/* Tech With Kobina: members' lesson site */

/* ---------- tokens ---------- */
:root {
  --bg: #ffffff;
  --bg-subtle: #f7f7f8;
  --surface: #ffffff;
  --border: #e7e7ea;
  --border-strong: #d6d6db;
  --text: #121214;
  --text-2: #4c4c55;
  --text-3: #7a7a84;
  --accent: #0a6c61;
  --accent-soft: #edf6f5;
  --primary: #121214;
  --primary-text: #ffffff;
  --primary-hover: #2b2b30;
  --done: #15803d;
  --note-bg: #f5f8fb;
  --note-border: #2f6fb0;
  --warn-bg: #fdf8ef;
  --warn-border: #b7791f;
  --warn-text: #8a5a10;
  --danger: #c02626;
  --code-bg: #f4f4f5;
  --shadow-sm: 0 1px 2px rgba(18, 18, 20, .04);
  --shadow: 0 1px 2px rgba(18, 18, 20, .04), 0 2px 8px rgba(18, 18, 20, .04);
  --radius: 10px;
  --radius-sm: 7px;
  --font: 'Inter', ui-sans-serif, system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  --mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, monospace;
  --topbar: 60px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0d0d0f; --bg-subtle: #141417; --surface: #141417; --border: #25252a; --border-strong: #34343a;
    --text: #ececef; --text-2: #a9a9b2; --text-3: #7d7d87;
    --accent: #4fc1b2; --accent-soft: #11211f;
    --primary: #ececef; --primary-text: #111113; --primary-hover: #ffffff;
    --done: #4ade80; --note-bg: #111821; --note-border: #5b9bd8; --warn-bg: #1d1810; --warn-border: #d39b45; --warn-text: #e8b766;
    --danger: #f87171; --code-bg: #1c1c20;
    --shadow-sm: none; --shadow: none;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0d0d0f; --bg-subtle: #141417; --surface: #141417; --border: #25252a; --border-strong: #34343a;
  --text: #ececef; --text-2: #a9a9b2; --text-3: #7d7d87;
  --accent: #4fc1b2; --accent-soft: #11211f;
  --primary: #ececef; --primary-text: #111113; --primary-hover: #ffffff;
  --done: #4ade80; --note-bg: #111821; --note-border: #5b9bd8; --warn-bg: #1d1810; --warn-border: #d39b45; --warn-text: #e8b766;
  --danger: #f87171; --code-bg: #1c1c20;
  --shadow-sm: none; --shadow: none;
  color-scheme: dark;
}

/* ---------- base ---------- */
* { box-sizing: border-box; }
html { scroll-padding-top: calc(var(--topbar) + 20px); -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text); font: 15.5px/1.65 var(--font); -webkit-font-smoothing: antialiased; font-feature-settings: 'cv11', 'ss01'; }
/* Short pages: the footer sits at the bottom of the window, not halfway up. */
body { min-height: 100vh; display: flex; flex-direction: column; }
body > main { flex: 1 0 auto; }

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 3px; }
img { max-width: 100%; }
[hidden] { display: none !important; }
.icon { width: 16px; height: 16px; flex: none; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 4px; }
h1, h2, h3 { font-weight: 650; letter-spacing: -.02em; }
.link-quiet { color: var(--text-3); text-decoration: none; }
.link-quiet:hover { color: var(--text); }
.kicker { margin: 0 0 12px; font-size: 13.5px; font-weight: 500; color: var(--text-3); }

/* ---------- top bar ---------- */
.topbar { position: sticky; top: 0; z-index: 30; height: var(--topbar); background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px); border-bottom: 1px solid var(--border); }
.topbar-inner { max-width: 1400px; height: 100%; margin: 0 auto; padding: 0 24px; display: flex; align-items: center; justify-content: space-between; gap: 16px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--text); text-decoration: none; font-weight: 600; font-size: 15px; letter-spacing: -.01em; }
.brand-mark { width: 28px; height: 28px; border-radius: 7px; display: grid; place-items: center; background: var(--primary); color: var(--primary-text);
  font-size: 11.5px; font-weight: 700; letter-spacing: .02em; }
.topbar-right { display: flex; align-items: center; gap: 12px; }
.icon-btn { border: 1px solid transparent; background: transparent; color: var(--text-2); width: 34px; height: 34px; border-radius: var(--radius-sm);
  cursor: pointer; display: inline-grid; place-items: center; }
.icon-btn:hover { background: var(--bg-subtle); color: var(--text); }
.theme-toggle .i-moon { display: none; }
:root[data-theme="dark"] .theme-toggle .i-sun { display: none; }
:root[data-theme="dark"] .theme-toggle .i-moon { display: inline; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-toggle .i-sun { display: none; }
  :root:not([data-theme="light"]) .theme-toggle .i-moon { display: inline; }
}
.theme-toggle span { display: inline-grid; }
.member-chip { display: inline-flex; align-items: center; gap: 14px; font-size: 14px; color: var(--text-2); }
.member-name { font-weight: 500; color: var(--text); }

/* ---------- buttons ---------- */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; height: 38px; padding: 0 16px; border-radius: var(--radius-sm);
  font: 500 14.5px/1 var(--font); text-decoration: none; border: 1px solid transparent; cursor: pointer; white-space: nowrap; transition: background .15s, border-color .15s; }
.btn-primary { background: var(--primary); color: var(--primary-text); }
.btn-primary:hover { background: var(--primary-hover); }
.btn-secondary { background: var(--surface); color: var(--text); border-color: var(--border-strong); box-shadow: var(--shadow-sm); }
.btn-secondary:hover { background: var(--bg-subtle); }
.btn-lg { height: 44px; padding: 0 20px; font-size: 15px; }
.btn-small { height: 32px; padding: 0 12px; font-size: 13.5px; }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.badge { flex: none; white-space: nowrap; display: inline-flex; align-items: center; gap: 6px; height: 24px; padding: 0 9px; border-radius: 999px; font-size: 12.5px; font-weight: 500;
  border: 1px solid var(--border); color: var(--text-2); background: var(--bg-subtle); }
.badge .icon { width: 13px; height: 13px; }

/* ---------- landing ---------- */
.hero { max-width: 1120px; margin: 0 auto; padding: 96px 24px 56px; }
.hero h1 { font-size: clamp(34px, 5vw, 52px); line-height: 1.08; letter-spacing: -.035em; margin: 0 0 20px; max-width: 760px; }
.lead { font-size: 17.5px; line-height: 1.6; color: var(--text-2); max-width: 640px; margin: 0; }
.hero .lead { margin-bottom: 32px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 10px; }
.hero-facts { display: flex; flex-wrap: wrap; gap: 10px 28px; padding: 0; margin: 40px 0 0; list-style: none; color: var(--text-2); font-size: 14px; }
.hero-facts li { display: flex; align-items: center; gap: 8px; }
.hero-facts .icon { color: var(--text-3); }
.section { max-width: 1120px; margin: 0 auto; padding: 48px 24px; border-top: 1px solid var(--border); }
.section-tight { border-top: 0; padding-top: 8px; }
.section-head { display: flex; justify-content: space-between; align-items: baseline; gap: 16px; margin-bottom: 24px; flex-wrap: wrap; }
.section-head h2 { font-size: 22px; margin: 0; }
.section-head p { margin: 0; color: var(--text-3); font-size: 14px; }
.steps-row { list-style: none; padding: 0; margin: 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 260px), 1fr)); gap: 32px; }
.steps-row span { display: block; font: 500 13px var(--mono); color: var(--text-3); margin-bottom: 10px; }
.steps-row strong { display: block; font-size: 16px; font-weight: 600; margin-bottom: 6px; }
.steps-row p { margin: 0; color: var(--text-2); font-size: 14.5px; }
.page-head { max-width: 1120px; margin: 0 auto; padding: 56px 24px 24px; }
.page-head h1 { font-size: 34px; margin: 0 0 10px; letter-spacing: -.03em; }
.footer { border-top: 1px solid var(--border); margin-top: 32px; }
.footer-inner { max-width: 1120px; margin: 0 auto; padding: 16px 24px; display: flex; flex-wrap: wrap; align-items: center; gap: 4px 24px; justify-content: space-between; color: var(--text-3); font-size: 13.5px; }
.footer a { color: inherit; }
.footer-links { display: inline-flex; gap: 20px; }
.doc { max-width: 720px; margin: 0 auto; padding: 72px 24px 24px; }
.doc h1 { font-size: 36px; letter-spacing: -.03em; margin: 0 0 4px; }
.doc .prose > p:first-child { color: var(--text-3); font-size: 14px; margin-top: 0; }
.doc .prose h2 { font-size: 19px; margin-top: 40px; }
.message-foot { margin: 32px 0 0; font-size: 13px; }

/* ---------- project cards ---------- */
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 440px), 1fr)); gap: 20px; }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; display: flex; flex-direction: column; gap: 14px; box-shadow: var(--shadow); }
.card-head { display: flex; justify-content: space-between; align-items: flex-start; gap: 12px; min-height: 24px; }
.card-topics { margin: 0; font-size: 13px; line-height: 24px; color: var(--text-3); flex: 1; min-width: 0; }
.card h3 { margin: 0; font-size: 19px; line-height: 1.3; }
.card-blurb { margin: 0; color: var(--text-2); font-size: 15px; }
.card-meta { list-style: none; padding: 0; margin: 0; display: flex; flex-wrap: wrap; gap: 6px 20px; color: var(--text-2); font-size: 13.5px; }
.card-meta li { display: flex; align-items: center; gap: 7px; }
.card-meta .icon { color: var(--text-3); width: 15px; height: 15px; }
.card-lessons { border-top: 1px solid var(--border); padding-top: 12px; }
.card-lessons summary { cursor: pointer; color: var(--text-2); font-weight: 500; font-size: 14px; list-style: none; display: flex; align-items: center; gap: 6px; }
.card-lessons summary::-webkit-details-marker { display: none; }
.card-lessons summary::before { content: ''; width: 6px; height: 6px; border-right: 1.6px solid currentColor; border-bottom: 1.6px solid currentColor; transform: rotate(-45deg); transition: transform .15s; margin-right: 4px; }
.card-lessons[open] summary::before { transform: rotate(45deg); }
.card-lessons ol { list-style: none; padding: 0; margin: 12px 0 0; display: grid; gap: 8px; }
.card-lessons li { display: flex; align-items: center; gap: 10px; font-size: 14px; color: var(--text-2); }
.card-actions { margin-top: auto; padding-top: 4px; display: flex; gap: 10px; flex-wrap: wrap; }
.card-locked h3 { color: var(--text-2); }
.card-locked .card-blurb { color: var(--text-3); }
.badge-lock { color: var(--warn-text); background: var(--warn-bg); border-color: color-mix(in srgb, var(--warn-border) 35%, transparent); }
.access-note { margin: 16px 0 0; padding: 12px 14px; border-radius: var(--radius-sm); background: var(--warn-bg); border: 1px solid color-mix(in srgb, var(--warn-border) 35%, transparent); color: var(--text); max-width: 640px; font-size: 14.5px; }
.refresh-note { max-width: 1120px; margin: 0 auto; padding: 8px 24px; font-size: 14px; color: var(--text-3); }

.num { flex: none; width: 22px; height: 22px; border-radius: 50%; display: inline-grid; place-items: center; font-size: 11.5px; font-weight: 600;
  color: var(--text-3); border: 1px solid var(--border-strong); background: var(--surface); }
.is-done .num { background: var(--done); border-color: var(--done); color: transparent; position: relative; }
.is-done .num::after { content: ''; position: absolute; width: 8px; height: 4px; border-left: 1.8px solid #fff; border-bottom: 1.8px solid #fff; transform: rotate(-45deg) translate(1px, -1px); }
.progress { height: 4px; background: var(--border); border-radius: 99px; overflow: hidden; }
.progress span { display: block; height: 100%; width: 0; background: var(--accent); border-radius: 99px; transition: width .4s ease; }
.progress-text { font-size: 12.5px; color: var(--text-3); margin: 8px 0 0; }

/* ---------- lesson layout ---------- */
.lesson-layout { max-width: 1400px; margin: 0 auto; display: grid; grid-template-columns: 272px minmax(0, 1fr) 224px; gap: 48px; padding: 0 24px; }
.sidebar { position: sticky; top: var(--topbar); align-self: start; height: calc(100vh - var(--topbar)); overflow: auto; padding: 28px 16px 40px 0; border-right: 1px solid var(--border); }
.back { display: inline-flex; align-items: center; gap: 4px; font-size: 13.5px; color: var(--text-3); text-decoration: none; margin: 0 0 20px -3px; }
.back:hover { color: var(--text); }
.side-title { font-size: 15px; font-weight: 600; line-height: 1.35; margin: 0 0 14px; letter-spacing: -.01em; }
.side-lessons { list-style: none; padding: 0; margin: 24px 0 0; display: grid; gap: 1px; }
.side-lessons a { display: flex; gap: 11px; align-items: flex-start; padding: 8px 10px; border-radius: var(--radius-sm); color: var(--text-2); text-decoration: none; font-size: 14px; line-height: 1.45; }
.side-lessons a:hover { background: var(--bg-subtle); color: var(--text); }
.side-lessons a[aria-current="page"] { background: var(--bg-subtle); color: var(--text); font-weight: 500; }
.side-lessons a[aria-current="page"] .num { border-color: var(--text); color: var(--text); }
.side-lessons .lt { padding-top: 1px; }

.lesson { padding: 40px 0 96px; min-width: 0; max-width: 760px; }
.menu-btn { display: none; margin-bottom: 20px; }
.crumbs { display: flex; gap: 8px; align-items: center; margin: 0 0 12px; font-size: 13.5px; color: var(--text-3); }
.crumbs a { color: var(--text-2); text-decoration: none; }
.crumbs a:hover { color: var(--text); }
.lesson-head h1 { font-size: clamp(28px, 3.6vw, 36px); line-height: 1.15; letter-spacing: -.03em; margin: 0 0 14px; }
.lesson-meta { display: flex; flex-wrap: wrap; gap: 6px 22px; font-size: 13.5px; color: var(--text-2); }
.lesson-meta > span { display: inline-flex; align-items: center; gap: 7px; }
.lesson-meta .icon { color: var(--text-3); width: 15px; height: 15px; }
.lesson-head { padding-bottom: 24px; margin-bottom: 8px; border-bottom: 1px solid var(--border); }

.toc { position: sticky; top: var(--topbar); align-self: start; padding: 40px 0; max-height: calc(100vh - var(--topbar)); overflow: auto; }
.toc-title { font-size: 12.5px; font-weight: 600; color: var(--text); margin: 0 0 10px; }
.toc ol { list-style: none; padding: 0; margin: 0; }
.toc a { display: block; padding: 5px 0; color: var(--text-3); text-decoration: none; font-size: 13px; line-height: 1.45; }
.toc a:hover { color: var(--text); }
.toc a.active { color: var(--accent); }
.kbd-hint { margin-top: 28px; padding-top: 16px; border-top: 1px solid var(--border); font-size: 12px; color: var(--text-3); display: flex; align-items: center; gap: 4px; }
kbd { font: 500 11px var(--mono); min-width: 20px; height: 20px; display: inline-grid; place-items: center; border: 1px solid var(--border-strong); border-radius: 5px; background: var(--surface); color: var(--text-2); }
.kbd-hint kbd:last-of-type { margin-right: 6px; }

/* ---------- prose ---------- */
.prose { font-size: 16px; line-height: 1.72; color: var(--text); }
.prose h2 { font-size: 21px; letter-spacing: -.02em; margin: 48px 0 12px; line-height: 1.3; }
.prose h3 { font-size: 17px; margin: 32px 0 8px; }
.prose p { margin: 12px 0; }
.prose ul, .prose ol { padding-left: 1.3em; }
.prose li { margin: 6px 0; }
.prose li::marker { color: var(--text-3); }
.prose strong { font-weight: 600; }
.prose code { font: 500 .86em var(--mono); background: var(--code-bg); border: 1px solid var(--border); padding: 1px 5px; border-radius: 5px; white-space: break-spaces; }
.prose pre { position: relative; background: var(--code-bg); border: 1px solid var(--border); border-radius: var(--radius); padding: 14px 16px; padding-right: 76px; overflow: auto; font-size: 13.5px; line-height: 1.65; }
.prose pre code { background: none; border: 0; padding: 0; white-space: pre-wrap; }
.copy-btn { position: absolute; top: 8px; right: 8px; font: 500 12px var(--font); color: var(--text-2); background: var(--surface); border: 1px solid var(--border-strong); border-radius: 6px; padding: 4px 9px; cursor: pointer; }
.copy-btn:hover { color: var(--text); }
.copy-btn.ok { color: var(--done); }
.code-copy { cursor: copy; }
.code-copy.copied { border-color: var(--done); }
.prose hr { border: 0; border-top: 1px solid var(--border); margin: 40px 0; }

/* numbered steps with completion toggles */
.prose ol.steps { list-style: none; padding-left: 0; counter-reset: none; }
.prose ol.steps > li { position: relative; padding: 4px 0 4px 44px; margin: 14px 0; }
.step-check { position: absolute; left: 0; top: 3px; width: 28px; height: 28px; border-radius: 50%; border: 1px solid var(--border-strong); background: var(--surface);
  color: var(--text-2); font: 600 12.5px var(--font); cursor: pointer; display: grid; place-items: center; padding: 0; transition: background .15s, border-color .15s, color .15s; }
.step-check:hover { border-color: var(--text-2); color: var(--text); }
.prose ol.steps > li.done > .step-check { background: var(--done); border-color: var(--done); color: transparent; }
.prose ol.steps > li.done > .step-check::after { content: ''; position: absolute; width: 10px; height: 5px; border-left: 2px solid #fff; border-bottom: 2px solid #fff; transform: rotate(-45deg) translate(1px, -1px); }
.prose ol.steps > li.done > p:first-of-type { color: var(--text-3); }
.prose ol.steps > li > p:first-of-type { margin-top: 0; }
.prose ol.steps ol, .prose ol.steps ul { margin: 8px 0; }

.checklist { list-style: none; padding: 0 !important; border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.checklist li { margin: 0; border-top: 1px solid var(--border); }
.checklist li:first-child { border-top: 0; }
.checklist label { display: flex; gap: 12px; align-items: flex-start; padding: 12px 16px; cursor: pointer; }
.checklist label:hover { background: var(--bg-subtle); }
.checklist input { width: 16px; height: 16px; margin-top: 4px; accent-color: var(--done); flex: none; }
.checklist li.done label { color: var(--text-3); }

/* figures */
.prose figure { margin: 20px 0 24px; }
.zoom { display: block; width: 100%; padding: 0; border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; background: var(--bg-subtle); cursor: zoom-in; }
.zoom img { display: block; width: 100%; height: auto; }
.prose figcaption { font-size: 13px; color: var(--text-3); margin-top: 8px; }
.lightbox { position: fixed; inset: 0; z-index: 100; background: rgba(10, 10, 12, .86); display: grid; place-items: center; padding: 32px; cursor: zoom-out; }
.lightbox img { max-width: 100%; max-height: 100%; border-radius: 6px; background: #fff; }
.lightbox-close { position: absolute; top: 16px; right: 16px; color: #fff; }
.lightbox-close:hover { background: rgba(255,255,255,.1); color: #fff; }

/* call-outs */
.callout { margin: 20px 0; padding: 12px 16px; border-left: 3px solid; border-radius: 0 var(--radius-sm) var(--radius-sm) 0; }
.callout p { margin: 0; }
.callout-info { background: var(--note-bg); border-color: var(--note-border); }
.callout-warn { background: var(--warn-bg); border-color: var(--warn-border); }
.prose ol.steps > li .callout { margin: 12px 0; }

/* troubleshooting */
.trouble { border-top: 1px solid var(--border); }
.trouble:last-of-type { border-bottom: 1px solid var(--border); }
.trouble summary { cursor: pointer; padding: 14px 0; font-weight: 500; list-style: none; display: flex; justify-content: space-between; gap: 16px; }
.trouble summary::-webkit-details-marker { display: none; }
.trouble summary::after { content: ''; flex: none; width: 7px; height: 7px; margin-top: 7px; border-right: 1.6px solid var(--text-3); border-bottom: 1.6px solid var(--text-3); transform: rotate(45deg); transition: transform .15s; }
.trouble[open] summary::after { transform: rotate(-135deg); margin-top: 10px; }
.trouble p { margin: 0; padding: 0 0 16px; color: var(--text-2); }

/* download */
.download { display: flex; align-items: center; gap: 14px; padding: 14px 16px; margin: 16px 0; border-radius: var(--radius); border: 1px solid var(--border); background: var(--surface); box-shadow: var(--shadow-sm); }
.download-icon { width: 38px; height: 38px; border-radius: 8px; display: grid; place-items: center; background: var(--bg-subtle); border: 1px solid var(--border); color: var(--text-2); flex: none; }
.download-icon .icon { width: 18px; height: 18px; }
.download-text { flex: 1; display: grid; min-width: 0; }
.download-text strong { font-weight: 600; font-size: 14.5px; overflow-wrap: anywhere; }
.download-text span { font-size: 13px; color: var(--text-3); }
.table-wrap { overflow-x: auto; }
table { border-collapse: collapse; width: 100%; font-size: 14.5px; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); }

/* completion + pager */
.complete-row { margin: 56px 0 24px; padding: 18px 20px; border-radius: var(--radius); border: 1px solid var(--border); background: var(--bg-subtle); display: flex; align-items: center; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
.complete-row div { display: grid; }
.complete-row strong { font-weight: 600; }
.complete-row span { color: var(--text-3); font-size: 14px; }
.complete-row.is-done .mark-done { background: var(--done); color: #fff; }
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.pager-link { display: grid; gap: 4px; padding: 14px 16px; border: 1px solid var(--border); border-radius: var(--radius); text-decoration: none; color: var(--text); transition: border-color .15s; }
.pager-link:hover { border-color: var(--border-strong); background: var(--bg-subtle); }
.pager-link span { font-size: 12.5px; color: var(--text-3); display: inline-flex; align-items: center; gap: 4px; }
.pager-link .icon { width: 14px; height: 14px; }
.pager-link strong { font-size: 14.5px; font-weight: 500; }
.pager-link.next { text-align: right; }
.pager-link.next span { justify-content: flex-end; }

/* watermark */
.watermark { position: fixed; inset: 0; pointer-events: none; z-index: 20; opacity: .045; background-repeat: repeat; background-size: 420px 220px; }

/* ---------- message pages ---------- */
.message { min-height: calc(100vh - var(--topbar)); display: grid; place-items: center; padding: 48px 24px; }
.message-card { max-width: 520px; text-align: center; }
.message-card h1 { font-size: 28px; margin: 0 0 12px; letter-spacing: -.025em; }
.message-card .lead { font-size: 16px; margin: 0 auto 28px; }
.message-actions { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; }

/* ---------- admin ---------- */
.admin-panel { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); padding: 22px 24px; margin-bottom: 20px; }
.admin-panel h2 { font-size: 16px; margin: 0 0 4px; letter-spacing: -.01em; }
.admin-panel .sub { color: var(--text-3); font-size: 14px; margin: 0 0 18px; }
.admin-row { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; justify-content: space-between; }
.admin-row .sub { margin: 0; }
.matrix-wrap { overflow-x: auto; margin: 0 -24px; padding: 0 24px; }
.matrix { border-collapse: collapse; width: 100%; min-width: 560px; }
.matrix th, .matrix td { padding: 14px 12px; border-bottom: 1px solid var(--border); text-align: center; vertical-align: middle; }
.matrix tr:last-child th, .matrix tr:last-child td { border-bottom: 0; }
.matrix th:first-child, .matrix td:first-child { text-align: left; position: sticky; left: 0; background: var(--surface); padding-left: 0; }
.matrix thead th { font-size: 13px; color: var(--text); font-weight: 600; }
.matrix thead th .price { display: block; color: var(--text-3); font-weight: 400; font-size: 12px; margin-top: 2px; }
.matrix tbody th { font-weight: 500; font-size: 14.5px; }
.matrix tbody th small { display: block; font-weight: 400; color: var(--text-3); font-size: 12.5px; }
.matrix tr.default-row th { font-weight: 600; }
.matrix input[type=checkbox] { width: 17px; height: 17px; accent-color: var(--primary); cursor: pointer; }
.matrix input[type=checkbox]:disabled { cursor: not-allowed; opacity: .45; }
.matrix .follow { font-size: 12.5px; color: var(--text-2); display: inline-flex; gap: 6px; align-items: center; margin-top: 6px; font-weight: 400; cursor: pointer; }
.matrix .follow input { width: 14px; height: 14px; }
.admin-status { color: var(--text-3); font-size: 14px; margin: 0; }
.admin-status.ok { color: var(--done); }
.admin-status.err { color: var(--danger); }
.summary { display: grid; gap: 12px; grid-template-columns: repeat(auto-fill, minmax(min(100%, 220px), 1fr)); }
.summary div { border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 12px 14px; }
.summary strong { display: block; margin-bottom: 4px; font-weight: 600; font-size: 14px; }
.summary em { font-style: normal; color: var(--accent); font-size: 13px; }
.summary span { color: var(--text-2); font-size: 13.5px; }
.save-bar { position: sticky; bottom: 0; z-index: 10; display: flex; flex-wrap: wrap; gap: 14px; align-items: center; justify-content: flex-end; padding: 16px 0 24px; background: linear-gradient(transparent, var(--bg) 35%); }
.save-bar .dirty { color: var(--warn-text); font-size: 14px; margin-right: auto; }
.empty-tiers { margin: 0; padding: 14px 16px; border-radius: var(--radius-sm); background: var(--note-bg); border-left: 3px solid var(--note-border); font-size: 14.5px; }

/* ---------- responsive ---------- */
@media (max-width: 1180px) {
  .lesson-layout { grid-template-columns: 256px minmax(0, 1fr); gap: 40px; }
  .toc { display: none; }
}
@media (max-width: 860px) {
  .lesson-layout { grid-template-columns: minmax(0, 1fr); padding: 0 16px; gap: 0; }
  .sidebar { position: fixed; top: var(--topbar); left: 0; bottom: 0; width: min(320px, 86vw); height: auto; z-index: 40; background: var(--bg);
    padding: 20px 16px; transform: translateX(-102%); transition: transform .2s ease; box-shadow: 0 10px 30px rgba(0,0,0,.12); }
  .sidebar.open { transform: none; }
  .menu-btn { display: inline-flex; }
  .lesson { padding-top: 24px; }
  .pager { grid-template-columns: 1fr; }
  .pager-link.next { text-align: left; }
  .pager-link.next span { justify-content: flex-start; }
  .topbar-inner, .hero, .section, .page-head, .refresh-note, .footer-inner { padding-left: 16px; padding-right: 16px; }
  .hero { padding-top: 56px; }
  .member-name { display: none; }
  .download { flex-wrap: wrap; }
}
@media (max-width: 480px) {
  .brand-name { display: none; }
}
@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }
@media print {
  .topbar, .sidebar, .toc, .pager, .complete-row, .menu-btn, .watermark { display: none !important; }
  .lesson-layout { display: block; }
}