/*
 * AI-SKILLS site styles.
 * A calm, spacious system: soft rounded surfaces, generous whitespace, the
 * Inter sans for prose (a clean, highly legible reading face, consistent on
 * every OS) and the Play display face for the brand and headings. Two themes,
 * one accent. Depth comes from light shadow and border, never from noise.
 */

:root {
  --bg: #12100e;
  /* Theme the browser's native controls (scrollbars, the category select's
     dropdown popup and its scrollbar) to the dark scheme. */
  color-scheme: dark;
  --surface: #1a1815;
  --surface-2: #221f1b;
  --border: #322e29;
  --border-hover: #4a443c;
  --text-1: #efe9df;
  --text-2: #c8c0b3;
  --text-3: #a49b8c;
  --text-4: #857c6e;
  --accent: #d8a24a;
  --accent-soft: rgba(216, 162, 74, 0.14);
  --accent-strong: #e6b45f;
  /* Primary-button surface and the text that sits on it. Dark theme's accent
     is light gold, so dark text reads well on it. */
  --accent-btn: #d8a24a;
  --accent-btn-hover: #e6b45f;
  --on-accent: #171310;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.28);
  --shadow-md: 0 6px 24px rgba(0, 0, 0, 0.30);
  --radius: 16px;
  --radius-sm: 11px;
  --radius-pill: 999px;
  --maxw: 1120px;
}

:root[data-theme="light"] {
  --bg: #f4f1ea;
  color-scheme: light;
  --surface: #ffffff;
  --surface-2: #faf7f0;
  --border: #e3ddd0;
  --border-hover: #cfc7b5;
  --text-1: #221f1a;
  --text-2: #4a453c;
  --text-3: #6b6558;
  --text-4: #8c8474;
  --accent: #b07216;
  --accent-soft: rgba(176, 114, 22, 0.10);
  --accent-strong: #965f0c;
  /* Light theme's accent is a dark brown; white text on a slightly deeper
     brown clears WCAG AA where the old near-black text was unreadable. */
  --accent-btn: #965f0c;
  --accent-btn-hover: #7d4d08;
  --on-accent: #ffffff;
  --shadow-sm: 0 1px 2px rgba(60, 50, 30, 0.06);
  --shadow-md: 0 10px 30px rgba(60, 50, 30, 0.10);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

/* Themed scrollbars, seamless in both light and dark. Firefox/standard uses
   scrollbar-color; WebKit uses the pseudo-elements. The thumb rides a
   transparent track with a bg-colored border so it reads as inset. */
* { scrollbar-color: var(--border-hover) transparent; scrollbar-width: thin; }
::-webkit-scrollbar { width: 12px; height: 12px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background-color: var(--border-hover);
  border-radius: var(--radius-pill);
  border: 3px solid var(--bg);
  background-clip: padding-box;
}
::-webkit-scrollbar-thumb:hover { background-color: var(--accent); }
::-webkit-scrollbar-corner { background: transparent; }
body {
  background: var(--bg);
  color: var(--text-2);
  font-family: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
.mono { font-family: ui-monospace, "Cascadia Code", "SF Mono", Consolas, monospace; }
.play { font-family: "Play", ui-monospace, Consolas, monospace; }
a { color: var(--accent); text-decoration-color: color-mix(in srgb, var(--accent) 45%, transparent); text-underline-offset: 3px; }
a:hover { color: var(--accent-strong); }
.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 28px; }
::selection { background: var(--accent-soft); }

/* Header */
header.site {
  position: sticky; top: 0; z-index: 20;
  padding: 15px 0;
  background: color-mix(in srgb, var(--bg) 86%, transparent);
  backdrop-filter: saturate(140%) blur(10px);
  border-bottom: 1px solid var(--border);
}
header.site .wrap { display: flex; align-items: center; justify-content: space-between; gap: 18px; }
.brand {
  display: flex; align-items: center; gap: 11px;
  font-family: "Play", ui-monospace, Consolas, monospace;
  font-weight: 700; font-size: 19px; letter-spacing: -0.3px;
  color: var(--text-1); text-decoration: none;
}
.brand span { color: var(--accent); }
.brand svg { flex-shrink: 0; border-radius: 7px; }
nav.top { display: flex; gap: 22px; align-items: center; font-family: "Play", ui-monospace, Consolas, monospace; font-size: 14px; }
nav.top a { color: var(--text-3); text-decoration: none; }
nav.top a:hover { color: var(--text-1); }

/* Theme toggle: a knob that glides between sun and moon */
.theme-toggle {
  position: relative; width: 50px; height: 27px; padding: 0; flex-shrink: 0;
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: var(--radius-pill); cursor: pointer;
  transition: border-color .2s, background-color .25s;
}
.theme-toggle:hover { border-color: var(--accent); }
.theme-toggle:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.tt-knob {
  position: absolute; top: 2px; left: 2px; width: 21px; height: 21px;
  border-radius: 50%; background: var(--accent); color: var(--bg);
  display: flex; align-items: center; justify-content: center;
  transition: transform .3s cubic-bezier(.4, 0, .2, 1), background-color .25s;
}
:root[data-theme="light"] .tt-knob { transform: translateX(23px); }
.tt-knob svg { width: 12px; height: 12px; }
.tt-knob .tt-sun { display: none; }
:root[data-theme="light"] .tt-knob .tt-sun { display: block; }
:root[data-theme="light"] .tt-knob .tt-moon { display: none; }

/* Buttons */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 13px 24px; border-radius: var(--radius-sm);
  font-family: "Play", ui-monospace, Consolas, monospace; font-size: 15px;
  text-decoration: none; border: 1px solid var(--border); color: var(--text-2);
  background: var(--surface); cursor: pointer;
  transition: border-color .18s, color .18s, transform .18s, box-shadow .18s, background-color .18s;
}
.btn:hover { border-color: var(--accent); color: var(--text-1); transform: translateY(-1px); box-shadow: var(--shadow-sm); }
.btn.primary {
  background: var(--accent-btn); border-color: var(--accent-btn); color: var(--on-accent);
  font-weight: 700; box-shadow: var(--shadow-sm);
}
.btn.primary:hover { background: var(--accent-btn-hover); border-color: var(--accent-btn-hover); color: var(--on-accent); }
.btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* Footer */
footer.site { border-top: 1px solid var(--border); padding: 30px 0 48px; margin-top: 24px; }
footer.site .wrap { font-family: "Play", ui-monospace, Consolas, monospace; font-size: 13px; color: var(--text-4); }
footer.site a { color: var(--text-3); }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; }
}

/* Tablet and below: tighten the shell without losing anything. */
@media (max-width: 820px) {
  .wrap { padding: 0 24px; }
  nav.top { gap: 18px; font-size: 13px; }
  .btn { padding: 12px 20px; }
}

/* Phones: the header wraps to two centered rows so every link stays
   reachable, and tap targets stay comfortable. No hamburger needed for a
   three-link nav. */
@media (max-width: 560px) {
  .wrap { padding: 0 18px; }
  body { font-size: 16px; }
  header.site { padding: 12px 0; }
  header.site .wrap { flex-wrap: wrap; justify-content: center; gap: 12px 18px; }
  .brand { font-size: 18px; }
  nav.top { gap: 16px; width: 100%; justify-content: center; }
  nav.top a { padding: 4px 2px; }
}