/* === Neo-minimal theme by GPT-5 Pro (keeps your vibe, just cooler) === */
/* Core tokens */
:root {
  --bg: #0f1115;
  --panel: #121622;
  --text: #e6e8ef;
  --muted: #98a2b3;
  --accent: #7dd3fc;
  --accent-ink: #082f49;
  --border: color-mix(in oklab, white 8%, transparent);
  --ring: color-mix(in oklab, var(--accent) 50%, transparent);
  --shadow-1: 0 0 0 1px var(--border);
  --shadow-2: 0 8px 24px rgba(0,0,0,.35);
  --radius: 14px;
}
@media (prefers-color-scheme: light) {
  :root {
    --bg: #f8fafc;
    --panel: #ffffff;
    --text: #0b1220;
    --muted: #475569;
    --accent: #0ea5e9;
    --accent-ink: #e6f7ff;
    --border: color-mix(in oklab, black 8%, transparent);
    --ring: color-mix(in oklab, var(--accent) 35%, transparent);
    --shadow-2: 0 8px 26px rgba(2,6,23,.08);
  }
}
/* Manual theme override */
html[data-theme="light"] { color-scheme: light; }
html[data-theme="dark"]  { color-scheme: dark;  }

/* Base reset */
*, *::before, *::after { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, "Noto Sans JP", "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
  line-height: 1.65;
  background: radial-gradient(1200px 800px at 20% -10%, color-mix(in oklab, var(--accent) 15%, transparent), transparent),
              radial-gradient(800px 600px at 120% 10%, color-mix(in oklab, var(--accent) 10%, transparent), transparent),
              var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* Typography */
h1, h2, h3 { line-height: 1.25; }
h1 { font-size: clamp(28px, 4.6vw, 42px); margin: 0 0 .6rem; }
h2 { font-size: clamp(18px, 2.4vw, 24px); margin: 1.2rem 0 .4rem; }
p  { margin: 0 0 1rem; color: var(--text); }
small, .muted { color: var(--muted); }

/* Layout */
.container { width: min(1080px, 92vw); margin: 0 auto; padding: 24px; }
.site-header {
  position: sticky; top: 0; z-index: 20;
  backdrop-filter: saturate(160%) blur(10px);
  background: color-mix(in oklab, var(--bg) 70%, transparent);
  border-bottom: 1px solid var(--border);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.brand {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 10px; border-radius: 12px; font-weight: 800; letter-spacing: .3px;
  color: var(--text); text-decoration: none;
}
.brand::before {
  content: ""; width: 10px; height: 10px; border-radius: 50%;
  background: radial-gradient(circle at 30% 30%, var(--accent), transparent 60%);
  box-shadow: 0 0 0 3px color-mix(in oklab, var(--accent) 35%, transparent);
}

/* Nav */
.nav { display: flex; align-items: center; gap: 6px; flex-wrap: wrap; }
.nav-link {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 12px; border-radius: 10px; color: var(--muted); text-decoration: none;
  position: relative;
}
.nav-link:hover { color: var(--text); }
.nav-link[aria-current="page"] {
  color: var(--text); background: color-mix(in oklab, var(--panel) 92%, transparent);
  border: 1px solid var(--border);
}
.nav-link::after {
  content:""; position:absolute; inset:auto 8px 6px; height:2px; border-radius:2px;
  background: color-mix(in oklab, var(--accent) 70%, transparent);
  transform: scaleX(0); transform-origin: left; transition: transform .25s ease;
}
.nav-link:hover::after { transform: scaleX(1); }

/* Hero */
.hero { padding: 48px 0 20px; }
.hero-title { font-weight: 800; letter-spacing: .2px; }
.hero-desc { color: var(--muted); max-width: 65ch; }
.hero-cta { display: flex; gap: 12px; flex-wrap: wrap; }

/* Buttons */
.btn {
  --bg: var(--accent);
  --ink: var(--accent-ink);
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 10px 16px; border-radius: var(--radius);
  border: 1px solid color-mix(in oklab, var(--bg) 60%, var(--border));
  color: var(--ink); background: linear-gradient(180deg, color-mix(in oklab, var(--bg) 86%, transparent), var(--bg));
  font-weight: 700; text-decoration: none; box-shadow: var(--shadow-2);
  transition: translate .15s ease, filter .15s ease, box-shadow .2s ease;
  will-change: transform, filter;
}
.btn:hover { filter: brightness(1.03); translate: 0 -1px; box-shadow: 0 10px 30px color-mix(in oklab, var(--bg) 30%, transparent); }
.btn:active { translate: 0 0; }
.btn.ghost {
  background: color-mix(in oklab, var(--panel) 92%, transparent);
  color: var(--text);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-1);
}

/* Icon-only button (theme toggle) */
.icon-btn {
  display: inline-grid; place-items: center;
  width: 38px; height: 38px; border-radius: 10px; border: 1px solid var(--border);
  background: color-mix(in oklab, var(--panel) 92%, transparent);
  color: var(--text); cursor: pointer;
  box-shadow: var(--shadow-1);
}
.icon-btn:hover { filter: brightness(1.04); }
.icon-btn svg { width: 18px; height: 18px; }

/* Surfaces */
.card, article.doc {
  background: color-mix(in oklab, var(--panel) 96%, transparent);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow-2);
}
.card:hover { translate: 0 -1px; }
article.doc h1, article.doc h2, article.doc h3 { margin-top: 1.6em; margin-bottom: .6em; }
article.doc h1 { font-size: clamp(24px, 3.8vw, 30px); }
article.doc h2 { font-size: 1.1rem; color: var(--text); }
article.doc ul { padding-left: 1.2rem; }

/* Forms (for future use) */
input, select, textarea {
  background: color-mix(in oklab, var(--panel) 94%, transparent);
  border: 1px solid var(--border);
  border-radius: 12px;
  color: var(--text);
  padding: 10px 12px;
  outline: none;
  transition: box-shadow .2s ease, border-color .2s ease;
}
input:focus, select:focus, textarea:focus {
  box-shadow: 0 0 0 6px var(--ring);
  border-color: color-mix(in oklab, var(--accent) 45%, var(--border));
}

/* Tables */
table { width: 100%; border-collapse: collapse; border-radius: 12px; overflow: hidden; }
thead th { text-align: left; font-weight: 700; color: var(--muted); font-size: .9rem; }
th, td { padding: 12px 14px; border-bottom: 1px solid var(--border); }
tbody tr:hover { background: color-mix(in oklab, var(--panel) 92%, transparent); }

/* Footer */
.site-footer { margin-top: 56px; border-top: 1px solid var(--border); }
.footer-inner { padding: 24px; color: var(--muted); }

/* Utilities */
.grid { display: grid; gap: 14px; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
.kbd { display: inline-block; border: 1px solid var(--border); padding: 2px 6px; border-radius: 6px; font-variant: tabular-nums; background: color-mix(in oklab, var(--panel) 90%, transparent); }
code { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace; font-size: .95em; background: color-mix(in oklab, var(--panel) 90%, transparent); padding: 2px 6px; border-radius: 6px; }

/* Small screens */
@media (max-width: 560px) {
  .nav { display: none; }
  .container { padding: 18px; }
  .btn { width: 100%; }
}

/* Motion respect */
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}


/* === i18n toggle + brand icon === */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
}
.brand-icon {
  width: 20px;
  height: 20px;
  object-fit: contain;
  border-radius: 4px;
  box-shadow: 0 0 0 1px var(--border);
}
.brand-text { line-height: 1; }

/* Language toggle inherits .icon-btn; show 2-letter label */
.icon-btn .lang-label {
  font-weight: 600;
  letter-spacing: .05em;
}

/* Responsive: keep nav visible on small screens */
@media (max-width: 560px) {
  .header-inner { gap: 12px; }
  .nav { display: flex; flex-wrap: wrap; gap: 10px; }
  .brand-text { font-size: 16px; }
}