/* Article content stays visible; practice and references use native disclosures. */
@media screen {
  .concept-library,.concept-post{--ink:#1c2b4b;--text:#303747;--muted:#737b8b;--line:#e7eaf0;--surface:#f6f7fa;background:#fff}
  :is(.concept-library,.concept-post) .site-header{height:76px}
  :is(.concept-library,.concept-post) .learning-nav[aria-current=page]{color:var(--ink);text-decoration:underline;text-underline-offset:9px;text-decoration-thickness:2px}
  :is(.concept-library,.concept-post) .breadcrumbs{gap:9px;font-size:11px;padding-top:24px;flex-wrap:wrap}
  :is(.concept-library,.concept-post) .eyebrow{font-size:12px;letter-spacing:0;font-weight:500;color:var(--muted)}
  .concept-post .concept-article{max-width:780px}
  .concept-post .lesson-hero{display:block;max-width:none;padding:32px 0 26px}
  .concept-post .lesson-hero>.eyebrow{display:flex;align-items:center;gap:8px}
  .concept-post .lesson-hero h1{font-size:clamp(28px,3.2vw,36px);line-height:1.45;letter-spacing:-.045em;margin-top:12px;max-width:none;word-break:keep-all;overflow-wrap:break-word}
  .concept-explanation{padding-bottom:34px;border-bottom:1px solid var(--line);scroll-margin-top:24px}
  .concept-post .concept-explanation>.lesson-intro{font-size:17px;line-height:1.95;color:#556075;margin:0 0 30px}
  .concept-explanation .comparison-heading{font-size:21px;font-weight:650;letter-spacing:-.03em;margin:32px 0 18px}
  .concept-post .lesson-disclosure{border:0;border-bottom:1px solid var(--line);padding:0;scroll-margin-top:24px}
  .lesson-disclosure>summary{padding:20px 2px;gap:16px}
  .lesson-disclosure>summary h2{font-size:15px;line-height:1.6;font-weight:600;letter-spacing:-.02em;margin:0}
  .lesson-disclosure>summary h2>span{font-size:11px;color:var(--muted);font-weight:400;margin-left:8px;white-space:nowrap}
  .lesson-disclosure>summary::after{font-size:20px;color:#8b93a1;line-height:1}
  :is(.concept-post,.concept-library) details>summary::after{content:'+'}
  :is(.concept-post,.concept-library) details[open]>summary::after{content:'−'}
  .lesson-disclosure[open]>summary{padding-bottom:18px}
  .lesson-disclosure[open]>summary h2{color:#2e4777}
  .disclosure-body{padding:0 2px 28px}
  .concept-post .disclosure-body>p{padding:0;margin:0 0 14px;font-size:14px;line-height:1.95;color:#616b7d}
  .concept-post .term-definitions{grid-template-columns:1fr;gap:28px;margin:28px 0}
  .concept-post .term-definitions h2{font-size:22px;font-weight:650;letter-spacing:-.03em}
  .concept-post .term-definitions p{font-size:15px;line-height:1.95;color:#556075;margin-top:9px}
  .concept-post .term-definitions .term-caption{font-size:12px;color:#8791a3;margin-top:5px}
  .concept-post .comparison-scroll{border-radius:8px;background:#fff}
  .concept-post .comparison-table{font-size:13px;line-height:1.85}
  .concept-post .comparison-table th,.concept-post .comparison-table td{padding:15px}
  .concept-post .comparison-table thead{background:#f2f4f8}
  .concept-post .comparison-table tbody th{background:#fafbfc;color:#69758a;font-size:12px}
  .concept-post .takeaway{border-color:#9ba9c2;background:#f5f7fb;padding:18px 20px;border-radius:0 6px 6px 0;margin-top:22px}
  .concept-post .takeaway h3{font-size:16px;font-weight:650;line-height:1.75;margin:0}
  .concept-post .takeaway p{padding:0;font-size:14px;line-height:1.95;margin:8px 0 0;color:#616b7d}
  .concept-post .disclosure-body>.content-notice{background:#f5f6f9;padding:12px 14px;border-radius:6px;font-size:11px;line-height:1.9;margin:0 0 20px}
  .concept-post .source-links{font-size:10px;line-height:1.9;gap:4px 12px}
  .concept-post .quiz-progress{margin:16px 0 20px;font-size:11px;gap:18px}
  .concept-post progress{accent-color:#3e5688}
  .concept-post .question-list{gap:16px}
  .concept-post .question-card{border-color:var(--line);border-radius:8px;padding:22px;background:#fff}
  .concept-post .question-meta{font-size:10px;line-height:1.8;flex-wrap:wrap}
  .concept-post .question-card h3{font-size:16px;line-height:1.9}
  .concept-post .answer-options{margin-top:16px}
  .concept-post .answer-options button{background:#f7f8fa;border-color:#e1e5ec;border-radius:6px;min-height:48px}
  .concept-post .answer-options button:hover:not(:disabled){background:#eef2fa;border-color:#93a5c6}
  .concept-post .answer-options button[aria-pressed=true]{background:#edf2fc;border-color:#8c9fc5;color:#344f81}
  .concept-post .question-card[data-outcome=incorrect] button[aria-pressed=true]{background:#fbf0e9;border-color:#b87955;color:#8a472a}
  .concept-post .answer-feedback{color:#344f81}
  .concept-post .question-card[data-outcome=incorrect] .answer-feedback{color:#8a472a}
  .concept-post .explanation p{font-size:13px;line-height:1.95;color:#616b7d}
  .concept-post .explanation .correct-answer{color:var(--ink)}
  .concept-post .explanation .remember{background:#f2f4f8;padding:12px 14px}
  .concept-post .quiz-result{background:#f2f5fb;border-color:#dce4f2}
  .concept-post .concept-exam-list{gap:0;margin:16px 0 0}
  .concept-post .concept-exam-list li{border:0;border-bottom:1px solid var(--line);border-radius:0;background:transparent;padding:20px 0}
  .concept-post .concept-exam-list li:first-child{padding-top:0}
  .concept-post .concept-exam-list li:last-child{border-bottom:0;padding-bottom:0}
  .concept-post .concept-exam-list li>.eyebrow{font-size:10px;color:#778299}
  .concept-post .concept-exam-list blockquote{border-left:2px solid #b3bfd5;padding-left:16px;font-size:14px;line-height:1.95;color:#46536c}
  .concept-post .concept-exam-list .exam-context{padding:0;font-size:12px;line-height:1.85}
  .concept-post .concept-exam-list .exam-passage{background:#f5f6f9;font-size:13px;line-height:1.95;padding:14px}
  .concept-post .sources ul{margin:0 0 20px}
  .concept-post .sources li{padding:14px 0}
  .concept-post .sources li p{padding:0;font-size:12px;line-height:1.9;margin:5px 0 0;color:#737b8b}
  .concept-post .sources li a{font-size:13px;line-height:1.9}
  .concept-post .related-lessons{padding:0 2px 20px}
  .concept-post .related-lessons ul{list-style:none;padding:0;margin:0;font-size:13px;line-height:1.9}
  .concept-post .related-lessons li a{display:block;padding:10px 0}
  .concept-post .related-lessons li a:hover{text-decoration:underline;text-underline-offset:4px}
  .article-back{display:inline-block;font-size:12px;color:var(--muted);margin:24px 0 40px}
  .concept-post .site-footer{max-width:780px}
  :is(.concept-library,.concept-post) .site-footer{padding-block:20px}
  :is(.concept-library,.concept-post) .footer-top .brand{font-size:14px}
  :is(.concept-library,.concept-post) .footer-top{margin-bottom:12px}
  :is(.concept-library,.concept-post) .footer-links{font-size:11px}
  :is(.concept-library,.concept-post) .site-footer p,:is(.concept-library,.concept-post) .site-footer small{font-size:10px;line-height:1.8}

  /* The catalog exposes titles first. Summaries are available on hover and keyboard focus. */
  .concept-library .learn-hero{display:flex;align-items:baseline;gap:20px;flex-wrap:wrap;padding:32px 0 26px}
  .concept-library .learn-hero h1{font-size:32px;line-height:1.45;letter-spacing:-.045em;margin:0}
  .concept-library .lesson-meta{font-size:11px;margin:0}
  .concept-search{display:flex;align-items:center;gap:12px;border:1px solid #dfe4ed;border-radius:8px;background:#fff;padding:0 16px;min-height:50px;margin:0 0 18px}
  .concept-search:focus-within{border-color:#8c9fc4;box-shadow:0 0 0 3px #f0f3fa}
  .concept-search label{display:flex;align-items:center;gap:10px;flex:1;min-width:0;color:#8892a5}
  .concept-search input{min-width:0;width:100%;height:48px;background:transparent;border:0;outline:0;font:inherit;font-size:13px;color:var(--ink)}
  .concept-search input::placeholder{color:#7c8698;opacity:1}
  .concept-search .text-button{font-size:11px;flex-shrink:0;min-height:40px}
  .concept-library .concept-subject-tabs{gap:6px;padding-bottom:20px}
  .concept-library .concept-subject-tabs a{font-size:12px;padding:6px 11px;border-radius:5px;border-color:transparent;background:transparent;min-height:34px;display:inline-flex;align-items:center}
  .concept-library .concept-subject-tabs a:hover{background:#f5f6f9}
  .concept-library .concept-subject-tabs a[aria-current=page]{background:#edf1f8;color:#314a78;border-color:transparent}
  .concept-library .concept-subject-section{padding:28px 0 0}
  .concept-library .catalog-heading{border-top:0;align-items:baseline;padding:0 0 14px;gap:12px}
  .concept-library .catalog-heading h2{font-size:18px;letter-spacing:-.03em}
  .concept-library .catalog-heading .text-link{margin:0;font-size:11px;white-space:nowrap}
  .concept-library .concept-catalog{grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;padding:0}
  .concept-library .concept-card{position:relative;padding:20px;border:1px solid var(--line);border-radius:8px;background:#fff;transition:border-color .15s,background .15s;overflow:visible}
  .concept-library .concept-card:hover{background:#fafbfe;border-color:#a7b5cf;z-index:2}
  .concept-library .concept-card:focus-visible{z-index:3}
  .concept-library .concept-card-number{display:none}
  .concept-card-subject{display:block;font-size:10px;color:#74829b;font-weight:500;margin-bottom:6px}
  .concept-library .concept-card h3{font-size:16px;line-height:1.65;letter-spacing:-.025em;margin:0}
  .concept-library .concept-card>div{display:flex;flex-direction:column;min-width:0;flex:1}
  .concept-library .concept-card-meta{margin-top:auto;padding-top:16px;font-size:10px;font-weight:400;display:flex;justify-content:space-between;gap:12px;color:#8891a1}
  .concept-library .concept-card-meta>span{font-size:14px;color:#60749a;line-height:1.2}
  .concept-library .concept-card .concept-card-preview{position:absolute;bottom:calc(100% + 8px);left:0;width:min(320px,100%);margin:0;padding:14px 16px;background:#28364f;color:#fff;border-radius:7px;box-shadow:0 8px 24px #1c2b4b1a;font-size:12px;line-height:1.9;visibility:hidden;z-index:4;font-weight:400;word-break:keep-all}
  .concept-library .concept-card .concept-card-preview::after{content:'';position:absolute;top:100%;left:22px;border:6px solid transparent;border-top-color:#28364f}
  .concept-library .concept-card .concept-card-preview::before{content:'';position:absolute;top:100%;left:0;width:100%;height:10px}
  .concept-library .concept-card:focus-visible:not(.preview-dismissed) .concept-card-preview{visibility:visible}
  .concept-library .concept-guide{background:transparent;border:0;border-top:1px solid var(--line);border-bottom:1px solid var(--line);border-radius:0;padding:0;margin:32px 0}
  .concept-library .concept-guide summary{font-size:13px;padding:18px 0;color:#737d90}
  .concept-library .concept-guide>div{padding-bottom:20px}
  .concept-library .concept-guide ol{font-size:13px;line-height:2}
  .concept-library .concept-guide p{padding:0;font-size:13px;line-height:1.9;margin:0 0 12px}
  .concept-library .concept-guide .text-link{margin-right:20px;font-size:12px}
  .concept-library .subject-list-heading{padding-top:26px}
  .concept-library .subject-list-heading>span{font-size:11px}
  .concept-subject [data-concept-browse]>.concept-catalog{grid-template-columns:1fr;gap:0;border-top:1px solid var(--line)}
  .concept-subject [data-concept-browse]>.concept-catalog .concept-card{display:grid;grid-template-columns:28px minmax(0,1fr);gap:14px;border:0;border-bottom:1px solid var(--line);border-radius:0;padding:18px 12px;background:transparent}
  .concept-subject [data-concept-browse] .concept-card:hover{background:#f8f9fc}
  .concept-subject [data-concept-browse] .concept-card-number{display:block;padding-top:2px;font-size:11px;color:#929bab}
  .concept-subject [data-concept-browse] .concept-card>div{flex-direction:row;align-items:baseline;justify-content:space-between;gap:16px}
  .concept-subject [data-concept-browse] .concept-card h3{font-size:16px}
  .concept-subject [data-concept-browse] .concept-card-meta{padding:0;margin:0;white-space:nowrap}
  .concept-library .concept-pagination{margin:24px 0 32px;gap:6px}
  .concept-library .concept-pagination a{border-color:transparent;min-width:38px;min-height:38px;padding:8px 12px;text-align:center;font-size:12px}
  .concept-library .concept-pagination a[aria-current=page]{background:#edf1f8;color:#314a78}
  .concept-search-results{padding-top:26px;padding-bottom:8px}
  .concept-search-results .catalog-heading{align-items:center}
  .concept-search-results [role=status]{font-size:12px;color:var(--muted);overflow-wrap:anywhere}
  .concept-search-results>.button{display:flex;margin:20px auto 8px;font-size:12px}
  .search-empty{grid-column:1/-1;color:var(--muted);font-size:13px;padding:28px 0 36px}
}
@media screen and (hover:hover) {
  .concept-library .concept-card:hover:not(.preview-dismissed) .concept-card-preview{visibility:visible}
}
@media screen and (max-width:980px) {
  .concept-library .concept-catalog{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@media screen and (max-width:700px) {
  .concept-post .lesson-hero{padding:26px 0 22px}
  .concept-post .lesson-hero h1{font-size:28px;line-height:1.5}
  .concept-post .concept-explanation>.lesson-intro{font-size:15px;margin-bottom:26px}
  .concept-post .term-definitions h2{font-size:20px}
  .concept-post .term-definitions p{font-size:14px}
  .concept-post .term-definitions .term-caption{font-size:11px}
  .concept-explanation .comparison-heading{font-size:19px}
  .lesson-disclosure>summary{padding:18px 0}
  .lesson-disclosure>summary h2{font-size:14px}
  .lesson-disclosure>summary h2>span{font-size:10px;margin-left:6px}
  .concept-post .question-card{padding:18px}
  .concept-post .question-card h3{font-size:15px}
  .concept-post .comparison-table th,.concept-post .comparison-table td{padding:12px}
  .concept-library .learn-hero{display:block;padding:26px 0 22px}
  .concept-library .learn-hero h1{font-size:28px}
  .concept-library .lesson-meta{font-size:11px;margin-top:9px}
  .concept-search{padding-inline:12px;gap:8px}
  .concept-search label{gap:8px}
  .concept-search input{font-size:12px}
  .concept-library .concept-subject-tabs{gap:4px;padding-bottom:16px}
  .concept-library .concept-subject-tabs a{font-size:11px;padding:6px 9px}
  .concept-library .concept-subject-section{padding-top:24px}
  .concept-library .catalog-heading h2{font-size:17px}
  .concept-library .concept-catalog{grid-template-columns:1fr;gap:10px}
  .concept-library .concept-card{padding:17px 18px}
  .concept-library .concept-card-meta{padding-top:10px}
  .concept-subject [data-concept-browse]>.concept-catalog .concept-card{grid-template-columns:20px minmax(0,1fr);gap:10px;padding:16px 0}
  .concept-subject [data-concept-browse] .concept-card>div{flex-direction:column;align-items:stretch;gap:6px}
  .concept-subject [data-concept-browse] .concept-card h3{font-size:16px}
}
@media screen and (max-width:360px) {
  :is(.concept-library,.concept-post) .site-header{flex-wrap:wrap;align-content:center;justify-content:flex-start;gap:8px;height:auto;min-height:88px;padding-block:12px}
  :is(.concept-library,.concept-post) .site-header nav{width:100%;gap:18px;justify-content:space-between;font-size:11px}
  :is(.concept-library,.concept-post) .site-header .brand{font-size:14px}
  .concept-post .lesson-hero h1{font-size:25px}
  .concept-search svg{display:none}
}
@media (prefers-reduced-motion:reduce) {
  .concept-library .concept-card{transition:none}
}
@media print {
  .concept-post .lesson-hero{display:block}
  .concept-search,.concept-search-results,.concept-card-preview,.article-back{display:none!important}
  [data-concept-browse]{display:block!important}
  .lesson-disclosure>summary{display:none}
  .lesson-disclosure{border:0;margin-block:20px}
}