/* =========================================================
   Vivon Labs – Shared Styles
   Docs-first · Trustworthy · Modern · Stable
   Background: FIXED overlay (banding/분리감 방지)
   ========================================================= */

/* ---------- Design Tokens ---------- */
:root {
  /* Colors */
  --bg: #0b1220;            /* base background */
  --card: #0f1a2e;          /* card surface */
  --text: #e7eefc;          /* primary text */
  --muted: #a9b6d3;         /* secondary text */
  --border: rgba(255,255,255,.10);
  --link: #8ab4ff;
  --link-hover: #b7d0ff;
  --accent: #22c55e;

  /* Layout */
  --maxw: 920px;
  --radius: 16px;
  --pad: 28px;

  /* Shadow */
  --shadow: 0 10px 30px rgba(0,0,0,.35);

  /* Font */
  --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas,
          "Liberation Mono", "Courier New", monospace;
}

/* ---------- Manual Theme Override (data-theme) ---------- */
/* 시스템 설정 대신 사용자가 강제로 고정하는 경우 */
@media (prefers-color-scheme: light) {
   :root[data-theme="dark"] {
     --bg: #0b1220;
     --card: #0f1a2e;
     --text: #e7eefc;
     --muted: #a9b6d3;
     --border: rgba(255,255,255,.10);
     --link: #8ab4ff;
     --link-hover: #b7d0ff;
     --shadow: 0 10px 30px rgba(0,0,0,.35);
   }

   :root[data-theme="light"] {
     --bg: #f6f8fc;
     --card: #ffffff;
     --text: #0b1220;
     --muted: #4a5568;
     --border: rgba(15, 23, 42, .10);
     --link: #2563eb;
     --link-hover: #1d4ed8;
     --shadow: 0 10px 30px rgba(15, 23, 42, .08);
   }

}

/* ---------- Base Reset ---------- */
* {
  box-sizing: border-box;
}

html, body {
  height: 100%;
  background: var(--bg); /* ✅ 단색 고정: 분리감 원천 차단 */
}

body {
  margin: 0;
  background: var(--bg); /* ✅ 단색 고정 */
  color: var(--text);
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial,
               "Noto Sans KR", sans-serif;
  line-height: 1.65;
  letter-spacing: -0.01em;
  position: relative;    /* ✅ ::before 오버레이 기준 */
  overflow-x: hidden;    /* ✅ 가로 스크롤 방지 */
}

/* ✅ FIXED 오버레이: 스크롤/페이지 높이 변화에도 "띠"가 생기지 않음 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;

  /* 어두운 배경에서 은은하게, 끝까지 자연스럽게 퍼지게 */
  background:
    radial-gradient(1400px 700px at 20% -10%, rgba(138,180,255,.10), transparent 100%),
    radial-gradient(1100px 550px at 90% -10%, rgba(34,197,94,.06), transparent 100%);
}

/* 라이트 모드에서는 tint를 더 약하게 (띠/단차 느낌 방지) */
@media (prefers-color-scheme: light) {
  body::before {
    background:
      radial-gradient(1400px 700px at 20% -10%, rgba(37,99,235,.06), transparent 100%),
      radial-gradient(1100px 550px at 90% -10%, rgba(34,197,94,.03), transparent 100%);
  }
}

/* ---------- Layout ---------- */
.container {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 48px 18px;
}

.card {
  background: linear-gradient(
    180deg,
    rgba(255,255,255,.06),
    rgba(255,255,255,.02)
  );
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: var(--pad);
}

/* ---------- Typography ---------- */
h1, h2, h3 {
  margin: 0.6em 0 0.35em;
  line-height: 1.25;
}

h1 { font-size: 32px; }

h2 {
  font-size: 20px;
  margin-top: 26px;
}

h3 {
  font-size: 16px;
  margin-top: 18px;
}

p { margin: 0.6em 0; }

small { color: var(--muted); }

hr {
  border: 0;
  border-top: 1px solid var(--border);
  margin: 22px 0;
}

/* ---------- Links ---------- */
a {
  color: var(--link);
  text-decoration: none;
}

a:hover {
  color: var(--link-hover);
  text-decoration: underline;
}

/* ---------- Lists ---------- */
ul, ol {
  margin: 10px 0 12px 20px;
}

li { margin: 6px 0; }

/* ---------- Notes / Callouts ---------- */
.note {
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 14px 16px;
  background: rgba(255,255,255,.04);
  color: var(--muted);
}

/* ---------- Buttons (Links) ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,.06);
  color: var(--text);
  text-decoration: none;
}

.btn:hover {
  background: rgba(255,255,255,.10);
  text-decoration: none;
}

/* ---------- Footer ---------- */
.footer {
  margin-top: 26px;
  color: var(--muted);
  font-size: 15px;
}

/* ---------- Code-like Text ---------- */
.code {
  font-family: var(--mono);
  font-size: 12.5px;
  padding: 2px 6px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: rgba(255,255,255,.04);
}

/* ---------- Mobile ---------- */
@media (max-width: 560px) {
  .container { padding: 32px 14px; }
  .card { padding: 18px; }
  h1 { font-size: 26px; }
}

/* ---------- Theme Floating Button (True Dual) ---------- */
.theme-fab {
  position: fixed;
  right: 16px;
  bottom: 16px;
  z-index: 9999;

  border: 1px solid var(--border);
  background: rgba(255,255,255,.06);
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);

  padding: 4px;
  border-radius: 999px;

  display: inline-flex;
  gap: 6px;
}

.theme-fab--dual .seg {
  width: 44px;
  height: 36px;
  border: 0;
  border-radius: 999px;

  display: inline-flex;
  align-items: center;
  justify-content: center;

  background: transparent;
  color: var(--muted);
  cursor: pointer;

  transition: background .12s ease, color .12s ease, box-shadow .12s ease, transform .12s ease;
}

.theme-fab--dual .seg:active { transform: translateY(1px); }

.theme-fab--dual .seg:focus {
  outline: 2px solid rgba(138,180,255,.35);
  outline-offset: 3px;
}

.theme-fab--dual .seg-icon {
  font-size: 16px;
  line-height: 1;
}

/* ✅ 하이라이트는 JS가 찍어주는 data-active로만 결정 */
#themeFab[data-active="dark"] .seg--dark {
  background: rgba(15, 26, 46, .85);
  color: #ffffff;
  box-shadow: 0 0 0 1px rgba(255,255,255,.08) inset;
}

#themeFab[data-active="light"] .seg--light {
  background: rgba(255,255,255,.92);
  color: #0b1220;
  box-shadow: 0 0 0 1px rgba(15,23,42,.10) inset;
}

/* Mobile */
@media (max-width: 560px) {
  .theme-fab { right: 12px; bottom: 12px; }
}