:root,
[data-theme="dark"] {
  color-scheme: dark;
  --page: #0b1120;
  --sidebar: #101827;
  --surface: #151e30;
  --raised: #1e293b;
  --code: #0f172a;
  --border: #334155;
  --text: #f1f5f9;
  --secondary: #cbd5e1;
  --muted: #94a3b8;
  --accent: #22d3ee;
  --focus: #818cf8;
  --success: #34d399;
  --warning: #fbbf24;
  --error: #fb7185;
  --keyword: #f472b6;
  --type: #67e8f9;
  --function: #a3e635;
  --string: #fda4af;
  --number: #fcd34d;
  --comment: #94a3b8;
  --attribute: #c4b5fd;
  --operator: #fdba74;
}
[data-theme="light"] {
  color-scheme: light;
  --page: #f8fafc;
  --sidebar: #f1f5f9;
  --surface: #fff;
  --raised: #f8fafc;
  --code: #f1f5f9;
  --border: #e2e8f0;
  --text: #0f172a;
  --secondary: #475569;
  --muted: #526173;
  --accent: #0e7490;
  --focus: #4f46e5;
  --success: #047857;
  --warning: #b45309;
  --error: #be123c;
  --keyword: #be185d;
  --type: #0369a1;
  --function: #15803d;
  --string: #b91c1c;
  --number: #b45309;
  --comment: #5b6778;
  --attribute: #7c3aed;
  --operator: #c2410c;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 92px; }
body { margin: 0; background: var(--page); color: var(--text); font: 16px/1.65 -apple-system, BlinkMacSystemFont, "SF Pro Text", system-ui, sans-serif; }
a { color: var(--accent); text-decoration-thickness: .08em; text-underline-offset: .17em; }
a:hover { text-decoration-thickness: .14em; }
button, input, select { font: inherit; }
button, select { color: var(--text); }
button:focus-visible, a:focus-visible, input:focus-visible, select:focus-visible, textarea:focus-visible, summary:focus-visible { outline: 3px solid var(--focus); outline-offset: 3px; }
.skip-link { position: fixed; z-index: 60; top: 8px; left: 8px; padding: 9px 13px; transform: translateY(-160%); border-radius: 7px; background: var(--raised); color: var(--text); }
.skip-link:focus { transform: translateY(0); }
.site-header { position: sticky; z-index: 20; top: 0; display: flex; align-items: center; gap: 18px; min-height: 64px; padding: 8px clamp(14px, 3vw, 36px); border-bottom: 1px solid var(--border); background: color-mix(in srgb, var(--page) 94%, transparent); backdrop-filter: blur(16px); }
.brand { display: inline-flex; flex: 0 0 auto; align-items: center; gap: 10px; color: var(--text); font-weight: 750; text-decoration: none; }
.brand-mark { position: relative; display: block; flex: 0 0 34px; width: 34px; height: 34px; overflow: hidden; border-radius: 7px; background: #0b1120; }
.brand-mark img { position: absolute; top: -10px; left: -18px; width: 70px; height: 70px; max-width: none; }
.primary-nav { display: flex; flex: 1 1 auto; align-items: center; gap: clamp(8px, 1.6vw, 22px); min-width: 0; white-space: nowrap; }
.primary-nav a { flex: 0 0 auto; color: var(--secondary); font-size: 13px; text-decoration: none; }
.primary-nav a:hover { color: var(--text); }
.header-tools { display: flex; flex: 0 0 auto; align-items: center; gap: 8px; }
.theme-toggle, .nav-toggle, .toolbar-button { min-height: 38px; padding: 6px 10px; border: 1px solid var(--border); border-radius: 8px; background: var(--surface); cursor: pointer; white-space: nowrap; }
.nav-toggle { display: none; }
.search-box { position: relative; width: clamp(150px, 20vw, 260px); }
.search-input { width: 100%; min-height: 38px; padding: 7px 32px 7px 10px; border: 1px solid var(--border); border-radius: 8px; background: var(--code); color: var(--text); }
.search-shortcut { position: absolute; top: 7px; right: 8px; color: var(--muted); font-size: 12px; }
.search-results { position: absolute; z-index: 30; top: calc(100% + 7px); right: 0; left: 0; max-height: min(65vh, 520px); overflow: auto; padding: 6px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface); box-shadow: 0 14px 45px #0005; }
.search-results[hidden] { display: none; }
.search-result { display: block; padding: 9px 10px; border-radius: 7px; color: var(--text); text-decoration: none; }
.search-result:hover, .search-result:focus-visible { background: var(--raised); }
.search-result-title { display: block; font-weight: 650; }
.search-result-context, .search-empty { display: block; margin-top: 2px; color: var(--muted); font-size: 12px; }
.search-status { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); }
.page-shell { display: grid; grid-template-columns: 276px minmax(0, 1fr) 220px; min-height: calc(100vh - 64px); }
.page-shell.no-sidebar { grid-template-columns: minmax(0, 1fr); }
.page-shell.no-outline { grid-template-columns: 276px minmax(0, 1fr); }
.page-shell.no-outline.no-sidebar { grid-template-columns: minmax(0, 1fr); }
.left-rail, .right-rail { position: sticky; top: 64px; align-self: start; height: calc(100vh - 64px); overflow: auto; padding: 18px 14px 28px; background: var(--sidebar); }
.left-rail { border-right: 1px solid var(--border); }
.right-rail { border-left: 1px solid var(--border); }
body.nav-open { overflow: hidden; }
.rail-label, .eyebrow { display: block; margin: 10px 4px 7px; color: var(--muted); font-size: 11px; font-weight: 750; letter-spacing: .1em; text-transform: uppercase; }
.domain-picker { width: 100%; padding: 8px; border: 1px solid var(--border); border-radius: 7px; background: var(--code); }
.topic-group { margin: 3px 0; }
.topic-group > summary { padding: 7px 8px; border-radius: 6px; color: var(--secondary); font-size: 13px; font-weight: 650; cursor: pointer; }
.topic-group > summary:hover { background: var(--raised); color: var(--text); }
.topic-links { display: grid; gap: 2px; margin: 2px 0 8px 9px; padding-left: 8px; border-left: 1px solid var(--border); }
.topic-link { display: block; padding: 5px 7px; border-radius: 5px; color: var(--secondary); font-size: 12px; line-height: 1.4; text-decoration: none; }
.topic-link:hover, .topic-link[aria-current="page"] { background: var(--raised); color: var(--text); }
.topic-link[aria-current="page"] { box-shadow: inset 2px 0 0 var(--focus); }
.sidebar-saved { margin-top: 20px; padding-top: 12px; border-top: 1px solid var(--border); }
.sidebar-saved h2 { margin: 0 4px 7px; border: 0; color: var(--muted); font-size: 11px; letter-spacing: .1em; text-transform: uppercase; }
.saved-links { display: grid; gap: 3px; }
.saved-links a { overflow: hidden; padding: 5px 7px; border-radius: 5px; color: var(--secondary); font-size: 12px; text-overflow: ellipsis; white-space: nowrap; }
.saved-links a:hover { background: var(--raised); color: var(--text); }
.main-content { min-width: 0; width: min(100%, 1000px); padding: clamp(22px, 4vw, 54px) clamp(18px, 4vw, 62px) 80px; margin: 0 auto; }
.breadcrumbs { position: sticky; z-index: 10; top: 64px; margin: -8px 0 14px; padding: 8px 0; background: color-mix(in srgb, var(--page) 96%, transparent); color: var(--muted); font-size: 13px; backdrop-filter: blur(12px); }
.breadcrumbs a { color: var(--secondary); }
.breadcrumb-section { color: var(--muted); }
.lesson-meta { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin: 0 0 22px; }
.meta-chip { padding: 4px 8px; border: 1px solid var(--border); border-radius: 99px; background: var(--surface); color: var(--secondary); font-size: 12px; }
.page-summary { max-width: 760px; color: var(--secondary); font-size: 18px; }
.lesson-actions { display: flex; flex-wrap: wrap; gap: 7px; margin: 18px 0 28px; }
.status-message { min-height: 1.4em; color: var(--muted); font-size: 12px; }
.article-body { min-width: 0; }
h1, h2, h3, h4, h5, h6 { line-height: 1.28; letter-spacing: -.018em; scroll-margin-top: 88px; }
h1 { margin: 0 0 15px; font-size: clamp(30px, 4vw, 44px); }
h2 { margin: 38px 0 10px; padding-bottom: 7px; border-bottom: 1px solid var(--border); font-size: 25px; }
h3 { margin: 28px 0 8px; font-size: 19px; }
h4 { margin: 22px 0 7px; font-size: 16px; }
p { margin: 12px 0; }
ul, ol { padding-left: 26px; }
li { margin: 4px 0; }
blockquote { margin: 17px 0; padding: 10px 15px; border-left: 3px solid var(--accent); border-radius: 0 7px 7px 0; background: var(--raised); color: var(--secondary); }
code.inline-code { padding: 2px 5px; border: 1px solid var(--border); border-radius: 5px; background: var(--raised); color: var(--warning); font: .92em ui-monospace, SFMono-Regular, Menlo, monospace; }
.code-card { margin: 17px 0 23px; overflow: hidden; border: 1px solid var(--border); border-radius: 10px; background: var(--code); }
.code-toolbar { display: flex; align-items: center; justify-content: space-between; padding: 7px 11px; border-bottom: 1px solid var(--border); background: var(--surface); color: var(--muted); font: 11px ui-monospace, SFMono-Regular, Menlo, monospace; }
.copy-button { padding: 4px 8px; border: 1px solid var(--border); border-radius: 5px; background: var(--raised); color: var(--secondary); cursor: pointer; font: 12px system-ui, sans-serif; }
.copy-status:not(.sr-only) { color: var(--muted); font: 12px system-ui, sans-serif; }
pre { margin: 0; padding: 12px 0 14px; overflow: auto; tab-size: 4; }
pre code { display: block; color: var(--text); white-space: pre; font: 13px/1.65 ui-monospace, "SF Mono", Menlo, Monaco, monospace; }
.line { display: block; min-height: 1.65em; padding-right: 16px; counter-increment: line; }
pre code { counter-reset: line; }
.line::before { display: inline-block; width: 44px; margin-right: 14px; padding-right: 10px; border-right: 1px solid var(--border); color: var(--muted); content: counter(line); text-align: right; user-select: none; }
.tok-keyword { color: var(--keyword); }
.tok-type { color: var(--type); }
.tok-string { color: var(--string); }
.tok-comment { color: var(--comment); font-style: italic; }
.tok-number, .tok-literal { color: var(--number); }
.tok-attribute, .tok-directive { color: var(--attribute); }
.tok-function { color: var(--function); }
.tok-operator { color: var(--operator); }
.table-wrap { overflow: auto; margin: 15px 0 23px; }
table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { padding: 9px 11px; border: 1px solid var(--border); text-align: left; vertical-align: top; }
th { background: var(--raised); color: var(--focus); }
tr:nth-child(even) td { background: color-mix(in srgb, var(--sidebar) 55%, var(--surface)); }
hr { margin: 25px 0; border: 0; border-top: 1px solid var(--border); }
.lesson-footer { display: flex; justify-content: space-between; gap: 12px; margin-top: 46px; padding-top: 20px; border-top: 1px solid var(--border); }
.lesson-footer a, .card, .path-card { padding: 13px; border: 1px solid var(--border); border-radius: 9px; background: var(--surface); }
.lesson-footer a { flex: 1; color: var(--secondary); text-decoration: none; }
.lesson-footer a:hover, .card:hover, .path-card:hover { border-color: var(--focus); }
.card-grid, .path-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 245px), 1fr)); gap: 12px; margin: 17px 0 28px; }
.card { display: block; color: var(--text); text-decoration: none; }
.card h2, .card h3, .path-card h3 { margin: 0 0 6px; padding: 0; border: 0; font-size: 17px; }
.card p, .path-card p { margin: 6px 0 0; color: var(--secondary); font-size: 14px; }
.hero { display: grid; grid-template-columns: minmax(0, 1fr) minmax(180px, 280px); align-items: center; gap: clamp(20px, 4vw, 42px); padding: clamp(22px, 5vw, 52px); border: 1px solid var(--border); border-radius: 16px; background: radial-gradient(ellipse at top right, #22d3ee22, transparent 56%), linear-gradient(135deg, var(--surface), var(--page)); }
.hero-copy { min-width: 0; }
.hero-logo { display: block; width: 100%; height: auto; border-radius: 18px; }
.hero h1 { max-width: 800px; font-size: clamp(38px, 6vw, 64px); }
.tagline { margin: 4px 0 0; color: var(--secondary); font-size: clamp(19px, 2vw, 24px); }
.hero-actions { display: flex; flex-wrap: wrap; gap: 9px; margin-top: 21px; }
.primary-action { padding: 10px 14px; border: 1px solid var(--focus); border-radius: 8px; background: var(--raised); color: var(--text); text-decoration: none; font-weight: 650; }
.overview-section { margin-top: 40px; }
.overview-section > h2 { margin-top: 0; }
.learning-page .main-content { width: min(100%, 1120px); }
.learning-hero { position: relative; overflow: hidden; padding: clamp(24px, 3vw, 34px); border: 1px solid var(--border); border-radius: 22px; background: radial-gradient(circle at 90% 12%, color-mix(in srgb, var(--focus) 22%, transparent), transparent 40%), linear-gradient(135deg, var(--surface), var(--page)); }
.learning-hero::after { position: absolute; top: -58px; right: -46px; width: 230px; height: 230px; border: 1px solid color-mix(in srgb, var(--focus) 38%, transparent); border-radius: 50%; box-shadow: 0 0 0 34px color-mix(in srgb, var(--focus) 5%, transparent), 0 0 0 74px color-mix(in srgb, var(--focus) 4%, transparent); content: ""; pointer-events: none; }
.learning-hero .eyebrow { margin: 0 0 12px; color: var(--accent); }
.learning-hero h1 { position: relative; z-index: 1; margin-bottom: 8px; font-size: clamp(38px, 4vw, 48px); }
.learning-hero p { position: relative; z-index: 1; max-width: 690px; margin: 0; color: var(--secondary); font-size: clamp(16px, 1.7vw, 18px); line-height: 1.5; }
.learning-hero-tags { position: relative; z-index: 1; display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
.learning-hero-tags span { padding: 5px 11px; border: 1px solid var(--border); border-radius: 999px; background: color-mix(in srgb, var(--surface) 86%, transparent); color: var(--secondary); font-size: 12px; font-weight: 650; }
.learning-page #learning-status { margin: 10px 2px 0; }
.learning-dashboard { display: grid; gap: 32px; margin-top: 20px; }
.learning-dashboard > .overview-section { margin-top: 0; }
.contribute-page .main-content { width: min(100%, 960px); }
.contribution-form { display: grid; gap: 9px; max-width: 760px; }
.contribution-form label, .contribution-card label { color: var(--secondary); font-weight: 650; }
.contribution-form input, .contribution-form select, .contribution-form textarea, .contribution-review-note { width: 100%; min-width: 0; padding: 10px 12px; border: 1px solid var(--border); border-radius: 8px; background: var(--surface); color: var(--text); }
.contribution-form textarea, .contribution-review-note { resize: vertical; line-height: 1.5; }
.contribution-form .field-help { margin-top: -5px; color: var(--muted); font-size: 13px; }
.contribution-form .primary-action { justify-self: start; margin-top: 8px; cursor: pointer; }
#admin-review-link-slot { margin-top: 28px; }
.contribution-list { display: grid; gap: 16px; margin: 18px 0; }
.contribution-card { min-width: 0; padding: clamp(16px, 3vw, 22px); border: 1px solid var(--border); border-radius: 12px; background: var(--surface); }
.contribution-card h3 { margin: 0 0 5px; }
.contribution-meta { margin: 0 0 10px; color: var(--muted); font-size: 13px; }
.contribution-status { display: inline-block; padding: 2px 9px; border: 1px solid var(--border); border-radius: 99px; color: var(--secondary); font-size: 12px; font-weight: 700; text-transform: capitalize; }
.contribution-status.status-approved { color: var(--success); }
.contribution-status.status-rejected { color: var(--error); }
.contribution-body, .contribution-draft pre { max-height: 400px; overflow: auto; padding: 12px; border: 1px solid var(--border); border-radius: 8px; background: var(--code); color: var(--text); white-space: pre-wrap; overflow-wrap: anywhere; font: 13px/1.6 ui-monospace, SFMono-Regular, Menlo, monospace; }
.contribution-draft { margin-top: 12px; }
.contribution-draft summary { cursor: pointer; }
.contribution-card > .toolbar-button { margin: 12px 0; }
.contribution-card label { display: grid; gap: 7px; margin-top: 16px; }
.contribution-note { padding: 8px 12px; border-left: 3px solid var(--focus); background: var(--raised); overflow-wrap: anywhere; }
.contribution-review-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
.contribution-review-actions button { cursor: pointer; }
.contribution-review-actions button:disabled, .contribution-form button:disabled { opacity: .6; cursor: wait; }
.learning-account > h2 { margin: 0 0 6px; padding: 0; border: 0; font-size: clamp(25px, 3vw, 30px); }
.account-description { max-width: 760px; margin: 0; color: var(--secondary); }
.auth-shell { display: grid; grid-template-columns: minmax(0, .82fr) minmax(0, 1fr); overflow: hidden; margin-top: 22px; border: 1px solid var(--border); border-radius: 18px; background: var(--surface); box-shadow: 0 18px 42px #0002; }
.auth-shell[hidden] { display: none; }
.auth-promise { padding: clamp(24px, 3vw, 38px); border-right: 1px solid var(--border); background: radial-gradient(circle at 10% 0%, color-mix(in srgb, var(--accent) 13%, transparent), transparent 50%), var(--sidebar); }
.auth-promise .eyebrow { margin: 0 0 12px; color: var(--accent); }
.auth-promise h3 { max-width: 330px; margin: 0; font-size: clamp(27px, 3vw, 37px); }
.auth-promise > p { max-width: 340px; margin: 13px 0 27px; color: var(--secondary); }
.auth-promise ul { display: grid; gap: 16px; margin: 0; padding: 0; list-style: none; }
.auth-promise li { position: relative; display: grid; gap: 2px; margin: 0; padding-left: 23px; }
.auth-promise li::before { position: absolute; top: 9px; left: 0; width: 9px; height: 9px; border-radius: 50%; background: var(--accent); content: ""; }
.auth-promise li strong { font-size: 14px; }
.auth-promise li span { color: var(--secondary); font-size: 13px; }
.auth-panel { min-width: 0; padding: clamp(22px, 3vw, 34px); }
.auth-panel > h3 { margin: 24px 0 4px; font-size: 24px; }
.auth-panel > p:not(.announcement) { margin: 0; color: var(--secondary); font-size: 14px; }
.auth-mode-switch { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 4px; padding: 4px; border: 1px solid var(--border); border-radius: 11px; background: var(--page); }
.auth-mode-switch button { min-height: 42px; border: 1px solid transparent; border-radius: 8px; background: transparent; color: var(--secondary); cursor: pointer; font-weight: 700; }
.auth-mode-switch button[aria-pressed="true"] { border-color: var(--border); background: var(--raised); color: var(--text); box-shadow: 0 2px 8px #0002; }
.auth-mode-switch button:hover:not([aria-pressed="true"]) { color: var(--text); }
.auth-mode-switch button:disabled { cursor: wait; }
.auth-panel .social-actions { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 9px; margin: 22px 0 20px; }
.auth-panel .social-actions button { min-width: 0; min-height: 48px; padding: 9px 10px; border-radius: 9px; }
.auth-divider { display: flex; align-items: center; gap: 12px; color: var(--muted); font-size: 12px; white-space: nowrap; }
.auth-divider::before, .auth-divider::after { flex: 1; height: 1px; background: var(--border); content: ""; }
.auth-email-form { max-width: none; gap: 7px; margin: 17px 0 8px; }
.auth-email-form label { font-size: 13px; }
.auth-email-form input { min-height: 48px; margin-bottom: 6px; background: var(--page); }
.auth-email-form .field-help { margin: -4px 0 5px; }
.auth-email-form .auth-primary { min-height: 48px; margin-top: 5px; padding: 10px 16px; border: 1px solid var(--focus); border-radius: 9px; background: var(--focus); color: var(--page); cursor: pointer; font-weight: 750; }
.auth-email-form .auth-primary:hover { filter: brightness(1.08); }
.auth-email-form .auth-primary:disabled { opacity: .65; cursor: wait; }
.auth-feedback { margin: 9px 0 0; color: var(--secondary); font-size: 13px; }
.auth-feedback:empty { display: none; }
.auth-panel > .text-button { margin-top: 6px; font-size: 13px; }
.auth-panel > .announcement { margin: 12px 0 0; }
.learning-page.is-signed-in .profile-card { max-width: 760px; }
.right-rail h2 { margin: 0 0 12px; border: 0; font-size: 13px; }
.outline-list { display: grid; gap: 4px; }
.outline-list a { display: block; padding: 4px 6px; border-radius: 5px; color: var(--secondary); font-size: 12px; line-height: 1.4; text-decoration: none; }
.outline-list a[data-level="3"] { margin-left: 9px; }
.outline-list a[data-level="4"] { margin-left: 18px; }
.outline-list a:hover, .outline-list a[aria-current="location"] { background: var(--raised); color: var(--text); }
.domain-breadcrumb { color: var(--muted); font-size: 12px; }
.announcement { color: var(--muted); font-size: 13px; }
.practice-card { margin: 20px 0; padding: clamp(15px, 3vw, 24px); border: 1px solid var(--border); border-radius: 11px; background: var(--surface); }
.practice-controls, .practice-options { display: grid; gap: 9px; margin: 15px 0; }
.practice-controls { grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); }
.practice-controls label { display: grid; gap: 4px; color: var(--secondary); font-size: 13px; }
.practice-controls select { min-height: 38px; padding: 6px 8px; border: 1px solid var(--border); border-radius: 7px; background: var(--code); }
.practice-options label { display: flex; align-items: flex-start; gap: 9px; padding: 10px; border: 1px solid var(--border); border-radius: 7px; background: var(--raised); cursor: pointer; }
.practice-options input { margin-top: 5px; accent-color: var(--focus); }
.practice-option-result { display: block; margin: 4px 0 0 25px; color: var(--secondary); font-size: 13px; }
.practice-option-result.correct { color: var(--success); }
.practice-option-result.incorrect { color: var(--error); }
.practice-feedback { min-height: 1.5em; font-weight: 650; }
.learning-stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(135px, 1fr)); gap: 10px; margin: 16px 0 24px; }
.learning-stat { padding: 16px; border: 1px solid var(--border); border-radius: 9px; background: var(--surface); }
.learning-stat strong { display: block; font-size: 28px; line-height: 1.2; }
.learning-stat span { color: var(--secondary); font-size: 13px; }
.learning-columns { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 250px), 1fr)); gap: 20px; }
.learning-columns h3 { margin-top: 0; }
.learning-list { display: grid; gap: 8px; }
.learning-list a { display: block; padding: 10px 12px; border: 1px solid var(--border); border-radius: 8px; background: var(--surface); color: var(--text); text-decoration: none; }
.learning-list a:hover { border-color: var(--focus); }
.account-form { display: grid; gap: 8px; max-width: 440px; margin: 18px 0 10px; }
.account-form label { font-weight: 650; }
.account-form input, .account-form select, .account-form textarea { min-height: 42px; width: 100%; padding: 8px 10px; border: 1px solid var(--border); border-radius: 7px; background: var(--surface); color: var(--text); }
.account-form textarea { resize: vertical; }
.account-form input[type="file"] { min-height: 0; padding: 7px 0; border: 0; }
.account-actions { display: flex; flex-wrap: wrap; gap: 8px; margin: 10px 0; }
.account-actions button, .account-delete button { min-height: 40px; padding: 7px 12px; border: 1px solid var(--border); border-radius: 7px; background: var(--raised); color: var(--text); cursor: pointer; }
.account-actions button:hover, .account-delete button:hover { border-color: var(--focus); }
.social-actions { margin: 18px 0 12px; }
.social-actions button { flex: 1 1 160px; background: var(--surface); font-weight: 650; }
.social-actions button[disabled] { opacity: .55; cursor: not-allowed; }
.profile-card { max-width: 700px; margin: 25px 0; padding: 16px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface); }
.profile-card h3 { margin-top: 0; }
.profile-card .account-form { max-width: 480px; }
.profile-card .profile-form { max-width: 640px; }
.profile-fields { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; }
.profile-fields > div { display: grid; align-content: start; gap: 8px; min-width: 0; }
.profile-photo-row { display: flex; align-items: center; gap: 18px; margin-bottom: 12px; }
.profile-photo-row > div { min-width: 0; flex: 1; }
.profile-photo-row label { display: block; margin-bottom: 6px; }
.profile-photo-preview, .profile-photo-placeholder { flex: 0 0 88px; width: 88px; height: 88px; border: 1px solid var(--border); border-radius: 50%; object-fit: cover; }
.profile-photo-preview[hidden], .profile-photo-placeholder[hidden] { display: none; }
.profile-photo-placeholder { display: grid; place-items: center; background: var(--raised); color: var(--muted); font-size: 40px; }
.profile-photo-row button { margin-top: 4px; }
.field-help, .optional { color: var(--muted); font-weight: 400; font-size: 13px; }
.field-help { margin: 6px 0 0; }
.profile-card .account-form + .account-form { margin-top: 24px; padding-top: 20px; border-top: 1px solid var(--border); }
.profile-card button { justify-self: start; min-height: 40px; padding: 7px 12px; border: 1px solid var(--border); border-radius: 7px; background: var(--raised); color: var(--text); cursor: pointer; }
@media (max-width: 540px) { .profile-fields { grid-template-columns: 1fr; } .profile-photo-row { align-items: flex-start; } }
.text-button { padding: 0; border: 0; background: transparent; color: var(--accent); cursor: pointer; text-decoration: underline; }
.merge-choice { max-width: 700px; margin: 18px 0; padding: 16px; border: 1px solid var(--warning); border-radius: 9px; background: var(--surface); }
.merge-choice h3 { margin-top: 0; }
.account-delete { max-width: 700px; margin-top: 26px; padding-top: 14px; border-top: 1px solid var(--border); }
.account-delete summary { cursor: pointer; }
.site-footer { display: flex; flex-wrap: wrap; gap: 12px 20px; padding: 22px clamp(14px, 3vw, 36px); border-top: 1px solid var(--border); color: var(--muted); font-size: 13px; }
.site-footer a { color: var(--secondary); }
.footer-button { padding: 0; border: 0; background: none; color: var(--secondary); cursor: pointer; font-size: inherit; text-decoration: underline; text-underline-offset: .17em; }
.analytics-consent { position: fixed; z-index: 70; right: 16px; bottom: 16px; left: 16px; display: flex; align-items: center; justify-content: space-between; gap: 18px; max-width: 740px; margin: 0 auto; padding: 14px 18px; border: 1px solid var(--border); border-radius: 10px; background: var(--surface); box-shadow: 0 12px 36px #0006; color: var(--text); font-size: 14px; }
.analytics-consent[hidden] { display: none; }
.analytics-consent p { margin: 0; }
.analytics-consent-actions { display: flex; flex: 0 0 auto; gap: 8px; }
.analytics-consent-actions button { min-height: 38px; padding: 6px 10px; border: 1px solid var(--border); border-radius: 7px; background: var(--raised); color: var(--text); cursor: pointer; }
.analytics-consent-actions button:first-child { border-color: var(--focus); }
@media (max-width: 620px) { .analytics-consent { flex-direction: column; align-items: stretch; } .analytics-consent-actions { justify-content: flex-end; } }
@media (max-width: 760px) {
  .auth-shell { grid-template-columns: 1fr; }
  .auth-promise { border-right: 0; border-bottom: 1px solid var(--border); }
  .auth-promise ul { grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; }
  .auth-panel { padding: 23px; }
}
@media (max-width: 540px) {
  .learning-hero { padding: 24px 21px; }
  .learning-hero::after { right: -130px; }
  .learning-hero-tags { display: none; }
  .auth-panel { order: -1; padding: 20px; }
  .auth-promise { padding: 22px; border-top: 1px solid var(--border); border-bottom: 0; }
  .auth-promise > p { margin-bottom: 16px; }
  .auth-promise ul { grid-template-columns: 1fr; gap: 11px; }
  .auth-panel .social-actions { grid-template-columns: 1fr; }
}
@media (max-width: 360px) { .auth-mode-switch button { font-size: 13px; } }
.sr-only { position: absolute !important; width: 1px; height: 1px; padding: 0; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }
.article-section.is-hidden-in-recap { display: none; }
.focus-mode .page-shell { grid-template-columns: minmax(0, 1fr); }
.focus-mode .left-rail, .focus-mode .right-rail { display: none; }
.focus-mode .main-content { max-width: 900px; }
body.nav-open::after { position: fixed; z-index: 29; inset: 64px 0 0; background: #02061799; content: ""; }
@media (min-width: 821px) and (max-width: 1450px) {
  .site-header { display: grid; grid-template-columns: minmax(0, 1fr) auto; grid-template-rows: 38px 20px; gap: 6px 16px; min-height: 84px; }
  .brand { grid-column: 1; grid-row: 1; }
  .header-tools { grid-column: 2; grid-row: 1; justify-self: end; }
  .primary-nav { grid-column: 1 / -1; grid-row: 2; justify-content: space-between; }
  .left-rail, .right-rail { top: 84px; height: calc(100vh - 84px); }
  .breadcrumbs { top: 84px; }
}
@media (max-width: 1120px) {
  .page-shell, .page-shell.no-outline { grid-template-columns: 250px minmax(0, 1fr); }
  .right-rail { display: none; }
  .primary-nav { gap: 9px; }
  .primary-nav a { font-size: 12px; }
}
@media (max-width: 900px) {
  .hero { grid-template-columns: minmax(0, 1fr); }
  .hero-logo { width: min(100%, 220px); justify-self: center; }
}
@media (max-width: 820px) {
  .site-header { gap: 10px; }
  .nav-toggle { display: inline-block; }
  .brand { font-size: 14px; }
  .primary-nav { display: none; }
  .header-tools { margin-left: auto; }
  .search-box { width: min(38vw, 220px); }
  .page-shell, .page-shell.no-outline { display: block; }
  .left-rail { position: fixed; z-index: 30; top: 64px; bottom: 0; left: 0; width: min(86vw, 320px); height: auto; transform: translateX(-105%); transition: transform .18s ease; box-shadow: 10px 0 40px #0004; }
  .nav-open .left-rail { transform: translateX(0); }
}
@media (max-width: 520px) {
  .site-header { display: grid; grid-template-columns: auto minmax(0, 1fr) auto; gap: 8px; min-height: 96px; padding: 8px 10px; }
  .nav-toggle { grid-column: 1; grid-row: 1; }
  .brand { grid-column: 2; grid-row: 1; min-width: 0; gap: 6px; font-size: 12px; line-height: 1.2; }
  .brand span { overflow-wrap: anywhere; }
  .brand-mark { flex-basis: 28px; width: 28px; height: 28px; }
  .brand-mark img { top: -8px; left: -15px; width: 58px; height: 58px; }
  .header-tools { display: contents; }
  .header-tools .search-box { grid-column: 1 / -1; grid-row: 2; width: 100%; }
  .header-tools .theme-toggle { grid-column: 3; grid-row: 1; }
  .theme-toggle, .nav-toggle { min-height: 36px; padding: 5px 8px; font-size: 12px; }
  .search-input { min-height: 36px; padding-left: 7px; font-size: 12px; }
  .search-shortcut { display: none; }
  .left-rail { top: 96px; }
  .breadcrumbs { top: 96px; }
  body.nav-open::after { top: 96px; }
  .main-content { padding: 21px 17px 55px; }
  .lesson-footer { flex-direction: column; }
  .hero { padding: 23px 18px; }
}
@media (max-width: 360px) {
  .brand { font-size: 11px; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; }
}