:root {
  --ink: #1a1a1a; --muted: #666; --faint: #999; --rule: #e4e4e4; --rule-strong: #d3d3d0;
  --link: #1a5fb4; --bg: #ffffff; --panel: #fbfbf9; --panel-2: #f6f6f3;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { font-family: -apple-system, "Helvetica Neue", Helvetica, Arial, sans-serif; color: var(--ink); background: var(--bg); line-height: 1.62; font-size: 18px; margin: 0; }
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }
a:focus-visible { outline: 2px solid var(--link); outline-offset: 2px; border-radius: 2px; }
.topbar { max-width: 54rem; margin: 0 auto; padding: 1.5rem 1.5rem 1.1rem; display: flex; justify-content: space-between; align-items: baseline; gap: 0.7rem 1.4rem; flex-wrap: wrap; border-bottom: 1px solid var(--rule); }
.brand { font-size: 1.4rem; font-weight: 800; letter-spacing: -0.01em; color: var(--ink); }
.brand:hover { text-decoration: none; }
.topnav { display: flex; flex-wrap: wrap; gap: 0.4rem 1.15rem; font-size: 0.92rem; align-items: baseline; }
.topnav a { color: var(--muted); }
.topnav a:hover { color: var(--link); }
.topnav a[aria-current="page"] { color: var(--link); font-weight: 600; }
main { max-width: 54rem; margin: 0 auto; padding: 1.3rem 1.5rem 0; }
.home-intro { max-width: 42rem; margin: 0 0 1.3rem; }
.home-intro p { font-size: 0.95rem; color: var(--muted); line-height: 1.55; margin: 0 0 0.7rem; }
.band-head { font-size: 0.68rem; letter-spacing: 0.11em; text-transform: uppercase; color: var(--link); font-weight: 700; margin: 1.7rem 0 0.4rem; }
.kicker { font-size: 0.68rem; letter-spacing: 0.11em; text-transform: uppercase; color: var(--link); font-weight: 700; margin: 0 0 0.2rem; }
.crumb { font-size: 0.82rem; color: var(--muted); margin: 0 0 0.4rem; }
.course-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr)); gap: 1rem; margin: 0.6rem 0 1.2rem; max-width: 44rem; }
.course-card { display: flex; flex-direction: column; gap: 0.25rem; padding: 1rem 1.1rem; border: 1px solid var(--rule-strong); border-radius: 6px; background: var(--panel); color: var(--ink); }
.course-card:hover { text-decoration: none; border-color: var(--link); }
.course-kicker { font-size: 0.66rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--link); font-weight: 700; }
.course-title { font-size: 1.15rem; font-weight: 700; }
.course-summary { font-size: 0.9rem; color: var(--muted); line-height: 1.5; }
.course-meta { font-size: 0.78rem; color: var(--faint); margin-top: 0.3rem; }
.lesson-list { list-style: none; padding: 0; margin: 0.8rem 0 2rem; max-width: 44rem; }
.lesson-row { padding: 0.65rem 0; border-top: 1px solid var(--rule); display: grid; grid-template-columns: 1fr; gap: 0.15rem; }
.lesson-list .lesson-row:last-of-type { border-bottom: 1px solid var(--rule); }
.lesson-row > a { color: var(--ink); }
.lesson-row > a:hover { text-decoration: none; color: var(--link); }
.lesson-num { color: var(--link); font-weight: 700; font-variant-numeric: tabular-nums; margin-right: 0.5rem; }
.lesson-title { font-weight: 700; }
.lesson-theme { color: var(--muted); font-size: 0.9rem; line-height: 1.5; }
.tags { display: inline-flex; flex-wrap: wrap; gap: 0.35rem; margin-top: 0.25rem; }
.tag { display: inline-block; font-size: 0.64rem; letter-spacing: 0.05em; text-transform: uppercase; border: 1px solid var(--rule-strong); border-radius: 999px; padding: 0.08rem 0.55rem; line-height: 1.5; background: var(--panel-2); color: var(--muted); }
.tag-prop { color: var(--link); }
.tag-closes { color: #2e7d4f; }
.tag-builds { color: var(--faint); }
.intro, .page, .lesson { max-width: 42rem; }
.intro h1, .page h1, .lesson h1 { font-size: 1.9rem; line-height: 1.16; margin: 0 0 1rem; letter-spacing: -0.02em; }
.intro p, .page p, .lesson p { margin: 0.85rem 0; }
.lesson { padding-top: 0.4rem; }
.factor-num { font-size: 2.6rem; font-weight: 800; color: var(--faint); line-height: 1; margin: 0 0 0.2rem; }
.factor-lead { font-size: 1.15rem; line-height: 1.45; font-weight: 500; color: var(--ink); margin: 0 0 1rem; }
p.tags { margin: 0 0 1.4rem; padding-bottom: 1.3rem; border-bottom: 1px solid var(--rule); }
.lesson h2, .page h2, .intro h2 { font-size: 1.05rem; margin: 1.6rem 0 0.4rem; letter-spacing: 0.01em; }
.lesson h2 { font-size: 0.78rem; letter-spacing: 0.09em; text-transform: uppercase; color: var(--link); }
.lesson ol, .page ol, .intro ol, .lesson ul, .page ul, .intro ul { padding-left: 1.3rem; }
.lesson li, .page li, .intro li { margin: 0.3rem 0; }
code { background: #f4f4f4; padding: 0.05em 0.35em; border-radius: 3px; font-size: 0.9em; }
pre { background: #f4f4f4; padding: 0.8rem 1rem; border-radius: 4px; overflow-x: auto; font-size: 0.85rem; }
pre code { background: none; padding: 0; }
table { border-collapse: collapse; font-size: 0.88rem; margin: 1rem 0; display: block; overflow-x: auto; }
th, td { border-top: 1px solid var(--rule); padding: 0.45rem 0.7rem 0.45rem 0; vertical-align: top; text-align: left; }
th { font-size: 0.72rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); }
blockquote { margin: 1.1rem 0; padding: 0.2rem 0 0.2rem 1.1rem; border-left: 3px solid var(--rule-strong); color: var(--muted); }
.pager { display: flex; justify-content: space-between; gap: 1rem; margin: 2.2rem 0 1rem; padding-top: 1rem; border-top: 1px solid var(--rule); font-size: 0.9rem; flex-wrap: wrap; }
.pager-home { color: var(--muted); }
.props-more { margin: 1.2rem 0 0; font-size: 0.9rem; }
.props-more a { font-weight: 600; }
.site-footer { margin: 3rem 0 2rem; padding-top: 1rem; border-top: 1px solid var(--rule); color: var(--faint); font-size: 0.82rem; max-width: 42rem; }
/* shift card */
.memo p:first-child { font-size: 1.05rem; color: var(--ink); }
.muted { color: var(--faint); }
.card { background: var(--panel); border: 1px solid var(--rule-strong); border-radius: 6px; padding: 0.9rem 1.1rem 0.6rem; margin: 0.4rem 0 1.4rem; }
.card dl { margin: 0; display: grid; grid-template-columns: 9rem 1fr; column-gap: 1rem; row-gap: 0.45rem; font-size: 0.93rem; }
.card dt { font-size: 0.68rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--link); font-weight: 700; padding-top: 0.2rem; }
.card dd { margin: 0; line-height: 1.5; }
.card dd p { margin: 0; }
.card p.tags { margin: 0.7rem 0 0.2rem; padding: 0; border: 0; }
@media (max-width: 40rem) { .card dl { grid-template-columns: 1fr; row-gap: 0.2rem; } .card dt { margin-top: 0.4rem; } }
/* content blocks: video, activity, todo */
.block { margin: 1.2rem 0; }
.block-head { font-size: 0.78rem; letter-spacing: 0.09em; text-transform: uppercase; color: var(--link); margin: 0 0 0.5rem; }
.frame { position: relative; aspect-ratio: 16 / 9; background: #000; border-radius: 6px; overflow: hidden; }
.frame iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
video { width: 100%; border-radius: 6px; background: #000; }
.placeholder { min-height: 4.5rem; display: flex; align-items: center; justify-content: center; border: 1px dashed var(--rule-strong); border-radius: 6px; background: var(--panel-2); }
.caption { font-size: 0.85rem; color: var(--muted); margin: 0.4rem 0 0; }
.block-activity { border-left: 3px solid var(--link); padding: 0.2rem 0 0.2rem 1rem; }
.activity-meta { margin: 0 0 0.3rem; display: flex; gap: 0.35rem; flex-wrap: wrap; }
.needs { font-size: 0.9rem; color: var(--muted); margin: 0.2rem 0 0; }
.todo { display: inline-block; font-size: 0.72rem; letter-spacing: 0.06em; text-transform: uppercase; font-weight: 700; color: #ab741a; background: rgba(171,116,26,0.10); border: 1px solid rgba(171,116,26,0.35); border-radius: 4px; padding: 0.05rem 0.45rem; vertical-align: middle; }
.props-list .tags a.tag-prop { text-transform: none; letter-spacing: 0; font-size: 0.72rem; }

.start-cta { margin: 0.4rem 0 0.8rem; font-size: 1rem; } .start-cta a { font-weight: 700; }
.legend { font-size: 0.8rem; }
.course-total { font-size: 0.88rem; margin: 0.2rem 0 0; }

.block-skill { border-left: 3px solid #2e7d4f; padding: 0.2rem 0 0.2rem 1rem; }
.block-skill p { margin: 0 0 0.4rem; }
.block-skill pre { margin: 0; font-size: 0.8rem; }
.prompt { display: flex; gap: 0.6rem; align-items: flex-start; background: #f4f4f4; border-radius: 4px; padding: 0.6rem 0.8rem; margin: 0 0 0.5rem; }
.prompt code { background: none; padding: 0; font-size: 0.86rem; line-height: 1.5; flex: 1; word-break: break-word; }
button.copy { font: inherit; font-size: 0.78rem; font-weight: 600; color: var(--link); background: var(--bg); border: 1px solid var(--rule-strong); border-radius: 4px; padding: 0.15rem 0.6rem; cursor: pointer; white-space: nowrap; }
button.copy:hover { border-color: var(--link); }
.small { font-size: 0.85rem; }