/* Open Semester: materials home. "Midnight Lecture" palette (style/house-style.md). No JavaScript. */

@font-face { font-family: "Inter"; font-weight: 400; font-style: normal; font-display: swap; src: url("/fonts/inter-regular.woff2") format("woff2"); }
@font-face { font-family: "Inter"; font-weight: 500; font-style: normal; font-display: swap; src: url("/fonts/inter-medium.woff2") format("woff2"); }
@font-face { font-family: "Inter"; font-weight: 600; font-style: normal; font-display: swap; src: url("/fonts/inter-semibold.woff2") format("woff2"); }
@font-face { font-family: "EB Garamond"; font-weight: 400 800; font-style: normal; font-display: swap; src: url("/fonts/eb-garamond.woff2") format("woff2"); }
@font-face { font-family: "EB Garamond"; font-weight: 400 800; font-style: italic; font-display: swap; src: url("/fonts/eb-garamond-italic.woff2") format("woff2"); }

:root {
  --bg: #14171F;
  --bg-deep: #10131A;
  --card: #1D222D;
  --card-hi: #222835;
  --border: #2C3442;
  --hair: #232937;
  --text: #ECEFF4;
  --muted: #9AA3B2;
  --faint: #838C9C;           /* 5.2:1 on --bg */
  --accent: #F2B84B;
  --coral: #FF7A6B;
  --blue: #5CC8FF;
  --green: #7BE0A3;
  --sans: "Inter", ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --serif: "EB Garamond", "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --wrap: 1120px;
  --gutter: clamp(20px, 5vw, 48px);
  --radius: 14px;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.6;
  font-feature-settings: "cv11", "ss01";
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
main { flex: 1 0 auto; }
img, svg { display: block; }
sup, sub { font-size: 0.68em; line-height: 0; }

a { color: var(--text); text-decoration: underline; text-decoration-color: rgba(242, 184, 75, 0.55);
    text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--accent); text-decoration-color: var(--accent); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 6px; }

.wrap { max-width: var(--wrap); margin: 0 auto; padding: 0 var(--gutter); }

.skip { position: absolute; left: 12px; top: -60px; z-index: 10; background: var(--accent); color: var(--bg);
        padding: 10px 16px; border-radius: 8px; font-weight: 600; text-decoration: none; }
.skip:focus { top: 12px; color: var(--bg); }

/* ---------- header / footer */
.site-header { border-bottom: 1px solid var(--hair); }
.header-inner { display: flex; align-items: center; justify-content: space-between; min-height: 72px; gap: 16px; }
.brand { display: inline-flex; align-items: center; gap: 12px; min-height: 44px; text-decoration: none;
         font-weight: 600; font-size: 16px; letter-spacing: -0.005em; color: var(--text); }
.brand .mark { color: var(--accent); }
.brand:hover { color: var(--text); }
.site-nav { display: flex; gap: 4px; }
.site-nav a { display: inline-flex; align-items: center; min-height: 44px; padding: 0 14px; border-radius: 10px;
              text-decoration: none; color: var(--muted); font-size: 15px; font-weight: 500; }
.site-nav a:hover { color: var(--text); background: var(--card); }
.site-nav a[aria-current="page"] { color: var(--text); }
.site-nav a[aria-current="page"]::after { content: ""; display: block; width: 4px; height: 4px; border-radius: 2px;
              background: var(--accent); margin-left: 8px; }

.site-footer { margin-top: 120px; border-top: 1px solid var(--hair); background: var(--bg-deep); }
.footer-inner { display: grid; grid-template-columns: auto 1fr auto; gap: 24px 40px; align-items: center;
                padding-top: 36px; padding-bottom: 40px; }
.footer-brand { display: inline-flex; align-items: center; gap: 10px; font-weight: 600; font-size: 15px; }
.footer-brand .mark { color: var(--accent); }
.footer-note { margin: 0; color: var(--muted); font-size: 14px; }
.footer-note a { color: var(--muted); }
.footer-nav { display: flex; flex-wrap: wrap; gap: 0 4px; }
.footer-nav a { display: inline-flex; align-items: center; min-height: 44px; padding: 0 10px; color: var(--muted);
                font-size: 14px; text-decoration: none; }
.footer-nav a:hover { color: var(--text); }

/* ---------- type */
.eyebrow { margin: 0 0 18px; color: var(--muted); font-size: 13px; font-weight: 600; letter-spacing: 0.12em;
           text-transform: uppercase; display: flex; align-items: center; gap: 12px; }
.eyebrow::before { content: ""; width: 22px; height: 2px; border-radius: 1px; background: var(--accent); flex: none; }
.eyebrow .sep { color: var(--faint); }
.title { font-family: var(--serif); font-weight: 500; font-size: clamp(2.35rem, 5.2vw, 3.6rem); line-height: 1.06;
         letter-spacing: -0.012em; margin: 0 0 24px; max-width: 18em; text-wrap: balance; }
.title-xl { font-size: clamp(2.8rem, 7vw, 5rem); }
.title-hero { font-size: clamp(2.7rem, 7.4vw, 5.6rem); line-height: 1.0; letter-spacing: -0.018em; max-width: 11em; }
.lead { margin: 0; color: var(--muted); font-size: clamp(1.05rem, 1.6vw, 1.2rem); line-height: 1.6; max-width: 40em; }
.h2 { font-family: var(--serif); font-weight: 500; font-size: 1.75rem; line-height: 1.2; margin: 0 0 16px; letter-spacing: -0.005em; }
.h2-big { font-size: clamp(1.9rem, 3.4vw, 2.5rem); margin: 0; }
.h2-small { font-family: var(--sans); font-size: 13px; font-weight: 600; letter-spacing: 0.12em; text-transform: uppercase;
            color: var(--muted); margin-bottom: 12px; }
.h3 { font-family: var(--serif); font-weight: 500; font-size: 1.4rem; line-height: 1.25; margin: 0 0 10px; }

/* ---------- breadcrumbs */
.crumbs ol { list-style: none; display: flex; flex-wrap: wrap; align-items: center; margin: 0 0 28px; padding: 0;
             font-size: 14px; color: var(--muted); }
.crumbs li { display: flex; align-items: center; }
.crumbs li + li::before { content: "/"; color: var(--border); margin: 0 6px; }
.crumbs a { display: inline-flex; align-items: center; min-height: 44px; color: var(--muted); text-decoration: none; }
.crumbs a:hover { color: var(--text); text-decoration: underline; text-decoration-color: var(--accent); }
.crumbs [aria-current] { color: var(--text); }

/* ---------- page head */
.page-head { padding-top: 40px; padding-bottom: 48px; }
.facts { display: flex; flex-wrap: wrap; gap: 12px 40px; margin: 32px 0 0; }
.facts div { border-left: 1px solid var(--border); padding-left: 14px; }
.facts dt { font-size: 12px; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; color: var(--faint); }
.facts dd { margin: 2px 0 0; font-size: 17px; font-variant-numeric: tabular-nums; }

/* ---------- buttons */
.btn { display: inline-flex; align-items: center; gap: 10px; min-height: 48px; padding: 0 22px; border-radius: 12px;
       border: 1px solid var(--border); background: var(--card); color: var(--text); text-decoration: none;
       font-weight: 500; font-size: 15px; }
.btn:hover { border-color: #3A4456; background: var(--card-hi); color: var(--text); }
.btn-primary { background: var(--accent); border-color: var(--accent); color: #17130A; font-weight: 600; }
.btn-primary:hover { background: #F6C566; border-color: #F6C566; color: #17130A; }
.btn .ico { width: 14px; height: 14px; }
.arrow { transition: transform .15s ease; }
a:hover .arrow { transform: translateX(3px); }
.actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 32px; }

/* ---------- home hero */
.hero { position: relative; overflow: hidden; border-bottom: 1px solid var(--hair);
        background: radial-gradient(1200px 520px at 85% 0%, rgba(92, 200, 255, 0.045), transparent 60%), var(--bg); }
.hero-inner { position: relative; padding-top: clamp(64px, 11vw, 132px); padding-bottom: clamp(64px, 10vw, 120px); }
.hero .title, .hero .lead, .hero .eyebrow, .hero .btn { position: relative; z-index: 1; }
.lead-hero { margin-bottom: 40px; max-width: 34em; }
.sky { position: absolute; right: calc(var(--gutter) - 40px); top: 24px; width: 470px; height: auto; z-index: 0; }
.sky-grid path { stroke: #9AA3B2; stroke-opacity: 0.09; stroke-width: 1; stroke-dasharray: 2 6; }
.sky-lines line { stroke: #9AA3B2; stroke-opacity: 0.26; stroke-width: 1; }
.star { fill: #DCE2EC; fill-opacity: 0.8; }
.star-warm { fill: var(--coral); fill-opacity: 0.9; }
.star-cool { fill: var(--blue); fill-opacity: 0.9; }
.halo { fill-opacity: 0.1; }
.sky-label { font: 500 11px var(--sans); letter-spacing: 0.06em; fill: #9AA3B2; fill-opacity: 0.5; }

/* ---------- sections */
.section { padding-top: 88px; }
.section-head { display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: 8px 32px;
                margin-bottom: 28px; padding-bottom: 18px; border-bottom: 1px solid var(--border); }
.section-note { margin: 0; color: var(--muted); font-size: 15px; max-width: 34em; }

/* ---------- course card (home) */
.course { display: grid; gap: 14px; padding: clamp(28px, 4vw, 44px); border-radius: var(--radius); text-decoration: none;
          background: linear-gradient(180deg, var(--card), #1A1F29); border: 1px solid var(--border); color: var(--text);
          position: relative; }
.course:hover { border-color: #3A4456; color: var(--text); }
.course-kicker { color: var(--muted); font-size: 13px; font-weight: 600; letter-spacing: 0.12em; text-transform: uppercase; }
.course-title { font-family: var(--serif); font-size: clamp(2.2rem, 4.6vw, 3.2rem); line-height: 1.05; font-weight: 500; letter-spacing: -0.01em; }
.course-text { color: var(--muted); font-size: 17px; max-width: 36em; }
.course-stats { color: var(--text); font-size: 15px; }
.course-stats span { white-space: nowrap; }
.course-foot { display: flex; flex-wrap: wrap; align-items: center; gap: 12px 20px; margin-top: 14px; padding-top: 22px;
               border-top: 1px solid var(--border); }
.course-status { color: var(--muted); font-size: 15px; font-variant-numeric: tabular-nums; }
.course-go { margin-left: auto; display: inline-flex; gap: 8px; align-items: center; font-weight: 600; color: var(--accent); }
.course:hover .arrow { transform: translateX(3px); }

.segs { display: grid; grid-template-columns: repeat(13, 1fr); gap: 4px; width: 100%; max-width: 420px; }
.seg { height: 6px; border-radius: 3px; background: var(--border); }
.seg.on { background: var(--accent); }
.segs-small { width: 170px; gap: 3px; }
.segs-small .seg { height: 4px; }

.more { margin-top: 20px; padding: 26px 28px; border-radius: var(--radius); border: 1px dashed var(--border); color: var(--muted); }
.more p { margin: 0; }
.more-title { color: var(--text); font-family: var(--serif); font-size: 1.3rem; margin-bottom: 4px !important; }

.principles { display: grid; grid-template-columns: repeat(3, 1fr); gap: 40px; border-top: 1px solid var(--border); padding-top: 36px; }
.principles p { margin: 0; color: var(--muted); }

/* ---------- course page */
.progress { margin-top: 36px; display: grid; gap: 12px; }
.progress-label { margin: 0; color: var(--muted); font-size: 15px; }
.progress-label strong { color: var(--text); font-weight: 600; }
.course-head .btn { margin-top: 28px; }
.about-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; margin: 0; padding: 28px 0;
              border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.about-grid dt { font-size: 12px; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; color: var(--faint); margin-bottom: 6px; }
.about-grid dd { margin: 0; color: var(--muted); font-size: 15px; }

.start { margin-top: 48px; display: grid; grid-template-columns: 1fr auto; gap: 6px 32px; align-items: end;
         padding: 28px 32px; border-radius: var(--radius); background: var(--card); border: 1px solid var(--border);
         border-left: 3px solid var(--accent); text-decoration: none; color: var(--text); }
.start:hover { background: var(--card-hi); color: var(--text); }
.start-kicker { grid-column: 1; font-size: 13px; font-weight: 600; letter-spacing: 0.12em; text-transform: uppercase; color: var(--accent); }
.start-title { grid-column: 1; font-family: var(--serif); font-size: 1.7rem; line-height: 1.2; }
.start-text { grid-column: 1; color: var(--muted); font-size: 15px; }
.start-go { grid-column: 2; grid-row: 1 / span 3; align-self: center; display: inline-flex; gap: 8px; font-weight: 600; white-space: nowrap; }
.start:hover .arrow { transform: translateX(3px); }

.week { display: grid; grid-template-columns: 200px 1fr; gap: 0 32px; padding: 26px 0; border-bottom: 1px solid var(--hair); }
.week-head { display: flex; flex-direction: column; gap: 14px; }
.week-title { font-family: var(--serif); font-weight: 500; font-size: 1.6rem; line-height: 1.2; margin: 6px 0 0; }
.week-title a { text-decoration: none; display: inline-flex; min-height: 44px; align-items: center; margin-top: -8px; }
.week-title a:hover { color: var(--accent); }
.week.is-soon .week-title { color: var(--faint); }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip { display: inline-flex; align-items: center; gap: 7px; min-height: 44px; padding: 0 14px; border-radius: 10px;
        background: var(--card); border: 1px solid var(--border); text-decoration: none; font-size: 14px; font-weight: 500; }
.chip:hover { border-color: #3A4456; color: var(--text); background: var(--card-hi); }
.chip .ico { width: 14px; height: 14px; color: var(--accent); }
.chip-meta { color: var(--faint); font-size: 12px; font-weight: 500; }

.exam { display: grid; grid-template-columns: 200px 1fr auto; gap: 8px 32px; align-items: center; padding: 22px 0;
        border-bottom: 1px solid var(--hair); }
.exam-label { font-family: var(--serif); font-size: 1.3rem; color: var(--faint); }
.exam-note { color: var(--faint); font-size: 15px; }

/* ---------- rows (lectures, chapters) */
.rows { list-style: none; margin: 0; padding: 0; }
.rows li + li .row { border-top: 1px solid var(--hair); }
.row { display: grid; grid-template-columns: 52px 1fr auto; align-items: center; gap: 16px; min-height: 52px; padding: 10px 12px;
       margin: 0 -12px; border-radius: 10px; text-decoration: none; color: var(--text); }
a.row:hover { background: var(--card); color: var(--text); }
a.row:hover + * { border-color: transparent; }
.row-num { font-size: 13px; font-weight: 600; color: var(--muted); font-variant-numeric: tabular-nums; letter-spacing: 0.02em; }
.row-title { font-size: 16px; line-height: 1.4; display: flex; flex-direction: column; gap: 2px; }
.row-sub { font-size: 14px; color: var(--muted); }
.row-meta { font-size: 14px; color: var(--muted); font-variant-numeric: tabular-nums; display: inline-flex; align-items: center; gap: 8px; white-space: nowrap; }
.row-meta .ico { width: 14px; height: 14px; color: var(--accent); }
.row.is-soon { color: var(--faint); min-height: 40px; padding-top: 7px; padding-bottom: 7px; }
.row.is-soon .row-num, .row.is-soon .row-sub { color: var(--faint); }
.tag { display: inline-block; font-size: 12px; font-weight: 500; color: var(--faint); border: 1px solid var(--border);
       border-radius: 999px; padding: 2px 10px; white-space: nowrap; letter-spacing: 0.01em; }
.rows-book .row-num { font-family: var(--serif); font-size: 1.25rem; font-weight: 500; color: var(--muted); }

/* ---------- item pages */
.split { display: grid; grid-template-columns: minmax(0, 1fr) 340px; gap: 0 56px; align-items: start; }
.split-main { display: contents; }
.split-main > * { grid-column: 1; }
.split-side { grid-column: 2; grid-row: 1 / span 8; position: sticky; top: 24px; }
.block { margin-top: 48px; }

.video { aspect-ratio: 16 / 9; border-radius: var(--radius); border: 1px solid var(--border); position: relative; overflow: hidden;
         background:
           linear-gradient(rgba(44, 52, 66, 0.45) 1px, transparent 1px) 0 0 / 40px 40px,
           linear-gradient(90deg, rgba(44, 52, 66, 0.45) 1px, transparent 1px) 0 0 / 40px 40px,
           var(--bg-deep);
         display: grid; place-items: center; text-align: center; }
.video::after { content: ""; position: absolute; left: 0; right: 0; bottom: 0; height: 3px; background: var(--border); }
.video-inner { padding: 24px; max-width: 30em; }
.video-mark { color: var(--border); margin: 0 auto 18px; }
.video-title { font-family: var(--serif); font-size: clamp(1.4rem, 2.6vw, 1.9rem); margin: 0 0 8px; }
.video-note { margin: 0; color: var(--muted); font-size: 15px; }
.video.is-live { aspect-ratio: auto; display: flex; flex-wrap: wrap; align-items: center; gap: 12px 20px; padding: 24px;
                 text-align: left; justify-content: flex-start; }
.video.is-live::after { display: none; }

.parts { margin: 0; padding: 0; list-style: none; counter-reset: part; }
.parts li { counter-increment: part; display: grid; grid-template-columns: 40px 1fr; padding: 12px 0; border-top: 1px solid var(--hair); }
.parts li:last-child { border-bottom: 1px solid var(--hair); }
.parts li::before { content: counter(part, decimal-leading-zero); color: var(--faint); font-size: 13px; font-weight: 600;
                    font-variant-numeric: tabular-nums; padding-top: 3px; }

.callout { margin-top: 24px; padding: 18px 22px; border-radius: 12px; background: var(--card); border: 1px solid var(--border); }
.callout p { margin: 0; color: var(--muted); }
.callout .callout-title { color: var(--text); font-weight: 600; margin-bottom: 4px; }

.files { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.file { display: grid; grid-template-columns: 18px 1fr; gap: 2px 12px; padding: 14px 16px; min-height: 44px; border-radius: 12px;
        background: var(--card); border: 1px solid var(--border); text-decoration: none; color: var(--text); }
a.file:hover { border-color: #3A4456; background: var(--card-hi); color: var(--text); }
.file .ico { width: 16px; height: 16px; color: var(--accent); margin-top: 3px; grid-row: 1 / span 2; }
.file-label { font-weight: 500; font-size: 15px; }
.file-meta { grid-column: 2; color: var(--muted); font-size: 13px; }
.file.is-soon { grid-template-columns: 1fr auto; align-items: center; background: transparent; border-style: dashed; color: var(--faint); }
.file.is-soon .file-label { font-weight: 400; }
.side-note { color: var(--muted); font-size: 15px; margin: 20px 0 0; }

.topics { margin: 0; }
.topics div { display: grid; grid-template-columns: 120px 1fr; gap: 16px; padding: 12px 0; border-top: 1px solid var(--hair); }
.topics dt { color: var(--muted); font-size: 14px; padding-top: 1px; }
.topics dd { margin: 0; }

.prevnext { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 72px; padding-top: 28px; border-top: 1px solid var(--border); }
.pn { display: flex; flex-direction: column; gap: 4px; padding: 16px 20px; min-height: 44px; border-radius: 12px; text-decoration: none; color: var(--text); }
a.pn { border: 1px solid var(--border); }
a.pn:hover { background: var(--card); color: var(--text); }
.pn-next { text-align: right; }
.pn-label { font-size: 12px; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; color: var(--muted); }
.pn-title { font-family: var(--serif); font-size: 1.2rem; line-height: 1.3; }
.pn.is-soon { border: 1px dashed var(--border); color: var(--faint); }
.pn.is-soon .pn-label { color: var(--faint); }

/* ---------- about */
.prose-wrap { display: grid; grid-template-columns: minmax(0, 46rem); }
.prose { font-size: 17px; }
.prose p { margin: 0 0 18px; color: #D5DAE3; }
.prose .h2 { margin-top: 56px; padding-top: 28px; border-top: 1px solid var(--border); }
.table-wrap { overflow-x: auto; margin-top: 8px; }
table { width: 100%; border-collapse: collapse; font-size: 15px; }
th { text-align: left; font-size: 12px; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; color: var(--faint);
     padding: 10px 16px 10px 0; border-bottom: 1px solid var(--border); }
td { padding: 12px 16px 12px 0; border-bottom: 1px solid var(--hair); vertical-align: top; color: #D5DAE3; }
td:first-child { color: var(--text); font-weight: 500; }

.notfound { padding-top: 96px; min-height: 50vh; }

/* ---------- responsive */
@media (max-width: 960px) {
  .split { grid-template-columns: minmax(0, 1fr); }
  .split-main > * { order: 3; }
  .split-main > :first-child { order: 1; }
  .split-side { grid-column: 1; grid-row: auto; order: 2; position: static; margin-top: 32px; }
  .sky { width: 380px; right: -60px; opacity: 0.75; }
}
@media (max-width: 760px) {
  .principles, .about-grid { grid-template-columns: 1fr; gap: 24px; }
  .week, .exam { grid-template-columns: 1fr; }
  .week-head { flex-direction: row; flex-wrap: wrap; align-items: center; justify-content: space-between; margin-bottom: 10px; }
  .footer-inner { grid-template-columns: 1fr; gap: 8px; }
  .footer-nav { margin-left: -10px; }
  .start { grid-template-columns: 1fr; padding: 24px; }
  .start-go { grid-column: 1; grid-row: auto; margin-top: 10px; }
  .section { padding-top: 64px; }
  .site-footer { margin-top: 88px; }
}
@media (max-width: 520px) {
  body { font-size: 16px; }
  .header-inner { min-height: 64px; }
  .site-nav a { padding: 0 10px; font-size: 14px; }
  .site-nav a[aria-current="page"]::after { display: none; }
  .brand span { font-size: 15px; }
  .sky { width: 250px; right: -96px; top: -34px; opacity: 0.4; }
  .title-hero br { display: none; }
  .row { grid-template-columns: 40px 1fr; gap: 4px 12px; }
  .row-meta { grid-column: 2; }
  .row.is-soon .row-meta { display: none; }
  .row.is-soon { grid-template-columns: 40px 1fr; }
  .prevnext { grid-template-columns: 1fr; }
  .pn-next { text-align: left; }
  .pn.is-empty { display: none; }
  .course-go { margin-left: 0; width: 100%; }
  .exam { gap: 4px; }
  .topics div { grid-template-columns: 1fr; gap: 2px; }
  .facts { gap: 12px 28px; }
  .video { aspect-ratio: auto; min-height: 220px; }
  .video-inner { padding: 32px 20px; }
}
@media (prefers-reduced-motion: reduce) { .arrow { transition: none; } }
@media print {
  .site-header, .site-footer, .prevnext, .sky { display: none; }
  body { background: #fff; color: #000; }
}