/* Digital Defenders: learning site styles */
:root {
  --bg: #061024;
  --bg-2: #0a1a36;
  --panel: #0e2245;
  --panel-2: #12295a;
  --line: #1f3d6e;
  --line-soft: #173058;
  --text: #e8eefb;
  --muted: #9fb2d3;
  --faint: #6f84a8;
  --cyan: #4fc3f7;
  --cyan-soft: rgba(79, 195, 247, 0.14);
  --coral: #ff6b4f;
  --coral-soft: rgba(255, 107, 79, 0.16);
  --amber: #ffc857;
  --amber-soft: rgba(255, 200, 87, 0.16);
  --green: #4fd1a5;
  --green-soft: rgba(79, 209, 165, 0.14);
  --slate: #7f8ea9;
  --radius: 14px;
  --sans: "Space Grotesk", "Segoe UI", system-ui, -apple-system, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background-color: var(--bg);
  background-image:
    radial-gradient(ellipse 80% 50% at 50% -10%, rgba(30, 90, 190, 0.35), transparent 70%),
    linear-gradient(rgba(79, 195, 247, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(79, 195, 247, 0.035) 1px, transparent 1px);
  background-size: 100% 100%, 48px 48px, 48px 48px;
  background-attachment: fixed;
  color: var(--text);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
}
a { color: var(--cyan); text-underline-offset: 3px; }
a:hover { color: #8fdcff; }
:focus-visible { outline: 2px solid var(--cyan); outline-offset: 3px; border-radius: 4px; }
img { max-width: 100%; height: auto; }

.skip { position: absolute; left: -999px; top: 8px; background: var(--cyan); color: #04122a; padding: 8px 12px; border-radius: 8px; z-index: 10; }
.skip:focus { left: 12px; }

.wrap { width: 100%; max-width: 1080px; margin: 0 auto; padding: 0 16px; }
.read { max-width: 760px; }

/* Header */
.site-head { border-bottom: 1px solid var(--line-soft); background: rgba(6, 16, 36, 0.82); position: sticky; top: 0; z-index: 5; backdrop-filter: blur(8px); }
.site-head .wrap { display: flex; align-items: center; justify-content: space-between; gap: 12px; min-height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--text); font-weight: 700; letter-spacing: -0.01em; }
.brand img { width: 38px; height: 38px; border-radius: 8px; }
.brand span { font-size: 18px; }
.nav { display: flex; gap: 4px; flex-wrap: wrap; }
.nav a { color: var(--muted); text-decoration: none; font-size: 15px; padding: 6px 10px; border-radius: 8px; }
.nav a:hover { color: var(--text); background: var(--panel); }

/* Hero */
.hero { padding: 64px 0 40px; }
.kicker { font-family: var(--mono); color: var(--cyan); font-size: 14px; letter-spacing: 0.22em; text-transform: uppercase; margin: 0 0 14px; }
.hero h1 { font-size: clamp(34px, 6vw, 56px); line-height: 1.08; margin: 0 0 16px; letter-spacing: -0.02em; }
.hero h1 em { font-style: normal; color: var(--cyan); }
.hero p.lede { color: var(--muted); font-size: 19px; max-width: 640px; margin: 0 0 26px; }
.cta { display: flex; gap: 12px; flex-wrap: wrap; }
.btn { display: inline-flex; align-items: center; gap: 8px; padding: 11px 18px; border-radius: 10px; font-weight: 600; text-decoration: none; font-size: 16px; border: 1px solid var(--line); color: var(--text); background: var(--panel); }
.btn:hover { border-color: var(--cyan); color: var(--text); }
.btn.primary { background: var(--cyan); color: #04122a; border-color: var(--cyan); }
.btn.primary:hover { background: #8fdcff; color: #04122a; }
.btn svg { width: 18px; height: 18px; fill: currentColor; }

/* Topic grid */
.group { padding: 18px 0 30px; }
.group-head { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; border-bottom: 1px solid var(--line-soft); padding-bottom: 10px; margin-bottom: 18px; }
.group-head h2 { font-size: 22px; margin: 0; }
.group-head p { margin: 0; color: var(--faint); font-size: 14px; font-family: var(--mono); }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 300px), 1fr)); gap: 14px; }
.card { display: block; text-decoration: none; color: var(--text); background: linear-gradient(180deg, var(--panel), var(--bg-2)); border: 1px solid var(--line-soft); border-radius: var(--radius); padding: 18px 18px 16px; transition: border-color .15s, transform .15s; }
.card:hover { border-color: var(--cyan); transform: translateY(-2px); color: var(--text); }
.card .num { font-family: var(--mono); font-size: 13px; color: var(--cyan); letter-spacing: 0.1em; }
.card h3 { font-size: 19px; margin: 6px 0 6px; line-height: 1.3; }
.card p { margin: 0; color: var(--muted); font-size: 15px; line-height: 1.5; }
.card .tag { display: inline-block; margin-top: 12px; font-family: var(--mono); font-size: 12px; padding: 2px 8px; border-radius: 999px; border: 1px solid var(--line); color: var(--faint); }
.card .tag.hot { color: var(--coral); border-color: rgba(255, 107, 79, 0.45); }

/* Article */
.crumbs { font-family: var(--mono); font-size: 13px; color: var(--faint); padding-top: 26px; }
.crumbs a { color: var(--faint); text-decoration: none; }
.crumbs a:hover { color: var(--cyan); }
.article-head { padding: 18px 0 8px; }
.article-head h1 { font-size: clamp(30px, 5vw, 44px); line-height: 1.12; letter-spacing: -0.02em; margin: 6px 0 12px; }
.dek { color: var(--muted); font-size: 19px; margin: 0; }

.glance { display: flex; flex-wrap: wrap; gap: 8px; margin: 18px 0 4px; padding: 0; list-style: none; }
.glance li { font-family: var(--mono); font-size: 13px; padding: 5px 10px; border-radius: 8px; background: var(--panel); border: 1px solid var(--line-soft); color: var(--muted); }
.glance li b { color: var(--text); font-weight: 600; }
.glance li.hot { border-color: rgba(255, 107, 79, 0.5); }
.glance li.hot b { color: var(--coral); }

figure.diagram { margin: 26px 0 26px; background: linear-gradient(180deg, var(--bg-2), var(--bg)); border: 1px solid var(--line-soft); border-radius: var(--radius); padding: 16px; }
.diagram .scroll { overflow-x: auto; -webkit-overflow-scrolling: touch; }
.diagram svg { display: block; width: 100%; height: auto; }
.diagram .desk svg { min-width: 620px; }
.diagram .m { display: none; max-width: 420px; margin: 0 auto; }
.diagram figcaption { color: var(--faint); font-size: 14px; margin-top: 10px; font-family: var(--mono); }
@media (max-width: 680px) {
  .diagram .desk { display: none; }
  .diagram .m { display: block; }
  figure.diagram { padding: 10px; }
}

.body p { margin: 0 0 18px; }
.body strong { color: #ffffff; }
.body code { font-family: var(--mono); font-size: 0.88em; background: var(--panel); border: 1px solid var(--line-soft); padding: 1px 6px; border-radius: 6px; color: #cfe9ff; overflow-wrap: anywhere; }
.body ol.five { padding-left: 0; list-style: none; counter-reset: five; margin: 0 0 22px; }
.body ol.five li { counter-increment: five; position: relative; padding: 12px 14px 12px 52px; margin-bottom: 8px; background: var(--panel); border: 1px solid var(--line-soft); border-radius: 10px; }
.body ol.five li::before { content: counter(five); position: absolute; left: 14px; top: 12px; width: 26px; height: 26px; border-radius: 50%; background: var(--coral-soft); color: var(--coral); font-family: var(--mono); font-weight: 700; font-size: 14px; display: grid; place-items: center; }
.body ol.five li span { display: block; color: var(--muted); font-size: 15px; }

.examples { margin: 28px 0; }
.examples h2, .sources summary, .next-prev h2 { font-size: 15px; font-family: var(--mono); letter-spacing: 0.14em; text-transform: uppercase; color: var(--cyan); margin: 0 0 12px; font-weight: 500; }
.ex { display: block; text-decoration: none; background: var(--panel); border: 1px solid var(--line-soft); border-left: 3px solid var(--coral); border-radius: 10px; padding: 14px 16px; margin-bottom: 10px; color: var(--text); }
.ex:hover { border-color: var(--cyan); border-left-color: var(--coral); color: var(--text); }
.ex b { display: block; font-size: 16px; }
.ex span { display: block; color: var(--muted); font-size: 15px; line-height: 1.5; margin-top: 2px; }
.ex small { display: block; color: var(--faint); font-family: var(--mono); font-size: 12px; margin-top: 6px; overflow-wrap: anywhere; }

.sources { margin: 22px 0; border-top: 1px solid var(--line-soft); padding-top: 16px; }
.sources summary { cursor: pointer; margin: 0; }
.sources ul { margin: 12px 0 0; padding-left: 18px; color: var(--muted); font-size: 14px; }
.sources li { margin-bottom: 4px; overflow-wrap: anywhere; }
.checked { font-family: var(--mono); font-size: 13px; color: var(--faint); margin-top: 10px; }

.next-prev { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin: 30px 0 10px; }
.next-prev a { display: block; text-decoration: none; padding: 14px 16px; border-radius: 10px; border: 1px solid var(--line-soft); background: var(--panel); color: var(--text); }
.next-prev a:hover { border-color: var(--cyan); color: var(--text); }
.next-prev small { display: block; font-family: var(--mono); color: var(--faint); font-size: 12px; }
.next-prev .nx { text-align: right; }
@media (max-width: 560px) { .next-prev { grid-template-columns: 1fr; } .next-prev .nx { text-align: left; } }

.watch { margin: 34px 0 10px; padding: 20px; border-radius: var(--radius); border: 1px solid var(--line); background: radial-gradient(ellipse at top left, rgba(79,195,247,.16), transparent 60%), var(--panel); display: flex; gap: 16px; align-items: center; justify-content: space-between; flex-wrap: wrap; }
.watch p { margin: 0; color: var(--muted); }
.watch p b { color: var(--text); display: block; font-size: 18px; }

/* Footer */
.site-foot { margin-top: 56px; border-top: 1px solid var(--line-soft); padding: 28px 0 40px; color: var(--faint); font-size: 14px; }
.site-foot .wrap { display: flex; justify-content: space-between; gap: 18px; flex-wrap: wrap; }
.site-foot a { color: var(--muted); text-decoration: none; margin-right: 14px; }
.site-foot a:hover { color: var(--cyan); }
.site-foot .mono { font-family: var(--mono); }

/* ---------- SVG diagram vocabulary ---------- */
.diagram svg text { font-family: var(--sans); fill: var(--text); font-size: 17px; }
.diagram svg .tm { fill: var(--muted); font-size: 14px; }
.diagram svg .tf { fill: var(--faint); font-size: 13px; }
.diagram svg .tb { font-weight: 700; }
.diagram svg .ts { font-size: 15px; }
.diagram svg .tl { font-size: 20px; font-weight: 700; }
.diagram svg .mono { font-family: var(--mono); font-size: 14px; }
.diagram svg .big { font-size: 26px; }
.diagram svg .tc { fill: var(--cyan); }
.diagram svg .tr { fill: var(--coral); }
.diagram svg .ta { fill: var(--amber); }
.diagram svg .tg { fill: var(--green); }
.diagram svg .tdark { fill: #04122a; }
.diagram svg .box { fill: var(--panel); stroke: var(--line); stroke-width: 1.5; }
.diagram svg .box2 { fill: var(--panel-2); stroke: var(--line); stroke-width: 1.5; }
.diagram svg .boxc { fill: var(--cyan-soft); stroke: var(--cyan); stroke-width: 1.5; }
.diagram svg .boxr { fill: var(--coral-soft); stroke: var(--coral); stroke-width: 1.8; }
.diagram svg .boxa { fill: var(--amber-soft); stroke: var(--amber); stroke-width: 1.5; }
.diagram svg .boxg { fill: var(--green-soft); stroke: var(--green); stroke-width: 1.5; }
.diagram svg .solidc { fill: var(--cyan); }
.diagram svg .solidr { fill: var(--coral); }
.diagram svg .ln { stroke: var(--slate); stroke-width: 1.8; fill: none; }
.diagram svg .lnc { stroke: var(--cyan); stroke-width: 2; fill: none; }
.diagram svg .lnr { stroke: var(--coral); stroke-width: 2.4; fill: none; }
.diagram svg .lng { stroke: var(--green); stroke-width: 2; fill: none; }
.diagram svg .dash { stroke-dasharray: 7 6; }
.diagram svg .dot { stroke-dasharray: 2 5; stroke-linecap: round; }
.diagram svg .ahs { fill: var(--slate); }
.diagram svg .ahc { fill: var(--cyan); }
.diagram svg .ahr { fill: var(--coral); }
.diagram svg .ahg { fill: var(--green); }
.diagram svg .heat1 { fill: rgba(79, 209, 165, 0.30); stroke: var(--bg); stroke-width: 2; }
.diagram svg .heat2 { fill: rgba(255, 200, 87, 0.32); stroke: var(--bg); stroke-width: 2; }
.diagram svg .heat3 { fill: rgba(255, 140, 80, 0.45); stroke: var(--bg); stroke-width: 2; }
.diagram svg .heat4 { fill: rgba(255, 80, 70, 0.62); stroke: var(--bg); stroke-width: 2; }

@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }
@media print {
  body { background: #fff; color: #000; }
  .site-head, .site-foot, .watch, .next-prev { display: none; }
}

@media (max-width: 520px) {
  .brand span { font-size: 16px; white-space: nowrap; }
  .brand img { width: 32px; height: 32px; }
  .nav { flex-wrap: nowrap; }
  .nav a { padding: 6px 7px; font-size: 14px; }
  .nav a:first-child { display: none; }
  .hero { padding-top: 40px; }
}

/* Episodes */
.episode { margin: 28px 0; }
.episode h2 { font-size: 15px; font-family: var(--mono); letter-spacing: 0.14em; text-transform: uppercase; color: var(--cyan); margin: 0 0 12px; font-weight: 500; }
.video { position: relative; aspect-ratio: 16 / 9; border-radius: var(--radius); overflow: hidden; border: 1px solid var(--line); background: #000; }
.video iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.vcard { padding: 0 0 16px; overflow: hidden; }
.vcard .thumb { display: block; position: relative; aspect-ratio: 16 / 9; overflow: hidden; background: var(--bg-2); margin-bottom: 12px; }
.vcard .thumb img { width: 100%; height: 100%; object-fit: cover; display: block; }
.vcard .play { position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%); width: 58px; height: 40px; border-radius: 10px; background: rgba(6,16,36,.82); border: 1px solid var(--cyan); color: var(--cyan); display: grid; place-items: center; font-size: 18px; }
.vcard:hover .play { background: var(--cyan); color: #04122a; }
.vcard .num, .vcard h3 { padding: 0 18px; display: block; }
.card .vtag { margin-left: 6px; color: var(--cyan); border-color: rgba(79,195,247,.45); }
.grid.vids { grid-template-columns: repeat(auto-fill, minmax(min(100%, 340px), 1fr)); }