/* EEG for Beginners: course site styles. Dark by default, in the alexni.ai palette. */

:root {
  --bg: #05070d;
  --bg-soft: #080b14;
  --surface: rgba(255, 255, 255, .035);
  --surface-solid: #0c1019;
  --surface-2: rgba(255, 255, 255, .06);
  --ink: #ffffff;
  --ink-2: #cbd5e1;
  --muted: #94a3b8;
  --line: rgba(255, 255, 255, .09);
  --line-strong: rgba(255, 255, 255, .16);
  --accent: #22d3ee;
  --accent-ink: #67e8f9;
  --accent-contrast: #05070d;
  --violet-glow: #8b5cf6;
  --green: #4ade80;
  --blue: #60a5fa;
  --violet: #a78bfa;
  --amber: #fbbf24;
  --red: #f87171;
  --note: #22d3ee;
  --tip: #4ade80;
  --important: #a78bfa;
  --warning: #fbbf24;
  --caution: #f87171;
  --code-bg: rgba(0, 0, 0, .35);
  --figure-bg: #ffffff;
  --shadow: 0 1px 0 rgba(255, 255, 255, .04) inset, 0 10px 30px rgba(0, 0, 0, .35);
  --glow: 0 0 0 1px rgba(34, 211, 238, .35), 0 0 28px rgba(34, 211, 238, .18);
  --radius: 14px;
  --sidebar: 272px;
  --rail: 220px;
  --measure: 760px;
  --font: "Inter", ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --display: "Inter", ui-sans-serif, system-ui, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --wave-opacity: 1;
  color-scheme: dark;
}

:root[data-theme="light"] {
  --bg: #f8fafc;
  --bg-soft: #ffffff;
  --surface: rgba(255, 255, 255, .78);
  --surface-solid: #ffffff;
  --surface-2: rgba(15, 23, 42, .045);
  --ink: #0f172a;
  --ink-2: #334155;
  --muted: #475569;
  --line: rgba(15, 23, 42, .1);
  --line-strong: rgba(15, 23, 42, .18);
  --accent: #0e7490;
  --accent-ink: #0e7490;
  --accent-contrast: #ffffff;
  --violet-glow: #7c3aed;
  --green: #15803d;
  --blue: #1d4ed8;
  --violet: #6d28d9;
  --amber: #b45309;
  --red: #b91c1c;
  --note: #0e7490;
  --tip: #15803d;
  --important: #6d28d9;
  --warning: #b45309;
  --caution: #b91c1c;
  --code-bg: rgba(15, 23, 42, .04);
  --shadow: 0 1px 2px rgba(15, 23, 42, .05), 0 8px 24px rgba(15, 23, 42, .06);
  --glow: 0 0 0 1px rgba(14, 116, 144, .35), 0 0 24px rgba(14, 116, 144, .12);
  --wave-opacity: .55;
  color-scheme: light;
}

* { box-sizing: border-box; }
html {
  scroll-padding-top: 76px; -webkit-text-size-adjust: 100%;
  background:
    radial-gradient(60% 50% at 50% -10%, color-mix(in srgb, var(--accent) 12%, transparent), transparent 60%),
    radial-gradient(40% 40% at 92% 6%, color-mix(in srgb, var(--violet-glow) 12%, transparent), transparent 60%),
    var(--bg);
  background-attachment: fixed;
}
body {
  margin: 0;
  min-height: 100vh;
  background: transparent;
  color: var(--ink-2);
  font: 16px/1.7 var(--font);
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent-ink); text-decoration-thickness: 1px; text-underline-offset: 3px; text-decoration-color: color-mix(in srgb, var(--accent) 45%, transparent); }
a:hover { color: var(--accent); text-decoration-color: var(--accent); }
img { max-width: 100%; height: auto; }
::selection { background: color-mix(in srgb, var(--accent) 35%, transparent); color: var(--ink); }
.skip { position: absolute; left: -999px; top: 0; }
.skip:focus { left: 12px; top: 12px; z-index: 100; background: var(--surface-solid); padding: 8px 12px; border-radius: 6px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* ---------- animated background ---------- */
.bg-waves {
  position: fixed; inset: 0; z-index: -1; pointer-events: none; overflow: hidden;
  opacity: var(--wave-opacity);
  -webkit-mask-image: radial-gradient(85% 70% at 50% 0%, #000, transparent 80%);
  mask-image: radial-gradient(85% 70% at 50% 0%, #000, transparent 80%);
}
.bg-waves svg { position: absolute; top: 0; left: 0; width: 200%; height: 620px; color: var(--accent); }
.bg-waves path { fill: none; stroke: currentColor; stroke-width: 1.1; stroke-linecap: round; vector-effect: non-scaling-stroke; }
.bg-waves .drift { animation: drift linear infinite; }
.bg-blob { position: absolute; top: -140px; left: 50%; width: 44rem; height: 18rem; transform: translateX(-50%); border-radius: 50%; background: color-mix(in srgb, var(--accent) 14%, transparent); filter: blur(110px); }
.bg-blob.violet { left: 88%; top: -60px; width: 26rem; background: color-mix(in srgb, var(--violet-glow) 12%, transparent); }
@keyframes drift { from { transform: translateX(0); } to { transform: translateX(-50%); } }
@media (prefers-reduced-motion: reduce) { .bg-waves .drift { animation: none; } }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 30;
  display: flex; align-items: center; gap: 12px;
  height: 60px; padding: 0 18px;
  background: color-mix(in srgb, var(--bg) 72%, transparent);
  backdrop-filter: blur(14px) saturate(140%);
  -webkit-backdrop-filter: blur(14px) saturate(140%);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none; font-weight: 700; font-size: 1.02rem; letter-spacing: -.01em; white-space: nowrap; }
.brand:hover { color: var(--ink); }
.brand-mark { width: 36px; height: 18px; color: var(--accent); filter: drop-shadow(0 0 6px color-mix(in srgb, var(--accent) 60%, transparent)); }
.brand small { font: 500 .7rem var(--mono); color: var(--accent); letter-spacing: .04em; }
.menu-btn, .theme-btn {
  display: inline-grid; place-items: center; width: 38px; height: 38px;
  border: 1px solid var(--line-strong); border-radius: 10px; background: var(--surface); color: var(--ink); cursor: pointer;
}
.menu-btn { display: none; }
.theme-btn { margin-left: auto; }
.theme-btn:hover, .menu-btn:hover { box-shadow: var(--glow); }
.gh-btn { display: inline-flex; align-items: center; gap: 8px; height: 38px; padding: 0 16px; border-radius: 99px; border: 1px solid var(--line-strong); color: var(--ink); text-decoration: none; font-weight: 600; font-size: .88rem; }
.gh-btn:hover { color: var(--ink); box-shadow: var(--glow); }
.search { position: relative; flex: 0 1 340px; margin-left: 24px; }
.search input {
  width: 100%; height: 38px; padding: 0 12px 0 34px; font: inherit; font-size: .9rem;
  color: var(--ink); background: var(--surface) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='2' stroke-linecap='round'%3E%3Ccircle cx='11' cy='11' r='7'/%3E%3Cpath d='m20 20-3.5-3.5'/%3E%3C/svg%3E") no-repeat 11px center;
  border: 1px solid var(--line-strong); border-radius: 10px;
}
.search input::placeholder { color: var(--muted); }
.search input:focus { outline: none; box-shadow: var(--glow); border-color: transparent; }
.search-results {
  position: absolute; top: 46px; left: 0; right: 0; max-height: 60vh; overflow: auto;
  margin: 0; padding: 6px; list-style: none; background: var(--surface-solid);
  border: 1px solid var(--line-strong); border-radius: var(--radius); box-shadow: var(--shadow);
}
.search-results a { display: block; padding: 8px 10px; border-radius: 8px; color: var(--ink); text-decoration: none; }
.search-results a:hover, .search-results a.on { background: var(--surface-2); }
.search-results small { display: block; color: var(--muted); font-size: .8rem; line-height: 1.4; }

/* ---------- shell ---------- */
.shell { display: grid; grid-template-columns: var(--sidebar) minmax(0, 1fr) var(--rail); }
.sidebar {
  position: sticky; top: 60px; height: calc(100vh - 60px); overflow-y: auto;
  padding: 20px 14px 40px; border-right: 1px solid var(--line); font-size: .9rem;
  scrollbar-width: thin; scrollbar-color: var(--line-strong) transparent;
}
.sidebar ul { list-style: none; margin: 0 0 14px; padding: 0; }
.nav-group { margin: 16px 10px 6px; font: 500 .68rem var(--mono); letter-spacing: .16em; text-transform: uppercase; color: var(--accent); opacity: .85; }
.sidebar a { display: flex; gap: 10px; align-items: baseline; padding: 6px 10px; border-radius: 8px; color: var(--muted); text-decoration: none; line-height: 1.35; }
.sidebar a:hover { background: var(--surface-2); color: var(--ink); }
.sidebar a.active { background: var(--surface-2); color: var(--ink); font-weight: 600; box-shadow: inset 2px 0 0 var(--accent); }
.nav-num { font-family: var(--mono); font-size: .74rem; color: var(--muted); min-width: 1.6em; opacity: .8; }
.sidebar a.active .nav-num { color: var(--accent); opacity: 1; }

.content { min-width: 0; padding: 40px 48px 80px; }
.content > * { max-width: var(--measure); margin-left: auto; margin-right: auto; }
body.wide .content > *, body.home .content > * { max-width: 1120px; }
body.wide .shell, body.home .shell { grid-template-columns: var(--sidebar) minmax(0, 1fr); }
body.wide .rail, body.home .rail { display: none; }
body.home .prose > :not(.cards):not(.section-title):not(.eyebrow) { max-width: var(--measure); }
.rail { padding: 40px 16px; }
.toc { position: sticky; top: 84px; font-size: .84rem; }
.toc p { margin: 0 0 10px; font: 500 .68rem var(--mono); letter-spacing: .16em; text-transform: uppercase; color: var(--accent); }
.toc ul { list-style: none; margin: 0; padding: 0; border-left: 1px solid var(--line); }
.toc li a { display: block; padding: 4px 0 4px 12px; margin-left: -1px; color: var(--muted); text-decoration: none; border-left: 1px solid transparent; line-height: 1.35; }
.toc li.toc-h3 a { padding-left: 24px; font-size: .8rem; }
.toc li a:hover { color: var(--ink); }
.toc li a.on { color: var(--accent-ink); border-left-color: var(--accent); }

/* ---------- page header ---------- */
.page-head { margin-bottom: 30px; padding-bottom: 24px; border-bottom: 1px solid var(--line); }
.page-head h1 { margin: 14px 0 10px; font-family: var(--display); font-weight: 750; font-size: clamp(2rem, 4.2vw, 2.9rem); line-height: 1.08; letter-spacing: -.025em; color: var(--ink); }
.lede { margin: 0; font-size: 1.12rem; color: var(--muted); }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chip { font: 500 .72rem var(--mono); padding: 4px 10px; border-radius: 99px; background: var(--surface); color: var(--muted); border: 1px solid var(--line-strong); }
.chip:first-child { color: var(--accent); border-color: color-mix(in srgb, var(--accent) 40%, transparent); }
.chip-time { color: var(--green); }

/* ---------- home hero ---------- */
.hero { padding: 28px 0 8px; }
.pill { display: inline-flex; align-items: center; gap: 8px; padding: 5px 13px; border-radius: 99px; border: 1px solid color-mix(in srgb, var(--accent) 35%, var(--line)); background: color-mix(in srgb, var(--accent) 6%, transparent); font: 500 .76rem var(--mono); color: var(--accent-ink); }
.pill::before { content: ""; width: 7px; height: 7px; border-radius: 50%; background: var(--accent); box-shadow: 0 0 10px var(--accent); animation: pulse 2.4s ease-in-out infinite; }
@keyframes pulse { 50% { opacity: .35; } }
.hero h1 { margin: 22px 0 18px; font-family: var(--display); font-weight: 780; font-size: clamp(2.6rem, 6.4vw, 4.6rem); line-height: 1.02; letter-spacing: -.035em; color: var(--ink); }
.hero h1 span { display: block; color: var(--accent); text-shadow: 0 0 40px color-mix(in srgb, var(--accent) 35%, transparent); }
.hero .lede { max-width: 640px; font-size: 1.18rem; line-height: 1.65; }
.hero .lede strong { color: var(--ink); font-weight: 600; }
.cta { display: flex; flex-wrap: wrap; gap: 12px; margin: 28px 0 0; }
.btn-primary, .btn-ghost { display: inline-flex; align-items: center; gap: 8px; height: 44px; padding: 0 20px; border-radius: 99px; font-weight: 600; font-size: .95rem; text-decoration: none; transition: box-shadow .15s ease, transform .15s ease; }
.btn-primary { background: var(--accent); color: var(--accent-contrast); }
.btn-primary:hover { color: var(--accent-contrast); box-shadow: 0 0 30px color-mix(in srgb, var(--accent) 55%, transparent); transform: translateY(-1px); }
.btn-ghost { border: 1px solid var(--line-strong); color: var(--ink); background: var(--surface); }
.btn-ghost:hover { color: var(--ink); box-shadow: var(--glow); }
.stats { display: grid; grid-template-columns: repeat(4, 1fr); margin: 44px 0 52px; border: 1px solid var(--line-strong); border-radius: var(--radius); background: var(--surface); backdrop-filter: blur(6px); }
.stat { padding: 18px 20px; border-left: 1px solid var(--line); }
.stat:first-child { border-left: 0; }
.stat b { display: block; font: 600 1.25rem var(--mono); color: var(--accent); }
.stat span { font-size: .88rem; color: var(--muted); }
.eyebrow { display: block; margin: 0 0 10px; font: 500 .72rem var(--mono); letter-spacing: .2em; text-transform: uppercase; color: var(--accent); }
.section-title { margin: 0 0 18px; font-family: var(--display); font-weight: 750; font-size: clamp(1.6rem, 3vw, 2.2rem); letter-spacing: -.025em; line-height: 1.15; color: var(--ink); }

/* ---------- prose ---------- */
.prose { color: var(--ink-2); }
.prose h2 { margin: 2.4em 0 .6em; font-family: var(--display); font-weight: 720; font-size: 1.62rem; line-height: 1.22; letter-spacing: -.02em; color: var(--ink); }
.prose h3 { margin: 1.8em 0 .5em; font-size: 1.15rem; font-weight: 650; color: var(--ink); }
.prose h4 { margin: 1.4em 0 .4em; font-size: 1rem; color: var(--ink); }
.prose h2:first-child { margin-top: 0; }
.prose .header-anchor { margin-left: .35em; color: var(--accent); text-decoration: none; opacity: 0; font-weight: 400; }
.prose h2:hover .header-anchor, .prose h3:hover .header-anchor { opacity: .7; }
.prose p, .prose ul, .prose ol { margin: 0 0 1.1em; }
.prose li { margin: .3em 0; }
.prose li::marker { color: var(--accent); }
.prose li > ul, .prose li > ol { margin: .25em 0; }
.prose li:has(> input[type=checkbox]) { list-style: none; margin-left: -1.3em; }
.prose input[type=checkbox] { accent-color: var(--accent); }
.prose hr { border: 0; border-top: 1px solid var(--line); margin: 2.5em 0; }
.prose strong { font-weight: 650; color: var(--ink); }
.prose img { display: block; margin: 1.6em auto .5em; border-radius: 12px; border: 1px solid var(--line-strong); background: var(--figure-bg); padding: 6px; box-shadow: var(--shadow); }
.prose p:has(> img) + p > em:only-child, .prose p > img + em { display: block; font-size: .86rem; color: var(--muted); text-align: center; }
.prose p > a:only-child > img { margin: 1em 0; max-width: 480px; padding: 0; transition: box-shadow .15s ease; }
.prose p > a:only-child:hover > img { box-shadow: var(--glow); }
.prose blockquote { margin: 1.4em 0; padding: .2em 1.1em; border-left: 2px solid var(--accent); color: var(--muted); }
.prose :not(pre) > code { font-family: var(--mono); font-size: .85em; padding: .12em .38em; border-radius: 6px; background: var(--surface-2); color: var(--accent-ink); border: 1px solid var(--line); }

@media (min-width: 1300px) {
  .prose p:has(> img:only-child) { margin-left: -60px; margin-right: -60px; }
}

/* ---------- callouts ---------- */
.callout { --c: var(--note); margin: 1.6em 0; padding: 14px 18px 4px; border-radius: var(--radius); background: color-mix(in srgb, var(--c) 7%, transparent); border: 1px solid color-mix(in srgb, var(--c) 28%, transparent); }
.callout-title { margin: 0 0 .4em !important; font: 600 .7rem var(--mono); letter-spacing: .16em; text-transform: uppercase; color: var(--c); }
.callout-tip { --c: var(--tip); }
.callout-important { --c: var(--important); }
.callout-warning { --c: var(--warning); }
.callout-caution { --c: var(--caution); }

/* ---------- details / self-check ---------- */
.prose details { margin: .7em 0; border: 1px solid var(--line-strong); border-radius: var(--radius); background: var(--surface); transition: box-shadow .15s ease; }
.prose details:hover { box-shadow: var(--glow); }
.prose summary { cursor: pointer; padding: 12px 16px 12px 44px; font-weight: 550; color: var(--ink); list-style: none; position: relative; }
.prose summary::-webkit-details-marker { display: none; }
.prose summary::before { content: "?"; position: absolute; left: 13px; top: 12px; width: 21px; height: 21px; border-radius: 50%; display: grid; place-items: center; font: 600 .74rem var(--mono); border: 1px solid color-mix(in srgb, var(--accent) 50%, transparent); color: var(--accent); }
.prose details[open] summary::before { content: "✓"; color: var(--green); border-color: color-mix(in srgb, var(--green) 50%, transparent); }
.prose details > :not(summary) { padding: 0 16px; }
.prose details[open] { padding-bottom: .4em; }

/* ---------- tables ---------- */
.table-wrap { overflow-x: auto; margin: 1.4em 0; border: 1px solid var(--line-strong); border-radius: var(--radius); background: var(--surface); }
.prose table { width: 100%; border-collapse: collapse; font-size: .9rem; line-height: 1.5; }
.prose th { text-align: left; font: 600 .74rem var(--mono); letter-spacing: .06em; text-transform: uppercase; color: var(--accent); background: var(--surface-2); }
.prose th, .prose td { padding: 10px 13px; border-bottom: 1px solid var(--line); vertical-align: top; }
.prose tr:last-child td { border-bottom: 0; }
.prose tbody tr:hover td { background: color-mix(in srgb, var(--accent) 4%, transparent); }

/* ---------- code ---------- */
.code { margin: 1.3em 0; border: 1px solid var(--line-strong); border-radius: var(--radius); overflow: hidden; background: var(--code-bg); }
.code-bar { display: flex; justify-content: space-between; align-items: center; padding: 6px 10px 6px 14px; font: 500 .72rem var(--mono); color: var(--accent); border-bottom: 1px solid var(--line); text-transform: lowercase; background: var(--surface-2); }
.copy { font: inherit; padding: 3px 10px; border-radius: 99px; border: 1px solid var(--line-strong); background: transparent; color: var(--muted); cursor: pointer; }
.copy:hover { color: var(--ink); box-shadow: var(--glow); }
.copy.done { color: var(--green); }
.code pre { margin: 0; padding: 14px 16px; overflow-x: auto; font: .84rem/1.65 var(--mono); background: transparent !important; color: var(--ink-2); }
pre.mermaid { font-family: var(--font); font-size: 15px; margin: 1.6em 0; padding: 18px; text-align: center; background: var(--surface); border: 1px solid var(--line-strong); border-radius: var(--radius); overflow-x: auto; }

/* ---------- cards ---------- */
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 14px; margin: 0 0 3em; }
.card { position: relative; display: flex; flex-direction: column; gap: 6px; padding: 18px 18px 16px; border: 1px solid var(--line-strong); border-radius: var(--radius); background: var(--surface); color: var(--ink); text-decoration: none; backdrop-filter: blur(6px); transition: transform .15s ease, box-shadow .15s ease, border-color .15s ease; overflow: hidden; }
.card::after { content: ""; position: absolute; inset: auto -40% -60% auto; width: 160px; height: 160px; border-radius: 50%; background: color-mix(in srgb, var(--accent) 18%, transparent); filter: blur(40px); opacity: 0; transition: opacity .2s ease; }
.card:hover { transform: translateY(-2px); box-shadow: var(--glow); border-color: transparent; color: var(--ink); }
.card:hover::after { opacity: 1; }
.card-num { font: 600 .82rem var(--mono); color: var(--accent); }
.card-week { position: absolute; top: 18px; right: 18px; font: 500 .68rem var(--mono); color: var(--muted); letter-spacing: .06em; }
.card strong { font-weight: 680; font-size: 1.04rem; line-height: 1.3; letter-spacing: -.01em; }
.card-sum { font-size: .86rem; color: var(--muted); line-height: 1.5; }
.card-time { margin-top: auto; padding-top: 8px; font: 500 .72rem var(--mono); color: var(--green); }
.card.feature { border-color: color-mix(in srgb, var(--accent) 40%, var(--line)); background: linear-gradient(140deg, color-mix(in srgb, var(--accent) 10%, transparent), var(--surface) 60%); }

/* ---------- pager ---------- */
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 56px; }
.pager a { display: flex; flex-direction: column; padding: 14px 18px; border: 1px solid var(--line-strong); border-radius: var(--radius); background: var(--surface); text-decoration: none; color: var(--ink); transition: box-shadow .15s ease; }
.pager a:hover { box-shadow: var(--glow); color: var(--ink); }
.pager .next { text-align: right; grid-column: 2; }
.pager small { font: 500 .68rem var(--mono); letter-spacing: .14em; text-transform: uppercase; color: var(--accent); }

.site-foot { margin-top: 64px; padding-top: 22px; border-top: 1px solid var(--line); font-size: .84rem; color: var(--muted); display: flex; flex-wrap: wrap; gap: 8px 18px; justify-content: space-between; }

/* ---------- responsive ---------- */
@media (max-width: 1200px) {
  .shell { grid-template-columns: var(--sidebar) minmax(0, 1fr); }
  .rail { display: none; }
}
@media (max-width: 900px) {
  .shell, body.wide .shell, body.home .shell { grid-template-columns: minmax(0, 1fr); }
  .menu-btn { display: inline-grid; }
  .sidebar { position: fixed; top: 60px; left: 0; z-index: 25; width: min(320px, 86vw); background: var(--bg-soft); transform: translateX(-102%); transition: transform .18s ease; box-shadow: var(--shadow); }
  body.nav-open .sidebar { transform: none; }
  .content { padding: 24px 16px 64px; }
  .search { margin-left: 0; flex: 1 1 auto; }
  .brand span, .gh-btn { display: none; }
  .pager { grid-template-columns: 1fr; }
  .pager .next { grid-column: 1; }
  .stats { grid-template-columns: 1fr 1fr; }
  .stat:nth-child(3) { border-left: 0; }
  .stat:nth-child(n+3) { border-top: 1px solid var(--line); }
}
@media print {
  .topbar, .sidebar, .rail, .pager, .copy, .bg-waves { display: none !important; }
  :root { --bg: #fff; --ink: #000; --ink-2: #111; --muted: #444; }
  body { background: #fff; }
  .shell { display: block; }
  .content { padding: 0; }
  .prose details { border: 0; }
}