.theory-filters{display:grid;grid-template-columns:220px minmax(0,1fr);gap:18px;margin:28px 0 16px;max-width:810px}
.theory-filters label{display:grid;gap:9px;font-size:12px;color:var(--muted)}
.theory-filters input,.theory-filters select{width:100%;min-width:0;min-height:44px;padding:11px 14px;border:1px solid var(--line);border-radius:10px;background:var(--surface);color:var(--ink);font:inherit;font-size:14px}
.theory-count{font-size:12px;color:var(--muted);margin:0 0 28px}
.theory-group{margin:30px 0 38px}.theory-group-heading{display:flex;align-items:center;justify-content:space-between;gap:16px;margin-bottom:17px}.theory-group-heading h2{font-size:22px;font-weight:600;letter-spacing:-.4px}.theory-group-heading>span{font-size:12px;color:var(--muted)}
.theory-cards{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}.theory-card{display:flex;flex-direction:column;justify-content:space-between;gap:24px;padding:25px;border:1px solid var(--line);border-radius:16px;background:var(--surface);min-width:0;transition:border-color .15s,background .15s}.theory-card:hover{border-color:var(--blue);background:var(--blue-soft)}.theory-card h3{font-size:17px;line-height:1.5;font-weight:580;letter-spacing:-.3px;margin:0 0 10px;overflow-wrap:break-word}.theory-card p{font-size:12px;line-height:1.85;color:var(--muted);margin:0}.theory-card-footer{display:flex;align-items:center;justify-content:space-between;font-size:11px;color:var(--blue)}
.theory-reader{max-width:1290px;margin:0 auto;padding-bottom:70px}.theory-reader-toolbar{display:flex;justify-content:space-between;gap:18px;flex-wrap:wrap;margin:0 0 38px;font-size:12px}.theory-reading-layout{display:grid;grid-template-columns:minmax(0,760px) minmax(170px,210px);gap:45px;justify-content:center;align-items:start}.theory-prose{min-width:0}.theory-article-heading{margin-bottom:30px}.theory-article-heading h1{font-size:clamp(28px,2.8vw,40px);line-height:1.25;letter-spacing:-1px;margin:0 0 18px;overflow-wrap:break-word}.theory-reading-meta{display:flex;gap:18px;flex-wrap:wrap;color:var(--muted);font-size:12px!important;line-height:1.6!important;margin-bottom:19px!important}.theory-prose .theory-learning-goal{color:var(--muted);font-size:15px;line-height:1.8;margin:0;padding-bottom:26px;border-bottom:1px solid var(--line)}
.theory-prose>p{font-size:16px;line-height:1.95;margin:0 0 22px;overflow-wrap:break-word}.theory-prose>h2{font-size:23px;line-height:1.4;font-weight:600;letter-spacing:-.5px;margin:36px 0 17px;scroll-margin-top:26px}.theory-prose sub,.theory-prose sup{font-size:.72em}.theory-reaction{margin:27px 0;padding:21px 23px;background:var(--blue-soft);border-left:3px solid var(--blue);border-radius:0 10px 10px 0;min-width:0}.theory-equation{display:flex;align-items:center;flex-wrap:wrap;gap:2px 9px;font-size:19px;line-height:1.9;font-weight:500;min-width:0}.theory-term{display:inline-block;white-space:nowrap;max-width:100%;overflow-x:auto;vertical-align:middle;padding:2px 0}.theory-term .coefficient{margin-right:4px}.theory-operator{font-weight:400;color:var(--muted)}.theory-reaction .theory-conditions{color:var(--muted);font-size:12px;line-height:1.8;margin:13px 0 0}.theory-reaction figcaption{font-size:13px;line-height:1.8;margin:11px 0 0}
.theory-outline{position:sticky;top:32px;min-width:0;color:var(--muted)}.theory-outline summary{font-size:12px;font-weight:550;color:var(--ink);cursor:pointer;list-style:none;padding:0 0 15px}.theory-outline summary::-webkit-details-marker{display:none}.theory-outline nav{display:grid;gap:4px;border-left:1px solid var(--line);padding-left:13px}.theory-outline button{font:inherit;font-size:11px;line-height:1.8;text-align:left;color:var(--muted);padding:7px 0;border:0;background:none;cursor:pointer}.theory-outline button:hover{color:var(--blue)}
.theory-sources{margin:38px 0 0;border-top:1px solid var(--line);padding-top:22px}.theory-sources summary{font-size:13px;font-weight:550;cursor:pointer;line-height:1.8}.theory-sources ol{padding-left:20px;margin-top:16px}.theory-sources li{font-size:12px;line-height:1.8;margin:10px 0;overflow-wrap:anywhere}.theory-sources a{color:var(--blue);text-decoration:underline;text-underline-offset:3px}.theory-reading-end{margin-top:36px;padding:25px 0 0;border-top:1px solid var(--line)}.theory-reading-end h2{font-size:21px;font-weight:600;margin:0 0 10px;letter-spacing:-.4px}.theory-reading-end p{font-size:13px;line-height:1.8;color:var(--muted);margin:0 0 20px}.theory-end-actions{display:flex;flex-wrap:wrap;gap:12px}.theory-end-actions .btn{font-size:12px}.theory-gateway{border-color:var(--line)}.topic-mode-choices{gap:10px}.study-heading-actions{display:flex;align-items:center;gap:10px;flex-wrap:wrap}.study-heading-actions .btn{font-size:12px;white-space:nowrap}.practice-header-actions{display:flex;align-items:center;gap:22px;flex:none}
@media(max-width:1200px){.theory-reading-layout{display:flex;flex-direction:column;max-width:760px;margin:auto;gap:25px}.theory-outline{order:-1;position:static;width:100%;border:1px solid var(--line);border-radius:10px;padding:14px 17px;background:var(--surface)}.theory-outline summary{padding:0;font-size:13px;list-style:disclosure-closed}.theory-outline details[open] summary{list-style:disclosure-open;margin-bottom:12px}.theory-outline nav{margin-top:6px}.theory-outline button{font-size:12px}.theory-reader-toolbar{max-width:760px;margin:0 auto 26px}.study-heading-actions{margin-top:20px}.theory-library>.page-heading>.btn{margin-top:18px}}
@media(max-width:700px){.theory-filters{grid-template-columns:1fr;gap:14px;margin:23px 0 16px}.theory-cards{grid-template-columns:1fr;gap:12px}.theory-card{padding:20px;gap:20px}.theory-card h3{font-size:16px}.theory-group-heading h2{font-size:19px}.theory-group-heading>span{font-size:10px}.theory-reader-toolbar{font-size:11px;gap:12px;margin-bottom:24px}.theory-prose>p{font-size:15px;line-height:1.9;margin-bottom:20px}.theory-prose>h2{font-size:21px;margin-top:30px}.theory-prose .theory-learning-goal{font-size:13px;padding-bottom:22px}.theory-reading-meta{font-size:11px!important}.theory-reaction{padding:17px 15px;margin:24px 0}.theory-equation{font-size:17px;column-gap:7px}.theory-reaction figcaption{font-size:12px}.theory-reaction .theory-conditions{font-size:11px}.theory-end-actions{flex-direction:column;align-items:stretch}.theory-reader{padding-bottom:45px}.study-heading-actions{display:grid;grid-template-columns:1fr;width:100%}.study-heading-actions .btn{width:100%;font-size:12px}.practice-header-actions{gap:13px}.practice-title{min-width:0}.practice-title h1{max-width:130px}.practice-header-actions .text-link{font-size:10px}.sidebar .utility-nav{grid-template-columns:1fr}.theory-library>.page-heading>.btn{width:100%}}
@media(prefers-reduced-motion:reduce){.theory-card{transition:none}}