/* 기본 색상 & 공통 변수 */
:root {
    --bg:       #0d0d0d;
    --surface:  rgba(255, 255, 255, 0.05);
    --fg:       #f5f5f5;
    --primary:  #ff3b30;
    --accent:   #2997ff;
    --radius:   8px;
  }
  
  /* Reset ‑‑ 간단히 여백·폰트 초기화 */
  * { box-sizing:border-box; margin:0; padding:0; }
  html,body { height:100%; }
  body {
    background:var(--bg);
    color:var(--fg);
    font-family:'Inter',sans-serif;
    line-height:1.6;
    -webkit-font-smoothing:antialiased;
  }
  
  /* 헤더 */
  header { text-align:center; padding:2.5rem 1rem; }
  header h1   { font-size:2.5rem; font-weight:600; letter-spacing:-.02em; }
  header .subtitle { margin-top:.5rem; font-size:1rem; opacity:.8; }
  
  /* 내비게이션 */
  nav ul {
    display:flex; flex-wrap:wrap; justify-content:center; gap:1rem;
    margin-top:2rem; list-style:none;
  }
  nav a {
    color:var(--accent); text-decoration:none;
    padding:.5rem 1rem; border-radius:var(--radius);
    transition:background .3s;
  }
  nav a:hover { background:var(--surface); }
  nav li.cta a {
    background:var(--primary); color:#fff; font-weight:600;
  }
  nav li.cta a:hover { background:#e32620; }
  
  /* 섹션 */
  section {
    max-width:800px; margin:0 auto 3rem;
    padding:2rem 1.5rem; background:var(--surface);
    border-radius:var(--radius);
  }
  section h2 { font-size:1.75rem; margin-bottom:1rem; }
  section p  { opacity:.9; }
  
  /* 버튼 스타일 */
  .btn {
    display:inline-block; margin-top:1.25rem;
    background:var(--primary); color:#fff; text-decoration:none;
    padding:.75rem 1.5rem; border-radius:var(--radius);
    transition:background .3s;
  }
  .btn:hover { background:#e32620; }
  
  /* 푸터 */
  footer {
    text-align:center; padding:2.5rem 1rem;
    background:#111; font-size:.875rem;
  }
  footer .age    { font-weight:600; color:var(--primary); }
  footer .notice { opacity:.7; margin-top:.25rem; }
  
  /* 라이트 모드 대비 */
  @media (prefers-color-scheme: light) {
    body      { background:#fff; color:#111; }
    section   { background:rgba(0,0,0,0.05); }
    nav a     { color:var(--accent); }
    nav a:hover { background:rgba(0,0,0,0.08); }
    footer    { background:#f5f5f5; }
  }