/* ============================================================
   생성형 AI 활용 교육 랜딩페이지 — style.css
   다크 테마 / 민트 액센트 / mobile-first
   ============================================================ */

/* ----- 디자인 토큰 (CSS 변수) ----- */
:root {
  /* 배경 */
  --bg-primary: #0D0D0D;
  --bg-secondary: #1A1A1A;
  --bg-elevated: #232323;

  /* 텍스트 */
  --text-primary: #F5F5F5;
  --text-secondary: #A3A3A3;
  --text-muted: #6B6B6B;

  /* 포인트 (밝은 민트/청록) */
  --accent: #5EEAD4;
  --accent-strong: #2DD4BF;
  --accent-dim: rgba(94, 234, 212, 0.12);

  /* 보더 */
  --border: rgba(255, 255, 255, 0.08);
  --border-strong: rgba(255, 255, 255, 0.16);

  /* 타이포 */
  --font-sans: "Pretendard Variable", "Pretendard", -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
  --font-display: "Space Grotesk", var(--font-sans);

  /* 레이아웃 */
  --container: 1200px;
  --gutter: 24px;
  --radius-card: 16px;
  --radius-btn: 12px;
  --radius-pill: 999px;

  /* 모션 */
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --dur: 250ms;

  /* 헤더 높이 */
  --header-h: 64px;
}

/* ----- 리셋 ----- */
*,
*::before,
*::after { box-sizing: border-box; }

* { margin: 0; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-h);
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-size: 1rem;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img, svg { display: block; max-width: 100%; }

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--dur) var(--ease);
}

ul, ol { list-style: none; padding: 0; }

button { font: inherit; cursor: pointer; }

code {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  background: var(--accent-dim);
  color: var(--accent);
  padding: 0.1em 0.45em;
  border-radius: 6px;
  font-size: 0.9em;
}

/* 스크린리더 전용 */
.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* 포커스 가시성 (접근성) */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

/* ----- 레이아웃 헬퍼 ----- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section { padding-block: clamp(64px, 10vw, 120px); }
.section--alt { background: var(--bg-secondary); }

.section__head {
  text-align: center;
  max-width: 640px;
  margin-inline: auto;
  margin-bottom: clamp(40px, 6vw, 64px);
}
.section__eyebrow {
  font-family: var(--font-display);
  text-transform: uppercase;
  letter-spacing: 0.18em;
  font-size: 0.8rem;
  color: var(--accent);
  margin-bottom: 12px;
}
.section__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.75rem, 3vw, 2.5rem);
  line-height: 1.2;
  letter-spacing: -0.01em;
}
.section__lead {
  margin-top: 14px;
  color: var(--text-secondary);
  font-size: 1.05rem;
}

/* ----- 버튼 ----- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  font-weight: 600;
  font-size: 0.95rem;
  line-height: 1;
  transition: transform var(--dur) var(--ease),
              box-shadow var(--dur) var(--ease),
              background-color var(--dur) var(--ease),
              border-color var(--dur) var(--ease),
              color var(--dur) var(--ease);
}
.btn--lg { padding: 16px 32px; font-size: 1.05rem; }

.btn--primary {
  background: var(--accent);
  color: #06201C;
}
.btn--primary:hover {
  transform: scale(1.02);
  box-shadow: 0 0 0 1px var(--accent-strong),
              0 8px 28px rgba(94, 234, 212, 0.35);
}

.btn--ghost {
  background: transparent;
  color: var(--text-primary);
  border-color: var(--border-strong);
}
.btn--ghost:hover {
  transform: scale(1.02);
  border-color: var(--accent);
  color: var(--accent);
}

.btn:disabled,
.btn[aria-disabled="true"] {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* ============================================================
   헤더 / 네비게이션
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(13, 13, 13, 0.72);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--border);
}
.nav {
  display: flex;
  align-items: center;
  gap: 24px;
  height: var(--header-h);
}
.nav__brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.05rem;
}
.nav__logo { color: var(--accent); }
.nav__menu {
  display: none;
  gap: 28px;
  margin-left: auto;
  font-size: 0.95rem;
  color: var(--text-secondary);
}
.nav__menu a:hover { color: var(--text-primary); }
.nav__cta { display: none; }

/* 모바일 햄버거 */
.nav__toggle {
  margin-left: auto;
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px; height: 44px;
  background: transparent;
  border: 0;
}
.nav__toggle span {
  display: block;
  width: 22px; height: 2px;
  margin-inline: auto;
  background: var(--text-primary);
  border-radius: 2px;
  transition: transform var(--dur) var(--ease), opacity var(--dur) var(--ease);
}
.nav__toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav__toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav__toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* 모바일 드롭다운 메뉴 */
.nav__menu.is-open {
  display: flex;
  flex-direction: column;
  position: absolute;
  top: var(--header-h);
  left: 0; right: 0;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  padding: 16px var(--gutter) 24px;
  gap: 4px;
}
.nav__menu.is-open li a {
  display: block;
  padding: 12px 4px;
  border-bottom: 1px solid var(--border);
}

/* ============================================================
   Hero
   ============================================================ */
.hero {
  position: relative;
  overflow: hidden;
  padding-block: clamp(80px, 16vw, 160px);
  background:
    radial-gradient(60% 60% at 50% 0%, rgba(94, 234, 212, 0.10), transparent 70%),
    var(--bg-primary);
}
.hero__inner { text-align: center; max-width: 820px; }
.hero__eyebrow {
  font-family: var(--font-display);
  letter-spacing: 0.08em;
  color: var(--accent);
  font-size: 0.9rem;
  margin-bottom: 20px;
}
.hero__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(2.5rem, 6vw, 5rem);
  line-height: 1.08;
  letter-spacing: -0.02em;
  min-height: 1.1em;
}
.hero__title-typed::after {
  content: "";
  display: inline-block;
  width: 0.06em;
  height: 1em;
  margin-left: 0.04em;
  background: var(--accent);
  vertical-align: -0.1em;
  animation: caret-blink 1s steps(1) infinite;
}
@keyframes caret-blink { 50% { opacity: 0; } }

.hero__subtitle {
  margin-top: 24px;
  font-size: clamp(1.1rem, 2vw, 1.4rem);
  color: var(--text-secondary);
}
.hero__actions {
  margin-top: 40px;
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  justify-content: center;
}
.hero__note {
  margin-top: 28px;
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* ============================================================
   카드 그리드 (개요 / 다운로드 / 후기 공용)
   ============================================================ */
.cards-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}
.card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  padding: 32px 28px;
  transition: transform var(--dur) var(--ease),
              border-color var(--dur) var(--ease),
              box-shadow var(--dur) var(--ease);
}
.card:hover {
  transform: translateY(-4px);
  border-color: var(--border-strong);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.4);
}
.card__icon { font-size: 2rem; margin-bottom: 16px; }
.card__title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 10px;
}
.card__desc { color: var(--text-secondary); font-size: 0.98rem; }

/* 다운로드 카드 */
.card--download { display: flex; flex-direction: column; align-items: flex-start; gap: 12px; }
.card--download .card__title,
.card--download .card__desc { margin-bottom: 0; }
.card--download .btn { margin-top: 8px; }
.badge {
  display: inline-block;
  font-size: 0.78rem;
  color: var(--accent);
  background: var(--accent-dim);
  border: 1px solid rgba(94, 234, 212, 0.25);
  padding: 5px 12px;
  border-radius: var(--radius-pill);
}

/* 후기 카드 */
.card--review { display: flex; flex-direction: column; gap: 16px; }
.review__stars { font-size: 0.95rem; letter-spacing: 0.05em; }
.review__quote {
  font-size: 1.05rem;
  line-height: 1.7;
  color: var(--text-primary);
}
.review__author {
  color: var(--text-muted);
  font-size: 0.9rem;
  font-weight: 500;
}

/* ============================================================
   커리큘럼 탭
   ============================================================ */
.tabs {
  display: inline-flex;
  gap: 6px;
  padding: 6px;
  margin-inline: auto;
  margin-bottom: 36px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-pill);
}
.tabs { display: flex; width: fit-content; }
.tab {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  border: 0;
  border-radius: var(--radius-pill);
  background: transparent;
  color: var(--text-secondary);
  font-weight: 600;
  transition: background-color var(--dur) var(--ease), color var(--dur) var(--ease);
}
.tab:hover { color: var(--text-primary); }
.tab.is-active {
  background: var(--accent);
  color: #06201C;
}
.tab__meta {
  font-size: 0.8rem;
  font-weight: 500;
}
.tabs-wrap { display: flex; justify-content: center; }

.tab-panel { animation: fade-up 400ms var(--ease); }
.tab-panel.is-hidden { display: none; }
.tab-panel__hint {
  text-align: center;
  color: var(--accent);
  font-size: 0.9rem;
  margin-bottom: 24px;
}

.module-list {
  display: grid;
  gap: 14px;
  max-width: 820px;
  margin-inline: auto;
}
.module {
  display: flex;
  align-items: flex-start;
  gap: 20px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  padding: 22px 24px;
  transition: border-color var(--dur) var(--ease), transform var(--dur) var(--ease);
}
.module:hover { border-color: var(--border-strong); transform: translateX(4px); }
.module__num {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.3rem;
  color: var(--accent);
  flex-shrink: 0;
  width: 2ch;
}
.module__title { font-size: 1.1rem; font-weight: 600; margin-bottom: 4px; }
.module__desc { color: var(--text-secondary); font-size: 0.95rem; }

/* ============================================================
   일정 타임라인
   ============================================================ */
.timeline {
  position: relative;
  max-width: 720px;
  margin-inline: auto;
  display: grid;
  gap: 28px;
  padding-left: 28px;
}
.timeline::before {
  content: "";
  position: absolute;
  left: 7px; top: 8px; bottom: 8px;
  width: 2px;
  background: var(--border-strong);
}
.timeline__item { position: relative; }
.timeline__marker {
  position: absolute;
  left: -28px; top: 6px;
  width: 16px; height: 16px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-dim);
}
.timeline__content {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  padding: 24px;
}
.timeline__badge {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-dim);
  padding: 4px 12px;
  border-radius: var(--radius-pill);
  margin-bottom: 12px;
}
.timeline__title { font-size: 1.3rem; font-weight: 600; margin-bottom: 8px; }
.timeline__meta { color: var(--text-primary); margin-bottom: 4px; }
.timeline__desc { color: var(--text-secondary); font-size: 0.95rem; }

/* ============================================================
   수강 신청
   ============================================================ */
.section--apply .section__head { margin-bottom: 32px; }
.apply-box {
  max-width: 560px;
  margin-inline: auto;
  text-align: center;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  padding: clamp(32px, 6vw, 48px);
}
.apply-box__deadline { color: var(--text-secondary); margin-bottom: 24px; }
.apply-box__deadline strong { color: var(--text-primary); }
.apply-box__contact { margin-top: 24px; color: var(--text-muted); font-size: 0.95rem; }

/* ============================================================
   Footer
   ============================================================ */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg-secondary);
  padding-block: 48px;
}
.site-footer__inner {
  display: flex;
  flex-direction: column;
  gap: 12px;
  align-items: center;
  text-align: center;
}
.site-footer__brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-display);
  font-weight: 700;
}
.site-footer__org { color: var(--text-secondary); font-size: 0.95rem; }
.site-footer__links { display: flex; gap: 20px; }
.site-footer__links a { color: var(--accent); font-size: 0.95rem; }
.site-footer__links a:hover { color: var(--accent-strong); }
.site-footer__slack { color: var(--text-secondary); font-size: 0.95rem; }
.site-footer__copy { color: var(--text-secondary); font-size: 0.85rem; margin-top: 4px; }

/* ============================================================
   스크롤 진입 애니메이션 (Step 3 JS와 연동)
   ============================================================ */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 600ms var(--ease), transform 600ms var(--ease);
}
.reveal.is-visible { opacity: 1; transform: none; }

@keyframes fade-up {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: none; }
}

/* ============================================================
   반응형 (mobile-first → 확장)
   ============================================================ */

/* 태블릿 이상 */
@media (min-width: 641px) {
  .cards-grid { grid-template-columns: repeat(2, 1fr); }
}

/* 데스크탑 */
@media (min-width: 1025px) {
  .nav__toggle { display: none; }
  .nav__menu { display: flex; margin-left: auto; }
  .nav__cta { display: inline-flex; }
  .cards-grid { grid-template-columns: repeat(3, 1fr); }
}

/* 모션 최소화 선호 사용자 */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  .hero__title-typed::after { animation: none; }
}