px}
  .page-intro{display:block;margin:5px 0 22px}
  .page-intro h2{font-size:25px}
  .page-intro .summary{display:inline-flex;margin-top:14px;padding:10px 13px}
  .hero{padding:24px 20px;border-radius:18px}
  .hero h2{font-size:25px}
  .hero p{font-size:11px;line-height:1.7}
  .section-head{margin-top:27px}
  .section-head h3{font-size:16px}
  .path-grid,.lower-grid,.lesson-grid,.exam-tips{grid-template-columns:1fr}
  .path-card{padding:16px}
  .path-card h4{margin-top:15px}
  .path-card p{white-space:normal}
  .panel,.lesson,.quiz-card{min-width:0;padding:16px}
  .score-row{align-items:flex-start;gap:18px}
  .filter-row{margin:0 -12px 14px;padding:0 12px 3px;overflow-x:auto;scrollbar-width:none;scroll-snap-type:x proximity}
  .filter-row::-webkit-scrollbar{display:none}
  .filter{flex:0 0 auto;padding:10px 13px;min-height:42px;scroll-snap-align:start}
  .quiz-meta{align-items:flex-start;gap:8px;flex-direction:column}
  .quiz-card h3{font-size:16px;line-height:1.6;margin:18px 0 13px}
  pre{padding:14px;font-size:12px;line-height:1.7}
  .options{grid-template-columns:1fr;gap:8px}
  .option{padding:12px;font-size:12px}
  .question-controls{position:sticky;bottom:76px;z-index:5;margin:16px -16px -16px;padding:12px 16px;background:rgba(255,255,255,.96);box-shadow:0 -5px 16px rgba(21,42,58,.08);backdrop-filter:blur(10px)}
  .question-controls button{min-width:108px;min-height:42px;padding:8px 10px}
  .mistake-item{display:block;padding:17px}
  .mistake-num{display:block;margin-bottom:9px}
  .mistake-content h3{line-height:1.6}
  .review-btn{display:block;margin-top:14px;padding:6px 0}
  .exam-hero{padding:24px 20px;min-height:0;border-radius:18px}
  .exam-hero h2{font-size:27px}
  .exam-tips{gap:9px}
  .exam-tips div{padding:14px}
  .exam-bar{flex-wrap:wrap;gap:8px;padding:10px 12px}
  .exam-bar .exam-timer{font-size:18px}
  .exam-bar small{order:3;width:100%}
  .exam-submit{width:100%;margin-left:0}
  .exam-record{grid-template-columns:58px 1fr;gap:9px}
  .exam-record-time{grid-column:2;text-align:left}
  .study-catalog{margin-top:24px}
  .study-catalog-head{position:relative;padding-right:2px}
  .study-catalog-head .mindmap-note{display:none}
  .topic-menu-toggle{display:inline-flex;align-items:center;justify-content:center;min-width:92px;min-height:42px;padding:8px 12px;border-radius:10px;background:#eef2ff;color:var(--blue);font-size:11px;font-weight:700}
  .catalog-layout{position:relative}
  .catalog-scrim{display:none;position:fixed;inset:0;z-index:24;background:rgba(21,42,58,.28)}
  .catalog-scrim.is-open{display:block}
  .topic-list{position:fixed;left:0;top:0;bottom:0;z-index:25;width:min(84vw,320px);max-height:none!important;margin:0;padding:78px 14px 92px;display:block;overflow-y:auto;background:#fff;border:0;border-radius:0;box-shadow:8px 0 26px rgba(21,42,58,.16);transform:translateX(-105%);transition:transform .24s ease}
  .topic-list.is-open{transform:translateX(0)}
  .topic-item{width:100%;min-height:64px;margin-bottom:8px;padding:12px;background:#fff;border:1px solid var(--line);box-shadow:0 3px 10px rgba(21,42,58,.04)}
  .topic-item.selected{border-color:#cfd9ff;box-shadow:0 0 0 2px #e7edff}
  .topic-item strong{font-size:11px;line-height:1.45}
  .topic-item small{font-size:9px}
  .topic-detail{padding:17px}
  .topic-detail h3{font-size:19px}
  .box-diagram,.function-diagram,.forstep-diagram{flex-direction:column}
  .box-diagram>span,.function-diagram>span,.forstep-diagram>span{transform:rotate(90deg);align-self:center}
  .array-diagram{overflow-x:auto;justify-content:flex-start;padding-bottom:3px}
  .array-diagram span{flex:0 0 54px}
  .mindmap{min-height:650px;padding:14px}
  .mindmap-center{width:135px;height:82px}
  .mindmap-center b{font-size:15px}
  .toast{bottom:15px;max-width:calc(100vw - 30px);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
  .mobile-nav{position:fixed;display:flex;left:10px;right:10px;bottom:10px;z-index:30;min-height:62px;padding:6px 4px env(safe-area-inset-bottom);background:rgba(255,255,255,.97);border:1px solid #e4ebef;border-radius:18px;box-shadow:0 8px 26px rgba(21,42,58,.16);backdrop-filter:blur(14px)}
  .mobile-nav button{flex:1;min-width:0;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:3px;border-radius:12px;background:transparent;color:#8a99a2;min-height:50px}
  .mobile-nav button span{font-size:17px;line-height:1}
  .mobile-nav button small{font-size:10px;line-height:1.2}
  .mobile-nav button.active{color:var(--blue);background:#eef2ff;font-weight:700}
}

.next-point-btn{display:flex;align-items:center;justify-content:center;width:100%;min-height:44px;margin-top:14px;padding:10px 14px;border:1px solid #d6e0ff;border-radius:10px;background:#eef2ff;color:var(--blue);font-size:11px;font-weight:700}.next-point-btn:hover{background:#e2e9ff}.next-point-btn.complete{border-color:#dceee6;background:#f1fbf6;color:#4eaa89;cursor:default}