/* Global header and footer */
.site-header { position: sticky; top: 0; z-index: 30; background: var(--surface); border-top: 3px solid var(--primary); border-bottom: 1px solid var(--border); }
.header-inner { min-height: 76px; display: flex; align-items: center; justify-content: space-between; gap: 30px; }
.brand { display: inline-flex; align-items: center; gap: var(--space-3); white-space: nowrap; color: var(--primary); font-size: 1.1rem; letter-spacing: -.03em; font-weight: 800; }
.brand-mark { display: inline-flex; width: 43px; height: 43px; flex: 0 0 auto; }
.footer-dot { color: var(--amber); }
.site-nav { position: relative; display: flex; align-items: center; gap: 5px; overflow: clip; overflow-clip-margin: 6px; }
.site-nav a { position: relative; background: transparent; display: inline-flex; align-items: center; justify-content: center; min-height: 44px; padding: 10px var(--space-4); color: var(--muted); font-size: .88rem; font-weight: 620; border-bottom: 2px solid transparent; transition: background var(--interaction), color var(--interaction); }
.site-nav a:hover { color: var(--primary); }
.site-nav a[aria-current="page"] { color: var(--primary); border-bottom-color: var(--primary); font-weight: 750; }
.site-footer { border-top: 1px solid var(--border); background: var(--surface); }
.footer-inner { display: flex; justify-content: space-between; gap: var(--space-6); padding-block: var(--space-8) var(--space-6); }
.footer-title { color: var(--primary); font-weight: 800; font-size: 1.2rem; letter-spacing: -.05em; margin-bottom: 10px; }
.footer-inner p { color: var(--muted); font-size: .88rem; margin: 0 0 7px; }
.footer-inner p.footer-disclaimer { max-width: 470px; font-size: .76rem; }
.footer-links { display: grid; grid-template-columns: repeat(2, minmax(108px, 1fr)); align-content: start; gap: 11px 22px; font-size: .84rem; font-weight: 620; }
.footer-links a { display: inline-flex; align-items: center; min-height: 44px; }
.footer-links a:hover { color: var(--primary); text-decoration: underline; }
.footer-bottom { display: flex; justify-content: space-between; gap: 20px; padding-block: 17px var(--space-6); color: var(--muted); font-size: .76rem; border-top: 1px solid var(--border-light); }
/* Homepage hero */
.hero { padding-block: var(--space-8); background: var(--background); border-bottom: 1px solid var(--border-light); }
.hero-grid { display: grid; grid-template-columns: minmax(0, 1.5fr) minmax(260px, .85fr); gap: clamp(var(--space-8), 5vw, 68px); align-items: center; }
.hero h1 { font-size: clamp(2.1rem, 3.6vw, 3rem); line-height: 1.15; letter-spacing: -.05em; color: var(--primary); margin: 14px 0 14px; }
.hero h1 em, .about-intro h1 em, .not-found-section h1 em { font-weight: 530; }
.hero-subtitle { color: var(--muted); max-width: 590px; line-height: 1.6; font-size: .94rem; margin-bottom: 20px; }
.hero-search { display: flex; align-items: center; gap: 10px; max-width: 595px; min-height: 58px; padding: 5px 5px 5px 15px; background: white; border: 1px solid var(--primary); border-radius: var(--radius); }
.hero-search > .icon { color: var(--secondary); width: 22px; height: 22px; }
.hero-search input { background: transparent; outline: none; border: 0; flex: 1; min-width: 0; font-size: .94rem; color: var(--primary); }
.hero-search:focus-within { outline: 3px solid var(--focus); outline-offset: 3px; }
.hero-search input::placeholder { color: var(--muted); }
.hero-search .btn { padding-inline: 21px; min-height: var(--space-12); }
.hero-helper { color: var(--primary); font-size: .79rem; margin: var(--space-3) 0 0; }
.hero-aside { position: relative; overflow: hidden; background: var(--primary); color: white; border-radius: var(--radius); padding: 20px; }
.hero-aside > * { position: relative; }
.hero-study-title { margin-block: 6px 10px; font-size: 1.25rem; font-weight: 700; line-height: 1.25; letter-spacing: -.03em; }
.hero-study-title span { color: var(--amber); }
.study-steps { display: grid; gap: 2px; }
.study-steps > div { display: flex; align-items: center; gap: 13px; border-top: 1px solid rgba(255,255,255,.2); padding: 8px 0; }
.study-steps > div:last-child { border-bottom: 1px solid rgba(255,255,255,.2); }
.study-steps span { font-size: .71rem; font-weight: 700; letter-spacing: .07em; color: var(--amber); }
.study-steps .icon { color: #D8E6F1; width: 18px; height: 18px; }
.study-steps p { margin: 0; font-size: .84rem; }
/* Home sections */
.section { padding-block: 28px; }
.section-years { background: var(--surface); border-bottom: 1px solid var(--border-light); }
.section-list { padding-block: var(--space-8) 40px; }
.section-top { display: flex; align-items: end; justify-content: space-between; gap: 22px; margin-bottom: 20px; }
.section-top h2 { color: var(--primary); margin: 9px 0 0; }
.section-description { margin: var(--space-2) 0 0; font-size: .9rem; color: var(--muted); }
.year-list { display: flex; flex-wrap: wrap; gap: 10px; min-height: 42px; }
.year-chip { display: inline-grid; place-items: center; min-width: 70px; min-height: 44px; padding: var(--space-2) 14px; background: white; border: 1px solid var(--border); border-radius: var(--radius-sm); color: var(--primary); font-family: var(--font-mono); font-size: .88rem; font-weight: 700; }
.year-chip:hover { background: var(--primary); color: white; border-color: var(--primary); }
.results-label, .sort-label { display: inline-flex; align-items: center; gap: var(--space-2); font-size: .78rem; color: var(--muted); white-space: nowrap; }
.section-end { display: flex; flex-wrap: wrap; gap: var(--space-3); justify-content: center; margin-top: var(--space-8); }
.purpose-band { background: var(--primary); padding-block: var(--space-8); }
.purpose-band .btn:focus-visible { outline-color: white; }
.purpose-inner { display: flex; justify-content: space-between; align-items: center; gap: 20px; }
.purpose-inner .eyebrow { color: var(--amber); }
.purpose-inner h2 { color: white; font-size: 1.9rem; margin: 9px 0 var(--space-2); }
.purpose-inner p { color: #D8E6F1; margin: 0; font-size: .91rem; }
/* Archives */
.archive-intro { border-bottom: 1px solid var(--border-light); padding: 28px 0 var(--space-6); }
.archive-intro h1 { margin: var(--space-2) 0 var(--space-2); font-size: clamp(2rem, 4vw, 2.8rem); color: var(--primary); letter-spacing: -.045em; }
.archive-intro p { margin-bottom: 0; color: var(--muted); max-width: 680px; font-size: 1rem; }
.archive-section { padding: var(--space-6) 0 56px; }
.filters-card { background: transparent; border: 0; border-bottom: 1px solid var(--border); border-radius: 0; padding: 0 0 24px; }
.filter-search label, .filter-field label { display: block; color: var(--primary); font-weight: 710; font-size: .8rem; margin-bottom: var(--space-2); }
.filter-search-input { position: relative; display: flex; align-items: center; gap: 10px; border: 1px solid var(--border); background: var(--surface); border-radius: var(--radius-sm); min-height: var(--space-12); padding: 0 13px; }
.filter-search-input .icon { color: var(--secondary); width: 19px; height: 19px; }
.filter-search-input:focus-within { outline: 3px solid var(--focus); outline-offset: 3px; }
.filter-search-input input { width: 100%; border: none; outline: none; background: transparent; min-height: 46px; color: var(--primary); font-size: .91rem; }
.filter-search-input input::placeholder { color: var(--muted); }
.filters-row { display: flex; flex-wrap: wrap; align-items: end; gap: 13px; margin-top: 17px; }
.filter-field { flex: 1 1 145px; min-width: 120px; }
.filter-field select { display: block; width: 100%; min-height: 46px; border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface); color: var(--text); padding: 9px 30px 9px var(--space-3); font-size: .9rem; cursor: pointer; }
.filter-field select:focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; }
.reset-button { display: inline-flex; align-items: center; justify-content: center; gap: var(--space-2); padding: 10px 10px; background: transparent; border: 0; border-radius: var(--radius-sm); color: var(--primary); font-weight: 690; min-height: 46px; font-size: .81rem; }
.reset-button:hover { background: var(--accent); }
.reset-button .icon { width: var(--space-4); height: var(--space-4); }
.archive-result-bar { margin: 33px 0 20px; display: flex; align-items: end; justify-content: space-between; gap: 18px; }
.archive-result-bar h2 { font-size: 1.45rem; color: var(--primary); margin: 0 0 3px; }
.archive-result-bar p { color: var(--muted); margin: 0; font-size: .83rem; }
.sort-label .icon { width: var(--space-4); height: var(--space-4); }
/* Archive card components */
.paper-list { display: grid; grid-template-columns: 1fr; gap: 0; border-top: 1px solid var(--border); }
.paper-list > .empty-state, .paper-list > .loading-placeholder { grid-column: 1 / -1; }
.paper-card { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr); align-items: center; gap: var(--space-6); min-width: 0; padding: 22px var(--space-4); background: var(--surface); border-bottom: 1px solid var(--border); border-left: 3px solid transparent; transition: background var(--interaction), border-color var(--interaction); }
.paper-card:hover { background: #F8FAFC; border-left-color: var(--primary); }
.paper-card-top { display: flex; gap: 10px; justify-content: space-between; align-items: start; }
.paper-card-heading { min-width: 0; }
.paper-card .eyebrow { font-size: .65rem; letter-spacing: .09em; margin: 0 0 6px; }
.paper-title { font-size: 1.12rem; color: var(--primary); margin: 0 0 10px; overflow-wrap: anywhere; line-height: 1.4; }
.paper-title-link:hover { text-decoration: underline; text-underline-offset: 3px; }
.paper-meta { display: flex; align-items: center; flex-wrap: wrap; gap: 7px; }
.tag { display: inline-flex; padding: 2px 7px; border-radius: var(--radius-sm); background: var(--accent); border: 1px solid var(--border-light); color: var(--muted); font-weight: 560; font-size: .75rem; line-height: 1.5; }
.tag.subject-tag { background: var(--accent); color: var(--primary); }
.tag.subtle-tag { background: var(--surface); }
.card-arrow { display: inline-flex; justify-content: center; align-items: center; width: 44px; height: 44px; flex: 0 0 auto; border: 1px solid var(--border); border-radius: var(--radius-sm); color: var(--primary); }
.card-arrow .icon { width: 18px; height: 18px; }
.card-arrow:hover { background: var(--primary); color: #fff; }
.resources-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; margin: 0; padding: 0; }
.resource-block { display: flex; flex-direction: column; gap: var(--space-2); border-left: 1px solid var(--border); padding-left: 18px; min-width: 0; }
.resource-heading { display: flex; align-items: center; gap: 7px; color: var(--text); font-size: .8rem; font-weight: 650; }
.resource-heading .icon { width: 15px; height: 15px; }
.resource-actions { display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-1) var(--space-2); min-height: 44px; }
.action-link { display: inline-flex; align-items: center; gap: 5px; color: var(--primary); font-size: .8rem; font-weight: 700; min-height: 44px; padding: 7px var(--space-2); border-radius: var(--radius-sm); }
.action-link:hover { background: var(--accent); text-decoration: underline; text-underline-offset: 3px; }
.action-link .icon { width: 15px; height: 15px; }
.not-available { color: var(--muted); font-size: .8rem; }
.empty-state { display: flex; flex-direction: column; align-items: center; text-align: center; justify-content: center; gap: var(--space-3); min-height: 252px; padding: 35px 20px; border: 0; border-top: 1px solid var(--border-light); background: transparent; border-radius: 0; }
.empty-icon { width: 55px; height: 55px; border-radius: var(--radius); background: var(--border-light); display: grid; place-items: center; color: var(--primary); }
.empty-icon .icon { width: 26px; height: 26px; }
.empty-state h3 { color: var(--primary); font-size: 1.2rem; margin: 2px 0 0; }
.empty-state p { max-width: 425px; color: var(--muted); font-size: .89rem; margin: 0; }
.empty-state .btn { margin-top: var(--space-1); }
/* Viewer */
.viewer-section { padding: 35px 0 90px; }
.viewer-breadcrumb { min-height: 35px; margin-bottom: 22px; }
.back-link { color: var(--muted); display: inline-flex; align-items: center; gap: var(--space-2); font-size: .84rem; font-weight: 720; min-height: 44px; }
.back-link .icon { width: 17px; height: 17px; }
.viewer-heading h1 { font-size: clamp(2rem, 3.8vw, 3.1rem); margin: 9px 0 9px; color: var(--primary); }
.viewer-heading p { color: var(--muted); font-size: .92rem; margin: 0; }
.viewer-tabs { margin-top: 29px; display: flex; align-items: stretch; gap: 9px; border-bottom: 1px solid var(--border); overflow-x: auto; scrollbar-width: thin; }
.viewer-tab { flex: 0 0 auto; min-height: 50px; border: 0; border-bottom: 3px solid transparent; background: transparent; padding: var(--space-3) 17px; font-size: .88rem; font-weight: 690; color: var(--muted); }
.viewer-tab:hover { color: var(--primary); background: var(--accent); }
.viewer-tab[aria-selected="true"] { color: var(--primary); background: var(--accent); border-bottom-color: var(--primary); }
.viewer-content { background: var(--surface); border: 1px solid var(--border); border-top: 0; border-radius: 0 0 var(--radius) var(--radius); min-height: 330px; padding: var(--space-6); }
.viewer-panel { min-width: 0; }
.viewer-panel-header { display: flex; justify-content: space-between; align-items: center; gap: 20px; margin-bottom: 21px; }
.panel-title { color: var(--primary); font-size: 1.25rem; margin: 0 0 5px; }
.panel-subtitle { color: var(--muted); font-size: .84rem; margin: 0; }
.viewer-actions { display: flex; flex-wrap: wrap; gap: 9px; }
.pdf-shell { border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; background: var(--accent); }
.pdf-bar { height: 41px; display: flex; align-items: center; gap: 9px; border-bottom: 1px solid var(--border); color: var(--muted); font-size: .75rem; font-weight: 710; background: var(--accent); padding: 0 14px; }
.pdf-bar .icon { width: var(--space-4); height: var(--space-4); }
.pdf-frame { border: none; display: block; width: 100%; height: clamp(460px, 73vh, 900px); background: var(--accent); }
.pdf-hint { display: flex; align-items: start; gap: 7px; font-size: .78rem; color: var(--muted); line-height: 1.6; margin: 15px 0 0; }
.pdf-hint .icon { width: 17px; height: 17px; margin-top: 2px; }
.resource-unavailable { display: flex; flex-direction: column; gap: var(--space-3); min-height: 310px; align-items: center; justify-content: center; text-align: center; background: var(--accent); border: 1px dashed var(--border-light); border-radius: var(--radius); padding: var(--space-6); }
.resource-unavailable h2, .resource-unavailable h3 { color: var(--primary); font-size: 1.18rem; margin: 0; }
.resource-unavailable p { max-width: 455px; color: var(--muted); font-size: .86rem; margin: 0; }
.resource-unavailable .btn { margin-top: 6px; }
/* Mapped video selection */
.video-intro { margin-bottom: 22px; }
.video-layout { display: grid; grid-template-columns: minmax(215px, .73fr) minmax(0, 1.27fr); gap: 22px; align-items: start; }
.video-list { display: flex; flex-direction: column; gap: 7px; max-height: 650px; overflow: auto; padding-right: 3px; }
.video-group-label { color: var(--muted); letter-spacing: .09em; font-size: .74rem; text-transform: uppercase; font-weight: 770; margin: 15px 0 6px; }
.video-group-label:first-child { margin-top: 0; }
.video-item { display: flex; align-items: center; gap: 10px; min-width: 0; border: 1px solid var(--border); background: #fff; padding: 11px 10px; border-radius: var(--radius-sm); text-align: left; color: var(--primary); }
.video-item:hover, .video-item[aria-pressed="true"] { background: var(--border-light); border-color: var(--border); }
.video-item > .icon:first-child { color: var(--secondary); width: 19px; height: 19px; }
.video-item > .icon:last-child { color: var(--muted); width: var(--space-4); height: var(--space-4); }
.video-item-text { display: flex; flex-direction: column; flex: 1 1 auto; min-width: 0; }
.video-item-text strong { font-size: .83rem; }
.video-item-text small { color: var(--muted); font-size: .73rem; }
.video-player-block { min-width: 0; }
.video-player-area { background: var(--primary); border-radius: var(--radius); overflow: hidden; }
.player-placeholder { aspect-ratio: 16 / 9; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: var(--space-3); padding: 15px; color: #D8E6F1; text-align: center; }
.player-placeholder .icon { width: 45px; height: 45px; }
.player-placeholder p { font-size: .85rem; margin: 0; }
.youtube-embed { aspect-ratio: 16 / 9; }
.video-frame { display: block; width: 100%; height: 100%; border: 0; }
.video-player-details { margin: 15px 0 var(--space-3); }
.video-player-title { color: var(--primary); font-size: .96rem; font-weight: 750; margin: 0 0 3px; }
.video-player-description { color: var(--muted); font-size: .78rem; margin: 0; }
.related-playlists { margin-top: 25px; padding: 18px; border-radius: var(--radius); background: var(--accent); }
.related-playlists h3 { font-size: .99rem; color: var(--primary); margin: 0 0 7px; }
.related-playlists p { font-size: .82rem; color: var(--muted); margin: 0 0 9px; }
.playlist-links { display: flex; flex-wrap: wrap; gap: var(--space-4); }
.playlist-links .icon { width: var(--space-4); height: var(--space-4); }
/* About */
.about-intro { padding: 40px 0; background: var(--accent); border-bottom: 1px solid var(--border); }
.about-grid { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(235px, .8fr); gap: 70px; align-items: center; }
.about-intro h1 { margin: var(--space-4) 0 18px; font-size: clamp(2.1rem, 4vw, 3rem); line-height: 1.2; color: var(--primary); }
.about-lead { max-width: 570px; color: var(--muted); font-size: 1.04rem; line-height: 1.8; margin-bottom: 29px; }
.about-side { border-left: 3px solid var(--amber); background: var(--primary); min-height: 245px; padding: 28px; display: flex; flex-direction: column; justify-content: end; }
.about-side-icon { color: var(--amber); margin-bottom: auto; }
.about-side-icon .icon { width: 44px; height: 44px; }
.about-side .mini-label { color: #D8E6F1; }
.about-side p { color: white; font-size: 1.45rem; letter-spacing: -.03em; font-weight: 680; line-height: 1.45; margin: 13px 0 0; }
.narrow-content { max-width: 840px; }
.about-content h2 { color: var(--primary); margin: 10px 0 18px; }
.about-content p { color: var(--muted); line-height: 1.85; font-size: .96rem; }
.about-content strong { color: var(--primary); }
.placeholder-note { display: flex; align-items: center; gap: var(--space-2); background: #FFF4E7; border: 1px solid var(--amber); color: var(--text); border-radius: var(--radius-sm); padding: 11px 13px; font-size: .83rem; margin-bottom: 20px; }
.placeholder-note .icon { width: 17px; height: 17px; }
.about-rule { border-top: 1px solid var(--border); margin: 43px 0 var(--space-8); }
.about-feature-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: var(--space-4); margin-top: 25px; }
.about-feature-grid > div { border-top: 2px solid var(--amber); padding: 20px 0 0; }
.about-feature-grid .icon { color: var(--primary); width: 27px; height: 27px; }
.about-feature-grid h3 { color: var(--primary); font-size: .99rem; margin: var(--space-3) 0 var(--space-2); }
.about-feature-grid p { font-size: .8rem; line-height: 1.7; margin: 0; }
.youtube-cta { display: flex; align-items: center; justify-content: space-between; gap: 20px; background: transparent; border-top: 1px solid var(--border); padding: 24px 0 0; margin-top: 35px; }
.youtube-cta > div { display: flex; gap: 13px; align-items: start; }
.youtube-cta > div > .icon { width: 28px; height: 28px; color: var(--primary); }
.youtube-cta h3 { color: var(--primary); font-size: 1.06rem; margin: 1px 0 5px; }
.youtube-cta p { font-size: .8rem; margin: 0; }
/* 404 */
.not-found-section { min-height: 63vh; padding: 96px 0 116px; display: flex; align-items: center; }
.not-found-inner { max-width: 820px; }
.not-found-section h1 { font-size: clamp(2.8rem, 6vw, 5rem); letter-spacing: -.06em; color: var(--primary); margin: 20px 0; }
.not-found-section p { max-width: 500px; color: var(--muted); font-size: 1rem; margin-bottom: 30px; }
.not-found-actions { display: flex; gap: 10px; flex-wrap: wrap; }

/* Native collection choices and direct subject browsing. */
.search-collection { display: flex; gap: 0; width: fit-content; border: 1px solid var(--border); background: var(--surface); border-radius: var(--radius-sm); padding: 2px; margin: 0 0 var(--space-3); min-inline-size: 0; }
.search-collection label { position: relative; cursor: pointer; }
.search-collection input { position: absolute; width: 1px; height: 1px; opacity: 0; }
.search-collection span { display: inline-flex; align-items: center; justify-content: center; min-height: 44px; padding: 9px var(--space-4); font-size: .84rem; font-weight: 700; border-radius: var(--radius-sm); color: var(--muted); transition: color var(--interaction), background var(--interaction); }
.search-collection input:checked + span { background: var(--primary); color: white; }
.search-collection input:focus-visible + span { outline: 3px solid var(--focus); outline-offset: 2px; }
.search-collection label:hover input:not(:checked) + span { background: var(--accent); color: var(--primary); }
.subject-shortcuts { display: flex; flex-wrap: wrap; align-items: center; column-gap: 15px; margin-top: 14px; font-size: .78rem; }
.subject-shortcuts > span { color: var(--muted); }
.subject-shortcuts a { display: inline-flex; align-items: center; gap: 6px; min-height: 44px; font-weight: 700; color: var(--primary); }
.subject-shortcuts a:hover { text-decoration: underline; text-underline-offset: var(--space-1); }
.subject-shortcuts .icon { width: 14px; height: 14px; transition: transform var(--interaction); }
.subject-shortcuts a:hover .icon { transform: translateX(3px); }
.study-channel { display: inline-flex; align-items: center; gap: var(--space-2); margin-top: 8px; min-height: 44px; color: #D8E6F1; font-size: .82rem; font-weight: 650; }
.study-channel:hover { color: white; text-decoration: underline; text-underline-offset: var(--space-1); }
.study-channel:focus-visible { outline-color: var(--yellow); }
.study-channel .icon { width: var(--space-4); height: var(--space-4); }
.active-filters { display: flex; flex-wrap: wrap; gap: var(--space-2); margin-top: var(--space-4); }
.active-filters:empty { display: none; }
.filter-chip { display: inline-flex; align-items: center; gap: var(--space-2); max-width: 100%; min-height: 44px; padding: var(--space-2) var(--space-3); border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--accent); color: var(--primary); font-size: .8rem; overflow-wrap: anywhere; text-align: left; }
.filter-chip:hover { background: var(--border-light); }
.video-question { display: grid; gap: 2px; }
.video-direct-link { min-height: 44px; width: fit-content; padding: 5px 10px; font-size: .78rem; text-decoration: underline; text-underline-offset: 3px; }
.video-privacy-note { margin: var(--space-3) 0 0; padding: 10px var(--space-3); background: var(--accent); border-radius: var(--radius-sm); color: var(--muted); font-size: .8rem; }
.video-item-title { overflow-wrap: anywhere; }
.reset-button:disabled { color: var(--muted); cursor: default; opacity: .65; }
.reset-button:disabled:hover { background: transparent; }
.viewer-tab { scroll-margin-inline: var(--space-3); }
.viewer-tab:focus-visible { outline-offset: -4px; }

/* Small details shared across the library. */
.brand-name { display: grid; gap: 1px; line-height: 1.3; }
.brand-name small { color: var(--muted); font-size: .65rem; letter-spacing: .07em; font-weight: 550; }
.brand-mark svg { width: 100%; height: 100%; }
.math-figure { margin-bottom: 12px; border-bottom: 1px solid rgba(255,255,255,.2); padding-bottom: 10px; }
.math-figure svg { display: block; width: 100%; height: 72px; }
.math-figure text { font-family: var(--font-math); }
.math-caption { display: flex; justify-content: space-between; gap: var(--space-3); color: #D8E6F1; font-family: var(--font-mono); font-size: .68rem; letter-spacing: .02em; margin-top: 6px; }
.download-link { color: var(--text); background: #FFF4E7; }
.download-link:hover { color: var(--text); background: var(--amber); }
.paper-card .eyebrow { font-family: var(--font-mono); }
.video-item[aria-pressed="true"] { border-left: 3px solid var(--primary); }

/* Opt in before conditional animation styles are resolved on the next document. */
@view-transition { navigation: auto; }
@media (prefers-reduced-motion: reduce) {
  @view-transition { navigation: none; }
}

/* One motion language: a short paper turn, a gliding rule and responsive icons. */
.nav-indicator { position: absolute; left: 0; bottom: 0; height: 2px; background: var(--primary); pointer-events: none; opacity: 0; }
.has-indicator .nav-indicator { transition: transform 220ms cubic-bezier(.2,.7,.2,1), width 220ms cubic-bezier(.2,.7,.2,1), opacity 160ms ease; }
.has-indicator a[aria-current="page"] { border-bottom-color: transparent; }
.site-header { view-transition-name: masthead; }
.study-strip { color: var(--muted); background: var(--accent); border-bottom: 1px solid var(--border-light); }
.study-strip-inner { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 310px); align-items: center; gap: 8px 24px; padding-block: 9px; min-height: 48px; font-size: .75rem; line-height: 1.5; }
.exam-countdown { display: grid; grid-template-columns: max-content minmax(0, 1fr) max-content; align-items: center; gap: 3px 12px; min-width: 0; }
.strip-label { color: var(--primary); font-weight: 750; }
[data-exam-countdown] { font-variant-numeric: tabular-nums; min-width: 0; white-space: nowrap; }
.exam-source { color: var(--primary); text-decoration: underline; text-underline-offset: 3px; display: inline-flex; align-items: center; min-height: 28px; gap: 5px; }
.library-update { display: flex; align-items: center; gap: 7px; min-width: 0; max-width: 310px; }
[data-library-update] { min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.library-update-link { display: block; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.strip-dot { width: 5px; height: 5px; border-radius: 50%; background: var(--primary); flex: 0 0 auto; }
.year-chip, .card-arrow, .viewer-tab, .video-item { transition: background var(--interaction), color var(--interaction), border-color var(--interaction); }
.text-link .icon, .btn .icon, .card-arrow .icon, .action-link .icon, .study-channel .icon, .about-side-icon .icon { transition: transform 180ms ease; }
.math-point { transform-box: fill-box; transform-origin: center; transition: transform 220ms ease; }
.archive-intro { view-transition-name: collection-heading; }
.filters-card { view-transition-name: collection-filters; }
@media (hover: hover) and (prefers-reduced-motion: no-preference) {
  .text-link:hover .icon, .btn:hover .icon, .card-arrow:hover .icon, .study-channel:hover .icon { transform: translateX(3px); }
  .download-link:hover .icon { transform: translateY(2px); }
  .about-side:hover .about-side-icon .icon { transform: rotate(-4deg); }
  .hero-aside:hover .math-point { transform: scale(1.5); }
}
@media (prefers-reduced-motion: no-preference) {
  .nav-indicator { view-transition-name: collection-indicator; }
  :root { --page-shift: 22px; --page-turn: .5deg; }
  :root[data-page-direction="back"] { --page-shift: -22px; --page-turn: -.5deg; }
  ::view-transition-old(root) { animation: page-out 180ms ease-in both; }
  ::view-transition-new(root) { animation: page-in 240ms cubic-bezier(.2,.7,.2,1) both; }
  ::view-transition-old(masthead), ::view-transition-new(masthead) { animation: none; mix-blend-mode: normal; }
  ::view-transition-old(collection-indicator), ::view-transition-new(collection-indicator) { animation: none; mix-blend-mode: normal; }
  ::view-transition-old(collection-heading), ::view-transition-old(collection-filters) { animation: page-out 180ms ease-in both; }
  ::view-transition-new(collection-heading), ::view-transition-new(collection-filters) { animation: page-in 240ms cubic-bezier(.2,.7,.2,1) both; }
  ::view-transition-group(*) { animation-duration: 240ms; }
  .math-curve { stroke-dasharray: 1; animation: trace-curve 700ms 100ms ease-out both; }
  @keyframes trace-curve { from { stroke-dashoffset: 1; } to { stroke-dashoffset: 0; } }
  @keyframes page-in { from { opacity: 0; transform: translateX(var(--page-shift)) rotateY(var(--page-turn)); } to { opacity: 1; transform: none; } }
  @keyframes page-out { from { opacity: 1; transform: none; } to { opacity: 0; transform: translateX(calc(-1 * var(--page-shift))); } }
}