/* ============================================================
   AI Trends Hub — Stylesheet
   모던하고 깔끔한 AI/테크 느낌의 반응형 디자인
   ============================================================ */

/* ---------- CSS Variables ---------- */
:root {
  /* 컬러 */
  --bg: #0f1117;
  --bg-card: #ffffff;
  --bg-soft: #f7f8fc;
  --bg-muted: #eef0f7;
  --text: #1a1d29;
  --text-soft: #5a6072;
  --text-muted: #8b91a3;
  --border: #e4e7ef;
  --border-soft: #eef0f7;

  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-light: #eef2ff;
  --accent: #a855f7;
  --accent-2: #ec4899;

  --gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 50%, #ec4899 100%);
  --gradient-soft: linear-gradient(135deg, #eef2ff 0%, #faf5ff 50%, #fdf2f8 100%);

  /* 카테고리 컬러 */
  --cat-agents: #6366f1;
  --cat-models: #f59e0b;
  --cat-coding: #10b981;
  --cat-research: #8b5cf6;
  --cat-industry: #ec4899;

  /* 크기 */
  --radius: 14px;
  --radius-sm: 8px;
  --radius-lg: 20px;
  --max-width: 1180px;
  --shadow-sm: 0 1px 3px rgba(15, 17, 23, 0.06);
  --shadow: 0 4px 16px rgba(15, 17, 23, 0.08);
  --shadow-lg: 0 12px 40px rgba(15, 17, 23, 0.12);
  --shadow-glow: 0 8px 32px rgba(99, 102, 241, 0.18);

  --transition: 0.22s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ---------- Reset ---------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Pretendard",
    "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
  background: var(--bg-soft);
  color: var(--text);
  line-height: 1.6;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

input, select {
  font-family: inherit;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.gradient-text {
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
}

/* ---------- 헤더 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border-soft);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 1.2rem;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.logo-icon {
  font-size: 1.4rem;
  filter: drop-shadow(0 0 8px rgba(99, 102, 241, 0.4));
}

.logo-text strong {
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.header-nav {
  display: flex;
  align-items: center;
  gap: 28px;
}

.header-nav a {
  color: var(--text-soft);
  font-size: 0.95rem;
  font-weight: 500;
  transition: color var(--transition);
}

.header-nav a:hover {
  color: var(--primary);
}

.bookmark-nav-btn {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 7px 14px;
  background: var(--primary-light);
  border-radius: 999px;
  color: var(--primary-dark);
  font-size: 0.9rem;
  font-weight: 600;
  transition: all var(--transition);
}

.bookmark-nav-btn:hover {
  background: var(--primary);
  color: #fff;
  transform: translateY(-1px);
}

.bookmark-nav-btn .icon {
  font-size: 1rem;
}

.bookmark-nav-btn .count {
  background: var(--primary);
  color: #fff;
  border-radius: 999px;
  padding: 1px 7px;
  font-size: 0.75rem;
  min-width: 20px;
  text-align: center;
}

.bookmark-nav-btn:hover .count {
  background: rgba(255, 255, 255, 0.25);
}

/* ---------- 히어로 ---------- */
.hero {
  position: relative;
  padding: 80px 0 64px;
  text-align: center;
  background: var(--gradient-soft);
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -40%;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 800px;
  background: radial-gradient(circle, rgba(168, 85, 247, 0.12), transparent 60%);
  pointer-events: none;
}

.hero-inner {
  position: relative;
  max-width: 720px;
}

.hero-badge {
  display: inline-block;
  padding: 6px 14px;
  background: rgba(255, 255, 255, 0.8);
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-soft);
  margin-bottom: 24px;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -0.03em;
  margin-bottom: 20px;
}

.hero-subtitle {
  font-size: clamp(1rem, 2.5vw, 1.15rem);
  color: var(--text-soft);
  margin-bottom: 40px;
  max-width: 560px;
  margin-left: auto;
  margin-right: auto;
}

/* ---------- 구독 폼 ---------- */
.subscribe-form {
  max-width: 480px;
  margin: 0 auto;
}

.subscribe-input-wrap {
  display: flex;
  gap: 8px;
  background: #fff;
  padding: 7px;
  border-radius: 999px;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
  transition: box-shadow var(--transition), transform var(--transition);
}

.subscribe-input-wrap:focus-within {
  box-shadow: var(--shadow-glow);
  transform: translateY(-2px);
}

.subscribe-input {
  flex: 1;
  border: none;
  background: transparent;
  padding: 12px 18px;
  font-size: 0.98rem;
  outline: none;
  color: var(--text);
  min-width: 0;
}

.subscribe-input::placeholder {
  color: var(--text-muted);
}

.subscribe-btn {
  flex-shrink: 0;
  background: var(--gradient);
  color: #fff;
  padding: 12px 24px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 0.95rem;
  transition: transform var(--transition), box-shadow var(--transition);
  white-space: nowrap;
}

.subscribe-btn:hover {
  transform: scale(1.04);
  box-shadow: var(--shadow-glow);
}

.subscribe-btn:active {
  transform: scale(0.98);
}

.subscribe-social-proof {
  margin-top: 16px;
  font-size: 0.88rem;
  color: var(--text-muted);
}

.subscribe-social-proof strong {
  color: var(--primary-dark);
}

.subscribe-message {
  margin-top: 14px;
  padding: 12px 18px;
  border-radius: var(--radius-sm);
  font-size: 0.92rem;
  font-weight: 500;
}

.subscribe-message.success {
  background: #ecfdf5;
  color: #065f46;
  border: 1px solid #a7f3d0;
}

.subscribe-message.error {
  background: #fef2f2;
  color: #991b1b;
  border: 1px solid #fecaca;
}

.subscribe-message.info {
  background: var(--primary-light);
  color: var(--primary-dark);
  border: 1px solid #c7d2fe;
}

/* ---------- 트렌드 섹션 ---------- */
.trends-section {
  padding: 56px 0 80px;
}

/* ---------- 컨트롤 바 ---------- */
.controls {
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin-bottom: 24px;
}

.filters {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.filter-btn {
  padding: 8px 16px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-soft);
  transition: all var(--transition);
}

.filter-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
  transform: translateY(-1px);
}

.filter-btn.active {
  background: var(--text);
  border-color: var(--text);
  color: #fff;
}

.search-sort-wrap {
  display: flex;
  gap: 12px;
  align-items: center;
}

.search-box {
  position: relative;
  flex: 1;
}

.search-icon {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 0.95rem;
  opacity: 0.6;
  pointer-events: none;
}

.search-input {
  width: 100%;
  padding: 11px 16px 11px 40px;
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 0.95rem;
  background: #fff;
  color: var(--text);
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.search-input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.12);
}

.search-input::placeholder {
  color: var(--text-muted);
}

.sort-select {
  padding: 11px 16px;
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-soft);
  background: #fff;
  cursor: pointer;
  outline: none;
  transition: border-color var(--transition);
}

.sort-select:hover {
  border-color: var(--primary);
}

/* ---------- 북마크 배너 ---------- */
.bookmark-banner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 20px;
  background: linear-gradient(135deg, #fef3c7, #fde68a);
  border: 1px solid #fcd34d;
  border-radius: var(--radius);
  margin-bottom: 20px;
  font-weight: 600;
  font-size: 0.95rem;
  color: #92400e;
}

.link-btn {
  color: var(--primary-dark);
  font-weight: 700;
  font-size: 0.9rem;
  text-decoration: underline;
  text-underline-offset: 2px;
}

/* ---------- 결과 정보 ---------- */
.result-info {
  margin-bottom: 20px;
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* ---------- 기사 그리드 ---------- */
.article-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

/* ---------- 기사 카드 ---------- */
.article-card {
  position: relative;
  display: flex;
  flex-direction: column;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  animation: cardFadeIn 0.4s ease both;
}

.article-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--border);
}

@keyframes cardFadeIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* 카테고리 상단 바 */
.card-category-bar {
  height: 4px;
  background: var(--primary);
}

.card-category-bar.Agents { background: var(--cat-agents); }
.card-category-bar.Models { background: var(--cat-models); }
.card-category-bar.Coding { background: var(--cat-coding); }
.card-category-bar.Research { background: var(--cat-research); }
.card-category-bar.Industry { background: var(--cat-industry); }

.card-body {
  display: flex;
  flex-direction: column;
  flex: 1;
  padding: 22px 22px 20px;
}

.card-meta-top {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
}

.category-tag {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.category-tag.Agents { background: rgba(99, 102, 241, 0.12); color: var(--cat-agents); }
.category-tag.Models { background: rgba(245, 158, 11, 0.12); color: var(--cat-models); }
.category-tag.Coding { background: rgba(16, 185, 129, 0.12); color: var(--cat-coding); }
.category-tag.Research { background: rgba(139, 92, 246, 0.12); color: var(--cat-research); }
.category-tag.Industry { background: rgba(236, 72, 153, 0.12); color: var(--cat-industry); }

.read-time {
  font-size: 0.78rem;
  color: var(--text-muted);
}

.card-title {
  font-size: 1.12rem;
  font-weight: 700;
  line-height: 1.4;
  letter-spacing: -0.02em;
  margin-bottom: 10px;
  color: var(--text);
  transition: color var(--transition);
}

.article-card:hover .card-title {
  color: var(--primary-dark);
}

.card-summary {
  font-size: 0.92rem;
  color: var(--text-soft);
  line-height: 1.6;
  margin-bottom: 16px;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 16px;
}

.card-tag {
  font-size: 0.75rem;
  color: var(--text-muted);
  background: var(--bg-muted);
  padding: 3px 9px;
  border-radius: var(--radius-sm);
}

.card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: auto;
  padding-top: 14px;
  border-top: 1px solid var(--border-soft);
}

.card-source {
  font-size: 0.82rem;
  color: var(--text-soft);
}

.card-source strong {
  color: var(--text);
  font-weight: 600;
}

.card-date {
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* 카드 액션 버튼 */
.card-actions {
  position: absolute;
  top: 14px;
  right: 14px;
  display: flex;
  gap: 6px;
  z-index: 2;
}

.action-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(4px);
  border: 1px solid var(--border);
  font-size: 0.95rem;
  color: var(--text-soft);
  transition: all var(--transition);
  opacity: 0;
  transform: translateY(-4px);
}

.article-card:hover .action-btn {
  opacity: 1;
  transform: translateY(0);
}

.action-btn:hover {
  background: #fff;
  border-color: var(--primary);
  color: var(--primary);
  transform: scale(1.1);
}

.action-btn.bookmarked {
  background: #fef3c7;
  border-color: #fcd34d;
  color: #d97706;
  opacity: 1;
  transform: translateY(0);
}

.action-btn.bookmarked:hover {
  color: #d97706;
  border-color: #f59e0b;
}

/* ---------- 빈 상태 ---------- */
.empty-state {
  text-align: center;
  padding: 80px 24px;
}

.empty-icon {
  font-size: 3.5rem;
  margin-bottom: 16px;
  opacity: 0.6;
}

.empty-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 8px;
}

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

/* ---------- 푸터 ---------- */
.site-footer {
  background: var(--bg);
  color: rgba(255, 255, 255, 0.7);
  padding: 48px 0 40px;
}

.footer-inner {
  text-align: center;
}

.footer-brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 1.1rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: 12px;
}

.footer-desc {
  font-size: 0.9rem;
  margin-bottom: 8px;
}

.footer-copy {
  font-size: 0.82rem;
  color: rgba(255, 255, 255, 0.4);
}

/* ---------- 토스트 ---------- */
.toast {
  position: fixed;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--text);
  color: #fff;
  padding: 14px 24px;
  border-radius: 999px;
  font-size: 0.92rem;
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  z-index: 1000;
  opacity: 0;
  transition: transform 0.35s cubic-bezier(0.34, 1.56, 0.64, 1), opacity 0.3s ease;
  pointer-events: none;
  white-space: nowrap;
}

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

/* ============================================================
   반응형
   ============================================================ */
@media (max-width: 900px) {
  .article-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 640px) {
  .container {
    padding: 0 16px;
  }

  .header-nav {
    gap: 16px;
  }

  .header-nav a {
    display: none;
  }

  .header-nav a:last-of-type,
  .bookmark-nav-btn {
    display: flex;
  }

  .hero {
    padding: 56px 0 48px;
  }

  .subscribe-input-wrap {
    flex-direction: column;
    border-radius: var(--radius);
    padding: 10px;
    gap: 8px;
  }

  .subscribe-input {
    text-align: center;
    padding: 14px;
  }

  .subscribe-btn {
    width: 100%;
    padding: 14px;
    border-radius: var(--radius-sm);
  }

  .article-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .search-sort-wrap {
    flex-direction: column;
    align-items: stretch;
  }

  .sort-select {
    width: 100%;
  }

  /* 모바일에서는 항상 액션 버튼 노출 */
  .action-btn {
    opacity: 1;
    transform: translateY(0);
  }
}