@layer base, components, utilities;

/* 베이스 스타일: CSS 초기화 및 전역 변수 설정 */
@layer base {
  :root {
    --bg-color: oklch(10% 0.05 260);
    --card-bg: oklch(20% 0.05 260 / 40%);
    --text-primary: oklch(98% 0.01 260);
    --text-secondary: oklch(75% 0.05 260);
    --primary-teal: oklch(75% 0.15 170);
    --glass: oklch(100% 0 0 / 3%);
    --border: oklch(100% 0 0 / 8%);
    --accent-glow: oklch(70% 0.2 170 / 15%);
  }

  * { box-sizing: border-box; margin: 0; padding: 0; }

  body {
    font-family: 'Pretendard', 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-color);
    background-image: 
        radial-gradient(circle at 10% 10%, oklch(60% 0.15 180 / 5%), transparent 40%),
        radial-gradient(circle at 90% 90%, oklch(60% 0.15 250 / 5%), transparent 40%);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.7;
    overflow-x: hidden;
    word-break: keep-all;
  }

  header {
    padding: 8rem 1.5rem 5rem;
    text-align: center;
    position: relative;
  }

  .logo {
    font-size: 1rem;
    font-weight: 900;
    letter-spacing: 0.5em;
    color: var(--primary-teal);
    margin-bottom: 2rem;
    text-transform: uppercase;
    text-shadow: 0 0 20px oklch(75% 0.15 170 / 30%);
  }

  h1 {
    font-size: clamp(3rem, 10vw, 5.5rem);
    font-weight: 900;
    letter-spacing: -0.05em;
    background: linear-gradient(135deg, #fff 20%, oklch(70% 0.05 260) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 2rem;
    line-height: 1;
  }

  .subtitle {
    color: var(--text-secondary);
    font-size: 1.2rem;
    max-width: 700px;
    margin: 0 auto;
    font-weight: 500;
    opacity: 0.9;
  }
}

/* 컴포넌트 스타일 */
@layer components {
  main {
    max-width: 1300px;
    margin: 0 auto;
    padding: 0 1.5rem 10rem;
  }

  .grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-bottom: 8rem;
  }

  .lesson-view {
    display: none;
    background: var(--card-bg);
    backdrop-filter: blur(40px);
    -webkit-backdrop-filter: blur(40px);
    border: 1px solid var(--border);
    border-radius: 3.5rem;
    padding: 4rem;
    box-shadow: 
        0 30px 60px -12px rgba(0, 0, 0, 0.6),
        inset 0 1px 1px oklch(100% 0 0 / 10%);
    margin-top: 2rem;
  }

  .lesson-view.active {
    display: block;
    animation: reveal 1s cubic-bezier(0.22, 1, 0.36, 1);
  }

  @keyframes reveal {
    from { opacity: 0; transform: translateY(40px) scale(0.97); filter: blur(10px); }
    to { opacity: 1; transform: translateY(0) scale(1); filter: blur(0); }
  }

  footer {
    padding: 6rem 1.5rem;
    text-align: center;
    border-top: 1px solid var(--border);
    color: var(--text-secondary);
    font-size: 0.95rem;
    background: oklch(5% 0 0 / 20%);
  }
}

/* 커스텀 스크롤바 */
::-webkit-scrollbar { width: 10px; }
::-webkit-scrollbar-track { background: var(--bg-color); }
::-webkit-scrollbar-thumb { 
    background: oklch(100% 0 0 / 10%); 
    border-radius: 20px;
    border: 2px solid var(--bg-color);
}
::-webkit-scrollbar-thumb:hover { background: oklch(100% 0 0 / 20%); }