/* ============================================================
   GPN — GPU-Native Network · stylesheet
   No build step, no external CDNs. Dark-first, light-friendly.
   ============================================================ */

:root {
  --bg: #07090f;
  --bg-2: #0b0f17;
  --panel: #0f1521;
  --card: #121a28;
  --line: #23303f;
  --line-soft: #1a2430;
  --text: #e9eef5;
  --muted: #9aa7b8;
  --muted-2: #6f7d8f;
  --accent: #7c6cff;
  --accent-2: #22d3ee;
  --green: #3fb950;
  --amber: #f0a63a;
  --red: #f0616d;
  --grad: linear-gradient(92deg, #7c6cff 0%, #22d3ee 100%);
  --shadow: 0 12px 34px rgba(0, 0, 0, .45);
  --radius: 14px;
  --radius-sm: 9px;
  --maxw: 1120px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
}

/* Light theme (opt-in via the toggle) */
html.light {
  --bg: #f7f9fc;
  --bg-2: #eef2f8;
  --panel: #ffffff;
  --card: #ffffff;
  --line: #d7dfea;
  --line-soft: #e6ecf4;
  --text: #101827;
  --muted: #4a5768;
  --muted-2: #6b7788;
  --shadow: 0 10px 28px rgba(16, 24, 39, .10);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--accent-2); text-decoration: none; }
a:hover { text-decoration: underline; }

h1, h2, h3, h4 { line-height: 1.18; font-weight: 800; letter-spacing: -0.01em; }
h2 { font-size: clamp(1.5rem, 1.1rem + 1.6vw, 2.15rem); margin: 6px 0 12px; }
h3 { font-size: 1.15rem; margin: 0 0 8px; }
p { margin: 0 0 14px; }

code, kbd, pre { font-family: var(--mono); }
code {
  background: rgba(124, 108, 255, .12);
  border: 1px solid var(--line-soft);
  padding: .12em .42em;
  border-radius: 6px;
  font-size: .88em;
  word-break: break-word;
}
pre {
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 16px 18px;
  overflow-x: auto;
  font-size: .86rem;
  line-height: 1.55;
  margin: 0 0 16px;
}
pre code { background: none; border: 0; padding: 0; font-size: inherit; }

img, svg { max-width: 100%; }

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 22px; }

.skip-link {
  position: absolute; left: -999px; top: 0; z-index: 100;
  background: var(--accent); color: #07090f; padding: 10px 16px; border-radius: 0 0 8px 0;
}
.skip-link:focus { left: 0; }

/* ---------- Header / nav ---------- */
.site-header {
  position: sticky; top: 0; z-index: 60;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.nav {
  display: flex; align-items: center; justify-content: space-between;
  min-height: 62px; gap: 12px;
}
.brand {
  display: flex; align-items: center; gap: 10px;
  font-weight: 800; letter-spacing: .02em; color: var(--text); font-size: 1.05rem;
}
.brand:hover { text-decoration: none; }
.brand .dot {
  width: 26px; height: 26px; border-radius: 8px; background: var(--grad);
  display: inline-flex; align-items: center; justify-content: center;
  color: #07090f; font-size: 14px; font-weight: 900;
}
.brand small { color: var(--muted-2); font-weight: 600; font-size: .72rem; letter-spacing: .06em; }

.nav-links { display: flex; align-items: center; gap: 4px; flex-wrap: wrap; }
.nav-links a {
  color: var(--muted); font-size: .9rem; padding: 8px 11px; border-radius: 8px;
}
.nav-links a:hover { color: var(--text); background: var(--panel); text-decoration: none; }
.nav-links a[aria-current="page"] { color: var(--text); background: var(--panel); box-shadow: inset 0 -2px 0 var(--accent); }

.nav-actions { display: flex; align-items: center; gap: 8px; }
.nav-toggle {
  display: none; background: var(--panel); border: 1px solid var(--line); color: var(--text);
  border-radius: 8px; padding: 9px 12px; font-size: 1rem; cursor: pointer;
}
.theme-toggle {
  background: var(--panel); border: 1px solid var(--line); color: var(--text);
  border-radius: 8px; padding: 8px 11px; cursor: pointer; font-size: .95rem; line-height: 1;
}
.theme-toggle:hover { border-color: var(--accent); }

@media (max-width: 860px) {
  .nav-toggle { display: inline-block; }
  .nav-links {
    display: none; position: absolute; left: 0; right: 0; top: 62px;
    flex-direction: column; align-items: stretch; gap: 2px;
    background: var(--bg-2); border-bottom: 1px solid var(--line); padding: 10px 16px 16px;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 12px; }
}

/* ---------- Hero ---------- */
.hero { padding: clamp(48px, 7vw, 96px) 0 clamp(36px, 5vw, 64px); position: relative; overflow: hidden; }
.hero::after {
  content: ""; position: absolute; inset: -40% 40% auto -10%; height: 520px;
  background: radial-gradient(closest-side, rgba(124,108,255,.20), transparent 70%);
  pointer-events: none;
}
.hero .inner { position: relative; }
.badge {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 6px 14px; border: 1px solid var(--line); border-radius: 999px;
  font-size: .8rem; color: var(--muted); margin-bottom: 20px; background: var(--panel);
}
.badge .live-dot { width: 8px; height: 8px; border-radius: 50%; background: var(--green); box-shadow: 0 0 0 4px rgba(63,185,80,.18); }
.hero h1 { font-size: clamp(2.05rem, 1.2rem + 4.2vw, 3.6rem); margin: 0 0 18px; }
.hero h1 .grad { background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero .lede { max-width: 720px; font-size: clamp(1.02rem, .95rem + .4vw, 1.22rem); color: var(--muted); margin-bottom: 28px; }
.hero-cta { display: flex; gap: 12px; flex-wrap: wrap; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 22px; border-radius: 10px; font-weight: 700; font-size: .95rem;
  background: var(--grad); color: #07090f; border: 1px solid transparent; cursor: pointer;
}
.btn:hover { text-decoration: none; filter: brightness(1.06); }
.btn.ghost { background: transparent; border-color: var(--line); color: var(--text); }
.btn.ghost:hover { border-color: var(--accent); filter: none; }
.btn.small { padding: 9px 15px; font-size: .86rem; }
.btn:disabled { opacity: .55; cursor: not-allowed; filter: none; }

/* ---------- Sections ---------- */
section { padding: clamp(40px, 5vw, 68px) 0; border-top: 1px solid var(--line-soft); }
section.first { border-top: 0; }
.kicker { color: var(--accent-2); font-size: .78rem; letter-spacing: .14em; text-transform: uppercase; font-weight: 700; }
.sub { color: var(--muted); max-width: 760px; margin: 0 0 30px; font-size: 1.02rem; }

/* ---------- Grids ---------- */
.grid { display: grid; gap: 18px; }
.grid.cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid.cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid.cols-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 900px) { .grid.cols-3, .grid.cols-4 { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 620px) { .grid.cols-2, .grid.cols-3, .grid.cols-4 { grid-template-columns: 1fr; } }

.card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 22px; box-shadow: var(--shadow);
}
.card h3 { display: flex; align-items: center; gap: 10px; }
.card p:last-child { margin-bottom: 0; }
.card .ico {
  width: 34px; height: 34px; border-radius: 9px; flex: none;
  display: inline-flex; align-items: center; justify-content: center;
  background: rgba(124,108,255,.14); color: var(--accent); font-size: 17px;
}
.card.plain { box-shadow: none; background: var(--panel); }

/* ---------- Problem / answer rows ---------- */
.split { display: grid; grid-template-columns: 1fr auto 1fr; gap: 16px; align-items: stretch; }
@media (max-width: 760px) { .split { grid-template-columns: 1fr; } }
.compare {
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px;
}
.compare.bad { border-left: 3px solid var(--red); }
.compare.good { border-left: 3px solid var(--green); }
.compare h4 { margin: 0 0 6px; font-size: .95rem; }
.arrow { display: flex; align-items: center; justify-content: center; font-size: 1.6rem; color: var(--muted-2); }
@media (max-width: 760px) { .arrow { display: none; } }

/* ---------- Mode diagram ---------- */
.modes { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-top: 8px; }
@media (max-width: 860px) { .modes { grid-template-columns: 1fr; } }
.mode {
  position: relative; background: var(--card); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 24px 22px; text-align: center;
}
.mode .m-title { font-weight: 800; font-size: 1.08rem; margin-bottom: 4px; }
.mode .m-earn { color: var(--muted); font-size: .86rem; min-height: 40px; }
.mode .m-tag {
  display: inline-block; margin-top: 8px; font-size: .72rem; letter-spacing: .06em; text-transform: uppercase;
  color: var(--accent-2); border: 1px solid var(--line); border-radius: 999px; padding: 3px 10px;
}
.mode.active { border-color: var(--accent); box-shadow: 0 0 0 1px rgba(124,108,255,.35), var(--shadow); }
.mode .ring {
  width: 54px; height: 54px; margin: 0 auto 12px; border-radius: 14px;
  display: flex; align-items: center; justify-content: center; font-size: 24px;
  background: rgba(34,211,238,.10); color: var(--accent-2); border: 1px solid var(--line);
}
.switch-note {
  margin-top: 18px; text-align: center; color: var(--muted); font-size: .9rem;
}
.switch-note b { color: var(--text); }

/* ---------- Steps ---------- */
.steps { counter-reset: step; display: grid; gap: 14px; }
.step {
  position: relative; padding: 18px 20px 18px 62px;
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
}
.step::before {
  counter-increment: step; content: counter(step);
  position: absolute; left: 18px; top: 50%; transform: translateY(-50%);
  width: 30px; height: 30px; border-radius: 50%; display: flex; align-items: center; justify-content: center;
  background: var(--grad); color: #07090f; font-weight: 800; font-size: .9rem;
}
.step h4 { margin: 0 0 4px; font-size: 1rem; }
.step p { margin: 0; color: var(--muted); font-size: .92rem; }

/* ---------- Table ---------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius); }
table { border-collapse: collapse; width: 100%; font-size: .9rem; min-width: 560px; }
th, td { text-align: left; padding: 12px 15px; border-bottom: 1px solid var(--line-soft); vertical-align: top; }
thead th { background: var(--panel); font-size: .78rem; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); }
tbody tr:last-child td { border-bottom: 0; }
tbody tr:hover { background: rgba(124,108,255,.05); }
td code { font-size: .84em; }

/* ---------- Status chips ---------- */
.chip {
  display: inline-flex; align-items: center; gap: 6px; font-size: .76rem; font-weight: 700;
  padding: 4px 10px; border-radius: 999px; border: 1px solid var(--line); white-space: nowrap;
}
.chip .d { width: 7px; height: 7px; border-radius: 50%; }
.chip.up { color: var(--green); border-color: rgba(63,185,80,.35); background: rgba(63,185,80,.08); }
.chip.up .d { background: var(--green); }
.chip.warn { color: var(--amber); border-color: rgba(240,166,58,.35); background: rgba(240,166,58,.08); }
.chip.warn .d { background: var(--amber); }
.chip.down { color: var(--red); border-color: rgba(240,97,109,.35); background: rgba(240,97,109,.08); }
.chip.down .d { background: var(--red); }
.chip.neutral { color: var(--muted); }
.chip.neutral .d { background: var(--muted-2); }

/* ---------- Callouts ---------- */
.callout {
  border: 1px solid var(--line); border-left: 4px solid var(--accent);
  background: var(--panel); border-radius: var(--radius-sm); padding: 16px 18px; margin: 0 0 18px;
}
.callout.warn { border-left-color: var(--amber); }
.callout.danger { border-left-color: var(--red); }
.callout p:last-child { margin-bottom: 0; }
.callout .ct { font-weight: 800; display: block; margin-bottom: 4px; }

/* ---------- Feature list ---------- */
ul.checks { list-style: none; padding: 0; margin: 0; display: grid; gap: 10px; }
ul.checks li { position: relative; padding-left: 28px; color: var(--muted); }
ul.checks li::before {
  content: "✓"; position: absolute; left: 0; top: 0; color: var(--green); font-weight: 800;
}
ul.checks li b { color: var(--text); }

/* ---------- Stat row ---------- */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
@media (max-width: 760px) { .stats { grid-template-columns: repeat(2, 1fr); } }
.stat { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px; }
.stat .v { font-size: 1.5rem; font-weight: 800; }
.stat .l { color: var(--muted); font-size: .82rem; }

/* ---------- Forms ---------- */
label { display: block; font-size: .85rem; font-weight: 700; margin-bottom: 6px; }
.hint { color: var(--muted-2); font-size: .8rem; font-weight: 400; }
input[type="text"], input[type="url"], textarea, select {
  width: 100%; background: var(--bg-2); color: var(--text);
  border: 1px solid var(--line); border-radius: 9px; padding: 11px 13px;
  font-family: inherit; font-size: .93rem;
}
input:focus, textarea:focus, select:focus { outline: 2px solid var(--accent); outline-offset: 1px; border-color: var(--accent); }
textarea { resize: vertical; min-height: 96px; font-family: var(--font); }
.field { margin-bottom: 14px; }
.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
@media (max-width: 620px) { .field-row { grid-template-columns: 1fr; } }

/* ---------- Try-it result ---------- */
.result {
  margin-top: 16px; border: 1px solid var(--line); border-radius: var(--radius-sm);
  background: var(--bg-2); padding: 16px; min-height: 76px; font-size: .92rem;
  white-space: pre-wrap; word-break: break-word;
}
.result.empty { color: var(--muted-2); }
.result .ok { color: var(--green); font-weight: 700; }
.result .err { color: var(--red); font-weight: 700; }
.result .meter { color: var(--muted); font-size: .8rem; margin-top: 8px; display: block; }
.spinner {
  display: inline-block; width: 15px; height: 15px; border-radius: 50%;
  border: 2px solid var(--line); border-top-color: var(--accent); animation: spin .8s linear infinite;
  vertical-align: -2px;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ---------- Footer ---------- */
.site-footer { border-top: 1px solid var(--line); padding: 40px 0 30px; color: var(--muted); font-size: .88rem; }
.foot-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 24px; }
@media (max-width: 760px) { .foot-grid { grid-template-columns: 1fr 1fr; } }
.foot-grid h4 { font-size: .8rem; text-transform: uppercase; letter-spacing: .08em; color: var(--muted-2); margin-bottom: 10px; }
.foot-grid a { display: block; color: var(--muted); padding: 3px 0; }
.foot-grid a:hover { color: var(--text); }
.foot-bottom { margin-top: 28px; padding-top: 18px; border-top: 1px solid var(--line-soft); display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.foot-bottom p { margin: 0; }

/* ---------- Utilities ---------- */
.muted { color: var(--muted); }
.center { text-align: center; }
.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }
.page-head { padding: clamp(36px, 5vw, 60px) 0 8px; }
.page-head h1 { font-size: clamp(1.8rem, 1.2rem + 2.4vw, 2.6rem); margin: 6px 0 12px; }
.page-head p { color: var(--muted); max-width: 760px; font-size: 1.05rem; }
.small { font-size: .84rem; }
.nowrap { white-space: nowrap; }

/* ---------- Print ---------- */
@media print {
  .site-header, .site-footer, .nav-actions, .hero-cta, .no-print { display: none !important; }
  body { background: #fff; color: #000; }
  a { color: #000; text-decoration: underline; }
  section { border: 0; padding: 12px 0; }
  .card, .callout, pre, .table-wrap { box-shadow: none; break-inside: avoid; }
}