/* =========================================================================
   Sol Advisor — Guide  |  Design System
   Zero-build static site. Dark-tech theme with light toggle.
   ========================================================================= */

:root {
  /* Brand ramp */
  --c-brand-1: #7c5cff;   /* purple */
  --c-brand-2: #2f8bff;   /* blue   */
  --c-brand-3: #19c39c;   /* teal   */

  /* Dark theme (default) */
  --bg: #0a0c12;
  --bg-soft: #0f131c;
  --surface: #141a26;
  --surface-2: #1b2230;
  --border: rgba(255, 255, 255, 0.08);
  --border-strong: rgba(255, 255, 255, 0.16);
  --text: #e8ecf4;
  --text-soft: #aab3c5;
  --text-dim: #6f7a90;
  --accent: var(--c-brand-1);
  --accent-2: var(--c-brand-2);
  --code-bg: #0c1018;
  --shadow: 0 10px 40px rgba(0, 0, 0, 0.45);

  --radius: 14px;
  --radius-sm: 10px;
  --maxw: 1080px;
  --nav-h: 64px;
  --font: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  --mono: "JetBrains Mono", "SFMono-Regular", Menlo, Consolas, "Liberation Mono", monospace;
}

html[data-theme="light"] {
  --bg: #ffffff;
  --bg-soft: #f6f8fc;
  --surface: #ffffff;
  --surface-2: #eef2f9;
  --border: rgba(15, 23, 42, 0.10);
  --border-strong: rgba(15, 23, 42, 0.18);
  --text: #0e1422;
  --text-soft: #3f4a5e;
  --text-dim: #6b7689;
  --code-bg: #f3f5fa;
  --shadow: 0 10px 40px rgba(20, 30, 60, 0.10);
}

* { 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;
  transition: background-color .25s ease, color .25s ease;
}

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

img { max-width: 100%; height: auto; }

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

/* ---------- Nav ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  height: var(--nav-h);
  display: flex; align-items: center;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: saturate(150%) blur(12px);
  border-bottom: 1px solid var(--border);
}
.nav .container { display: flex; align-items: center; justify-content: space-between; width: 100%; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 600; color: var(--text); font-size: 16px; }
.brand:hover { text-decoration: none; }
.brand .logo {
  width: 30px; height: 30px; border-radius: 8px;
  background: linear-gradient(135deg, var(--c-brand-1), var(--c-brand-2));
  display: grid; place-items: center; color: #fff; font-weight: 700; font-size: 15px;
}
.nav-links { display: flex; align-items: center; gap: 6px; }
.nav-links a {
  color: var(--text-soft); padding: 8px 12px; border-radius: 8px; font-size: 14.5px;
}
.nav-links a:hover { color: var(--text); background: var(--surface); text-decoration: none; }
.nav-actions { display: flex; align-items: center; gap: 8px; }
.icon-btn {
  width: 38px; height: 38px; display: grid; place-items: center;
  border: 1px solid var(--border); background: var(--surface); color: var(--text);
  border-radius: 9px; cursor: pointer; font-size: 16px;
}
.icon-btn:hover { border-color: var(--border-strong); }
.menu-toggle { display: none; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 11px 18px; border-radius: 10px; font-weight: 600; font-size: 14.5px;
  cursor: pointer; border: 1px solid transparent; transition: transform .12s ease, opacity .2s;
}
.btn:hover { text-decoration: none; transform: translateY(-1px); }
.btn-primary { background: linear-gradient(135deg, var(--c-brand-1), var(--c-brand-2)); color: #fff; }
.btn-ghost { background: var(--surface); color: var(--text); border-color: var(--border); }
.btn-ghost:hover { border-color: var(--border-strong); }

/* ---------- Hero ---------- */
.hero { padding: 84px 0 56px; position: relative; overflow: hidden; }
.hero::before {
  content: ""; position: absolute; inset: -30% -10% auto -10%; height: 460px;
  background: radial-gradient(60% 70% at 50% 0%, rgba(124, 92, 255, 0.18), transparent 70%),
              radial-gradient(40% 60% at 80% 10%, rgba(47, 139, 255, 0.14), transparent 70%);
  pointer-events: none;
}
.badge {
  display: inline-flex; align-items: center; gap: 7px;
  font-size: 12.5px; color: var(--text-soft);
  background: var(--surface); border: 1px solid var(--border);
  padding: 5px 11px; border-radius: 999px; margin-bottom: 18px;
}
.badge .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--c-brand-3); }
.hero h1 {
  font-size: clamp(30px, 5.4vw, 52px); line-height: 1.08; margin: 0 0 18px; letter-spacing: -0.02em;
  font-weight: 700;
}
.hero h1 .grad {
  background: linear-gradient(120deg, var(--c-brand-1), var(--c-brand-2) 55%, var(--c-brand-3));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero p.lead { font-size: clamp(16px, 2.2vw, 19px); color: var(--text-soft); max-width: 680px; margin: 0 0 26px; }
.hero-cta { display: flex; gap: 12px; flex-wrap: wrap; }
.hero-meta { margin-top: 22px; color: var(--text-dim); font-size: 13.5px; }
.hero-meta a { color: var(--text-soft); }

/* ---------- Sections ---------- */
.section { padding: 56px 0; }
.section.tight { padding: 36px 0; }
.section-head { margin-bottom: 30px; }
.section-head h2 { font-size: clamp(24px, 3.4vw, 32px); margin: 0 0 8px; letter-spacing: -0.01em; }
.section-head p { color: var(--text-soft); margin: 0; max-width: 680px; }
.eyebrow { color: var(--accent); font-weight: 600; font-size: 13px; letter-spacing: .04em; text-transform: uppercase; }

/* ---------- Cards ---------- */
.grid { display: grid; gap: 18px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 22px; transition: border-color .2s, transform .15s;
}
.card:hover { border-color: var(--border-strong); transform: translateY(-2px); }
.card .ico {
  width: 42px; height: 42px; border-radius: 11px; display: grid; place-items: center;
  background: linear-gradient(135deg, rgba(124,92,255,.18), rgba(47,139,255,.18));
  color: var(--accent); font-size: 20px; margin-bottom: 14px;
}
.card h3 { margin: 0 0 8px; font-size: 17.5px; }
.card p { margin: 0; color: var(--text-soft); font-size: 14.5px; }

/* ---------- Mode comparison ---------- */
.modes { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.mode {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 24px; position: relative; overflow: hidden;
}
.mode.featured { border-color: color-mix(in srgb, var(--accent) 45%, var(--border)); }
.mode h3 { margin: 0 0 4px; font-size: 19px; display: flex; align-items: center; gap: 9px; }
.tag { font-size: 11.5px; padding: 3px 8px; border-radius: 999px; background: var(--surface-2); color: var(--text-soft); border: 1px solid var(--border); }
.mode .who { color: var(--text-dim); font-size: 13px; margin: 2px 0 14px; }
.mode ul { margin: 0; padding-left: 18px; color: var(--text-soft); font-size: 14.5px; }
.mode ul li { margin: 6px 0; }

/* ---------- Code block ---------- */
.code {
  position: relative; background: var(--code-bg); border: 1px solid var(--border);
  border-radius: var(--radius-sm); padding: 16px 18px; overflow-x: auto;
  font-family: var(--mono); font-size: 13.5px; color: var(--text); line-height: 1.7;
}
.code code { font-family: inherit; white-space: pre; }
.copy-btn {
  position: absolute; top: 10px; right: 10px;
  background: var(--surface-2); border: 1px solid var(--border); color: var(--text-soft);
  border-radius: 7px; padding: 4px 9px; font-size: 12px; cursor: pointer;
}
.copy-btn:hover { color: var(--text); border-color: var(--border-strong); }
.code .c { color: var(--text-dim); }
.code .p { color: var(--c-brand-3); }

/* ---------- Steps ---------- */
.steps { counter-reset: step; display: grid; gap: 14px; }
.step {
  display: grid; grid-template-columns: 38px 1fr; gap: 16px; align-items: start;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px 20px;
}
.step .n {
  width: 38px; height: 38px; border-radius: 50%; display: grid; place-items: center;
  background: linear-gradient(135deg, var(--c-brand-1), var(--c-brand-2)); color: #fff; font-weight: 700;
}
.step h4 { margin: 4px 0 6px; font-size: 16px; }
.step p { margin: 0; color: var(--text-soft); font-size: 14.5px; }

/* ---------- FAQ ---------- */
.faq details {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-sm);
  padding: 4px 18px; margin-bottom: 10px;
}
.faq summary {
  cursor: pointer; padding: 14px 0; font-weight: 600; font-size: 15.5px; list-style: none;
  display: flex; justify-content: space-between; align-items: center; gap: 12px;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; color: var(--text-dim); font-size: 20px; }
.faq details[open] summary::after { content: "\2212"; }
.faq .answer { padding: 0 0 16px; color: var(--text-soft); font-size: 14.5px; }
.faq .answer code { font-family: var(--mono); background: var(--code-bg); padding: 1px 6px; border-radius: 5px; font-size: 13px; }

/* ---------- Callout / disclaimer ---------- */
.note {
  border: 1px solid var(--border); border-left: 3px solid var(--c-brand-3);
  background: var(--surface); border-radius: var(--radius-sm); padding: 14px 18px;
  color: var(--text-soft); font-size: 14px;
}
.note strong { color: var(--text); }

/* ---------- Diagram ---------- */
.diagram { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px; }
.diagram svg { width: 100%; height: auto; }

/* ---------- Table ---------- */
.table { width: 100%; border-collapse: collapse; font-size: 14.5px; }
.table th, .table td { text-align: left; padding: 12px 14px; border-bottom: 1px solid var(--border); }
.table th { color: var(--text-soft); font-weight: 600; }
.table tr:last-child td { border-bottom: none; }

/* ---------- Footer ---------- */
.footer { border-top: 1px solid var(--border); background: var(--bg-soft); padding: 40px 0 28px; margin-top: 40px; }
.footer .cols { display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 28px; }
.footer h4 { font-size: 14px; margin: 0 0 12px; color: var(--text); }
.footer a { color: var(--text-soft); display: block; padding: 4px 0; font-size: 14px; }
.footer a:hover { color: var(--text); }
.footer .disclaim { color: var(--text-dim); font-size: 13px; margin-top: 8px; max-width: 360px; }
.footer .bottom { margin-top: 28px; padding-top: 18px; border-top: 1px solid var(--border); color: var(--text-dim); font-size: 13px; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 10px; }

/* ---------- 404 ---------- */
.err { text-align: center; padding: 90px 0; }
.err .code404 { font-size: 96px; font-weight: 800; background: linear-gradient(135deg, var(--c-brand-1), var(--c-brand-2)); -webkit-background-clip: text; background-clip: text; color: transparent; }

/* ---------- Responsive ---------- */
@media (max-width: 860px) {
  .grid-3 { grid-template-columns: 1fr; }
  .grid-2, .modes { grid-template-columns: 1fr; }
  .footer .cols { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 680px) {
  .nav-links {
    position: absolute; top: var(--nav-h); left: 0; right: 0;
    flex-direction: column; align-items: stretch; gap: 2px; padding: 12px 16px;
    background: var(--bg); border-bottom: 1px solid var(--border);
    display: none;
  }
  .nav-links.open { display: flex; }
  .menu-toggle { display: grid; }
  .footer .cols { grid-template-columns: 1fr; }
}