/* ==========================================================================
   THE ART OF VIBE CODING - DARK THEME STYLESHEET
   외부 이미지 없이 CSS만으로 구축된 모던 미니멀 다크 UI
   ========================================================================== */

/* 1. 디자인 시스템 토큰 */
:root {
  --bg-main: #090d16;
  --bg-secondary: #0f172a;
  --bg-card: #131d33;
  --bg-card-hover: #182542;
  --border-subtle: #1e293b;
  --border-accent: #334155;
  
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  
  --accent-cyan: #38bdf8;
  --accent-green: #34d399;
  --accent-purple: #818cf8;
  
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

/* 2. 전역 리셋 & 기본 세팅 */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  background-color: var(--bg-main);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 96px 0;
}

.section-darker {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-subtle);
  border-bottom: 1px solid var(--border-subtle);
}

.section-header {
  margin-bottom: 56px;
}

.section-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.12em;
  color: var(--accent-cyan);
  background-color: rgba(56, 189, 248, 0.08);
  border: 1px solid rgba(56, 189, 248, 0.2);
  padding: 4px 10px;
  border-radius: 9999px;
  margin-bottom: 14px;
}

.section-title {
  font-size: 2.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 650px;
  word-break: keep-all;
}

/* 3. 헤더 & 내비게이션 */
.header {
  position: sticky;
  top: 0;
  background: rgba(9, 13, 22, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-subtle);
  z-index: 100;
}

.nav-container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 24px;
  height: 64px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
}

.brand-logo {
  display: block;
  flex-shrink: 0;
  border: 1px solid rgba(56, 189, 248, 0.25);
  border-radius: 7px;
  box-shadow: 0 0 12px rgba(56, 189, 248, 0.15);
  transition: var(--transition);
}

.brand:hover .brand-logo {
  border-color: var(--accent-cyan);
  box-shadow: 0 0 18px rgba(56, 189, 248, 0.4);
  transform: translateY(-1px);
}

.brand-title {
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  display: flex;
  align-items: center;
}

.brand-white {
  color: #ffffff;
}

.brand-cyan {
  color: var(--accent-cyan);
}

.nav-links {
  display: flex;
  gap: 24px;
}

.nav-links a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: var(--transition);
}

.nav-links a:hover {
  color: var(--accent-cyan);
}

/* 4. 히어로 섹션 */
.hero {
  padding: 110px 0 90px;
  border-bottom: 1px solid var(--border-subtle);
  position: relative;
  overflow: hidden;
}

/* 순수 CSS 미니멀 그리드 배경 효과 */
.hero::before {
  content: "";
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: 1200px;
  height: 100%;
  background-image: 
    radial-gradient(circle at 50% 30%, rgba(56, 189, 248, 0.08) 0%, transparent 60%),
    linear-gradient(to right, rgba(255, 255, 255, 0.02) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(255, 255, 255, 0.02) 1px, transparent 1px);
  background-size: 100% 100%, 40px 40px, 40px 40px;
  pointer-events: none;
}

.hero-content {
  position: relative;
  text-align: center;
}

.hero-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent-purple);
  background: rgba(129, 140, 248, 0.1);
  border: 1px solid rgba(129, 140, 248, 0.25);
  padding: 6px 14px;
  border-radius: 9999px;
  margin-bottom: 24px;
}

.hero-title {
  font-size: 3.75rem;
  line-height: 1.15;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 24px;
}

.gradient-text {
  background: linear-gradient(135deg, var(--accent-cyan) 0%, var(--accent-purple) 50%, var(--accent-green) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-desc {
  font-size: 1.2rem;
  color: var(--text-secondary);
  max-width: 680px;
  margin: 0 auto 40px;
  word-break: keep-all;
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 16px;
}

/* 버튼 컴포넌트 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 28px;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.btn-primary {
  background-color: var(--accent-cyan);
  color: #030712;
  box-shadow: 0 0 20px rgba(56, 189, 248, 0.25);
}

.btn-primary:hover {
  background-color: #7dd3fc;
  box-shadow: 0 0 25px rgba(56, 189, 248, 0.4);
  transform: translateY(-2px);
}

.btn-ghost {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-accent);
}

.btn-ghost:hover {
  background: rgba(255, 255, 255, 0.05);
  border-color: var(--text-secondary);
  transform: translateY(-2px);
}

/* 5. 비교 카드 그리드 (Overview) */
.comparison-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 28px;
}

.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 36px 32px;
  transition: var(--transition);
}

.card:hover {
  border-color: var(--border-accent);
  background-color: var(--bg-card-hover);
}

.card-status {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  margin-bottom: 14px;
}

.status-muted {
  color: var(--text-muted);
}

.status-highlight {
  color: var(--accent-green);
}

.compare-card h3 {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 20px;
}

.vibe-way {
  border-color: rgba(52, 211, 153, 0.3);
  box-shadow: inset 0 0 30px rgba(52, 211, 153, 0.03);
}

.compare-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.compare-list li {
  position: relative;
  padding-left: 24px;
  color: var(--text-secondary);
  font-size: 0.95rem;
  word-break: keep-all;
}

.old-way .compare-list li::before {
  content: "—";
  position: absolute;
  left: 0;
  color: var(--text-muted);
}

.vibe-way .compare-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--accent-green);
  font-weight: bold;
}

/* 6. 5대 원칙 (Methodology) */
.rules-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.rule-item {
  display: flex;
  gap: 28px;
  padding: 32px;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  transition: var(--transition);
}

.rule-item:hover {
  border-color: var(--accent-cyan);
  transform: translateX(4px);
}

.rule-num {
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 800;
  color: var(--accent-cyan);
  line-height: 1;
  min-width: 44px;
}

.rule-body h3 {
  font-size: 1.25rem;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.rule-body p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-bottom: 12px;
  word-break: keep-all;
}

.rule-tip {
  display: inline-block;
  font-size: 0.85rem;
  color: var(--accent-green);
  background: rgba(52, 211, 153, 0.08);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
}

/* 7. 실전 프롬프트 치트시트 */
.prompts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(460px, 1fr));
  gap: 24px;
}

.prompt-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.prompt-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 20px;
  background: rgba(0, 0, 0, 0.2);
  border-bottom: 1px solid var(--border-subtle);
}

.prompt-badge {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-primary);
}

.copy-btn {
  background: var(--bg-secondary);
  color: var(--text-secondary);
  border: 1px solid var(--border-accent);
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

.copy-btn:hover {
  background: var(--accent-cyan);
  color: #000;
  border-color: var(--accent-cyan);
}

.prompt-code {
  padding: 20px;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.6;
  color: #cbd5e1;
  background: transparent;
  white-space: pre-wrap;
  word-break: break-word;
  flex: 1;
}

/* 8. 인터랙티브 퀴즈 / 자가진단 */
.quiz-container {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 32px;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 40px;
}

.quiz-items {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.quiz-item {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  cursor: pointer;
  user-select: none;
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

.quiz-item:hover {
  background: rgba(255, 255, 255, 0.03);
}

.quiz-check {
  display: none;
}

.check-box {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border-accent);
  border-radius: 4px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-top: 2px;
  flex-shrink: 0;
  transition: var(--transition);
}

.quiz-check:checked + .check-box {
  background-color: var(--accent-cyan);
  border-color: var(--accent-cyan);
}

.quiz-check:checked + .check-box::after {
  content: "✓";
  font-size: 13px;
  color: #000;
  font-weight: bold;
}

.quiz-text {
  font-size: 0.95rem;
  color: var(--text-secondary);
}

.score-display {
  background: rgba(0, 0, 0, 0.3);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 32px 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
}

.score-num {
  font-size: 4rem;
  font-weight: 800;
  color: var(--accent-cyan);
  line-height: 1;
  margin-bottom: 12px;
}

.score-num small {
  font-size: 1.25rem;
  color: var(--text-muted);
  font-weight: 400;
}

.score-level {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 10px;
}

.score-advice {
  font-size: 0.9rem;
  color: var(--text-muted);
  word-break: keep-all;
}

/* 9. 푸터 */
.footer {
  padding: 40px 0;
  border-top: 1px solid var(--border-subtle);
  background: var(--bg-main);
  text-align: center;
}

.footer-brand {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 800;
  letter-spacing: 0.05em;
  margin-bottom: 8px;
}

.footer-note {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* 10. 토스트 알림 */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: #10b981;
  color: #022c22;
  font-size: 0.9rem;
  font-weight: 600;
  padding: 10px 20px;
  border-radius: 9999px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.5);
  transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.3s ease;
  opacity: 0;
  pointer-events: none;
  z-index: 1000;
}

.toast.show {
  transform: translateX(-50%) translateY(0);
  opacity: 1;
}

/* 11. 반응형 스타일 */
@media (max-width: 820px) {
  .hero-title {
    font-size: 2.6rem;
  }
  
  .prompts-grid {
    grid-template-columns: 1fr;
  }

  .quiz-container {
    grid-template-columns: 1fr;
    padding: 24px;
  }
  
  .rule-item {
    flex-direction: column;
    gap: 12px;
  }
  
  .nav-links {
    display: none; /* 심플한 모바일 뷰 */
  }
}