/* ==========================================================================
   화학안전 인포그래픽 대시보드 - CSS 디자인 시스템
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Pretendard:wght@300;400;500;600;700;800;900&family=JetBrains+Mono:wght@400;600;700&display=swap');

:root {
  /* 테마 컬러 (다크 모드 기본) */
  --bg-primary: #0a0d14;
  --bg-secondary: #111726;
  --bg-card: rgba(18, 24, 38, 0.75);
  --bg-card-hover: rgba(26, 35, 56, 0.85);
  --bg-card-active: rgba(30, 41, 67, 0.95);
  
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-medium: rgba(255, 255, 255, 0.16);
  --border-bright: rgba(255, 255, 255, 0.3);

  --text-main: #f1f5f9;
  --text-muted: #94a3b8;
  --text-dim: #64748b;

  --accent-cyan: #38bdf8;
  --accent-blue: #3b82f6;

  /* 카테고리별 테마 액센트 컬러 */
  --color-acid: #f43f5e;       /* 산성 */
  --color-base: #06b6d4;       /* 염기 */
  --color-toxic: #10b981;      /* 독성 */
  --color-flammable: #f97316;  /* 가연 */
  --color-metal: #eab308;      /* 금속 */
  --color-oil: #ef4444;        /* 유류 */
  --color-gas: #6366f1;        /* 가스 */
  --color-confined: #a855f7;   /* 밀폐 */

  --font-sans: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 16px 36px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 25px rgba(56, 189, 248, 0.25);

  --transition-fast: 0.18s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.28s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-bounce: 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* Light Theme Variables */
[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #f1f5f9;
  --bg-card: rgba(255, 255, 255, 0.85);
  --bg-card-hover: rgba(241, 245, 249, 0.95);
  --bg-card-active: #ffffff;

  --border-subtle: rgba(0, 0, 0, 0.08);
  --border-medium: rgba(0, 0, 0, 0.15);
  --border-bright: rgba(0, 0, 0, 0.25);

  --text-main: #0f172a;
  --text-muted: #475569;
  --text-dim: #94a3b8;

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 8px 24px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 16px 36px rgba(15, 23, 42, 0.12);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-main);
  min-height: 100vh;
  line-height: 1.5;
  background-image: 
    radial-gradient(circle at 15% 10%, rgba(56, 189, 248, 0.05) 0%, transparent 40%),
    radial-gradient(circle at 85% 85%, rgba(168, 85, 247, 0.04) 0%, transparent 45%);
  background-attachment: fixed;
  overflow-x: hidden;
}

/* Layout */
.app-container {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  padding: 16px 24px;
  gap: 16px;
  max-width: 1920px;
  margin: 0 auto;
}

/* Header */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 20px;
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  flex-wrap: wrap;
  gap: 14px;
}

.brand-section {
  display: flex;
  align-items: center;
  gap: 14px;
}

.brand-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, #0ea5e9, #6366f1);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  box-shadow: 0 4px 14px rgba(14, 165, 233, 0.35);
}

.brand-title h1 {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  background: linear-gradient(90deg, #38bdf8, #818cf8, #c084fc);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  display: flex;
  align-items: center;
  gap: 8px;
}

.brand-title p {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 500;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.search-box {
  position: relative;
  width: 260px;
}

.search-box input {
  width: 100%;
  padding: 8px 14px 8px 36px;
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  color: var(--text-main);
  font-size: 0.85rem;
  outline: none;
  transition: var(--transition-fast);
}

[data-theme="light"] .search-box input {
  background: rgba(0, 0, 0, 0.05);
}

.search-box input:focus {
  border-color: var(--accent-cyan);
  box-shadow: 0 0 10px rgba(56, 189, 248, 0.25);
  background: rgba(0, 0, 0, 0.3);
}

.search-icon {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 0.85rem;
  color: var(--text-dim);
  pointer-events: none;
}

.btn-header {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  border-radius: var(--radius-full);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  border: 1px solid var(--border-subtle);
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-main);
  transition: var(--transition-fast);
  user-select: none;
}

.btn-header:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: var(--border-medium);
  transform: translateY(-1px);
}

.btn-toc {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.2), rgba(168, 85, 247, 0.2));
  border-color: rgba(99, 102, 241, 0.4);
  color: #c4b5fd;
}
.btn-toc:hover {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.35), rgba(168, 85, 247, 0.35));
  box-shadow: 0 0 16px rgba(168, 85, 247, 0.3);
  color: #fff;
}

/* ==========================================================================
   핵심: 8대 카테고리 버튼 바 (산성/염기/독성/가연/금속/유류/가스/밀폐)
   ========================================================================== */
.categories-nav-wrapper {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 12px 16px;
  box-shadow: var(--shadow-sm);
}

.nav-header-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
  padding: 0 4px;
}

.nav-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.nav-hint {
  font-size: 0.75rem;
  color: var(--text-dim);
  font-family: var(--font-mono);
}

.nav-hint kbd {
  background: rgba(255, 255, 255, 0.1);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.7rem;
  border: 1px solid var(--border-subtle);
}

/* 8대 버튼 그리드/플렉스 */
.categories-bar {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  gap: 10px;
  width: 100%;
}

.cat-btn {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 14px 8px 12px;
  background: rgba(255, 255, 255, 0.03);
  border: 1.5px solid var(--border-subtle);
  border-radius: var(--radius-md);
  color: var(--text-muted);
  cursor: pointer;
  transition: all var(--transition-normal);
  text-align: center;
  overflow: hidden;
  user-select: none;
}

.cat-btn::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: transparent;
  transition: background var(--transition-fast);
}

.cat-btn:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-medium);
  transform: translateY(-2px);
  color: var(--text-main);
  box-shadow: var(--shadow-sm);
}

/* 키 번호 뱃지 (1~8) */
.cat-btn .btn-badge-num {
  position: absolute;
  top: 6px;
  left: 8px;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 700;
  opacity: 0.5;
  letter-spacing: 0.02em;
}

.cat-btn .btn-icon-box {
  font-size: 1.5rem;
  margin-bottom: 6px;
  filter: drop-shadow(0 2px 6px rgba(0,0,0,0.3));
  transition: transform var(--transition-bounce);
}

.cat-btn:hover .btn-icon-box {
  transform: scale(1.15);
}

.cat-btn .btn-label {
  font-size: 1.05rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  margin-bottom: 3px;
  color: inherit;
}

.cat-btn .btn-count-tag {
  font-size: 0.7rem;
  font-weight: 600;
  padding: 2px 6px;
  border-radius: var(--radius-full);
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-dim);
  transition: var(--transition-fast);
}

/* 활성화 상태 (Active 버튼 스타일) */
.cat-btn.active {
  background: var(--bg-card-active);
  color: #ffffff;
  transform: translateY(-3px);
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.5);
}

/* 카테고리별 고유 색상 테마 적용 */
/* 1. 산성 */
.cat-btn[data-cat="acid"].active,
.cat-btn[data-cat="acid"]:hover {
  border-color: var(--color-acid);
}
.cat-btn[data-cat="acid"]::before { background: var(--color-acid); }
.cat-btn[data-cat="acid"].active {
  box-shadow: 0 8px 24px -4px rgba(244, 63, 94, 0.45);
  border-color: var(--color-acid);
  background: linear-gradient(180deg, rgba(244, 63, 94, 0.2) 0%, rgba(20, 26, 42, 0.95) 100%);
}
.cat-btn[data-cat="acid"].active .btn-label { color: #fda4af; }
.cat-btn[data-cat="acid"].active .btn-count-tag { background: rgba(244, 63, 94, 0.25); color: #ffe4e6; }

/* 2. 염기 */
.cat-btn[data-cat="base"].active,
.cat-btn[data-cat="base"]:hover {
  border-color: var(--color-base);
}
.cat-btn[data-cat="base"]::before { background: var(--color-base); }
.cat-btn[data-cat="base"].active {
  box-shadow: 0 8px 24px -4px rgba(6, 182, 212, 0.45);
  border-color: var(--color-base);
  background: linear-gradient(180deg, rgba(6, 182, 212, 0.2) 0%, rgba(20, 26, 42, 0.95) 100%);
}
.cat-btn[data-cat="base"].active .btn-label { color: #67e8f9; }
.cat-btn[data-cat="base"].active .btn-count-tag { background: rgba(6, 182, 212, 0.25); color: #cffafe; }

/* 3. 독성 */
.cat-btn[data-cat="toxic"].active,
.cat-btn[data-cat="toxic"]:hover {
  border-color: var(--color-toxic);
}
.cat-btn[data-cat="toxic"]::before { background: var(--color-toxic); }
.cat-btn[data-cat="toxic"].active {
  box-shadow: 0 8px 24px -4px rgba(16, 185, 129, 0.45);
  border-color: var(--color-toxic);
  background: linear-gradient(180deg, rgba(16, 185, 129, 0.2) 0%, rgba(20, 26, 42, 0.95) 100%);
}
.cat-btn[data-cat="toxic"].active .btn-label { color: #6ee7b7; }
.cat-btn[data-cat="toxic"].active .btn-count-tag { background: rgba(16, 185, 129, 0.25); color: #d1fae5; }

/* 4. 가연 */
.cat-btn[data-cat="flammable"].active,
.cat-btn[data-cat="flammable"]:hover {
  border-color: var(--color-flammable);
}
.cat-btn[data-cat="flammable"]::before { background: var(--color-flammable); }
.cat-btn[data-cat="flammable"].active {
  box-shadow: 0 8px 24px -4px rgba(249, 115, 22, 0.45);
  border-color: var(--color-flammable);
  background: linear-gradient(180deg, rgba(249, 115, 22, 0.2) 0%, rgba(20, 26, 42, 0.95) 100%);
}
.cat-btn[data-cat="flammable"].active .btn-label { color: #fdba74; }
.cat-btn[data-cat="flammable"].active .btn-count-tag { background: rgba(249, 115, 22, 0.25); color: #ffedd5; }

/* 5. 금속 */
.cat-btn[data-cat="metal"].active,
.cat-btn[data-cat="metal"]:hover {
  border-color: var(--color-metal);
}
.cat-btn[data-cat="metal"]::before { background: var(--color-metal); }
.cat-btn[data-cat="metal"].active {
  box-shadow: 0 8px 24px -4px rgba(234, 179, 8, 0.45);
  border-color: var(--color-metal);
  background: linear-gradient(180deg, rgba(234, 179, 8, 0.2) 0%, rgba(20, 26, 42, 0.95) 100%);
}
.cat-btn[data-cat="metal"].active .btn-label { color: #fde047; }
.cat-btn[data-cat="metal"].active .btn-count-tag { background: rgba(234, 179, 8, 0.25); color: #fef9c3; }

/* 6. 유류 */
.cat-btn[data-cat="oil"].active,
.cat-btn[data-cat="oil"]:hover {
  border-color: var(--color-oil);
}
.cat-btn[data-cat="oil"]::before { background: var(--color-oil); }
.cat-btn[data-cat="oil"].active {
  box-shadow: 0 8px 24px -4px rgba(239, 68, 68, 0.45);
  border-color: var(--color-oil);
  background: linear-gradient(180deg, rgba(239, 68, 68, 0.2) 0%, rgba(20, 26, 42, 0.95) 100%);
}
.cat-btn[data-cat="oil"].active .btn-label { color: #fca5a5; }
.cat-btn[data-cat="oil"].active .btn-count-tag { background: rgba(239, 68, 68, 0.25); color: #fee2e2; }

/* 7. 가스 */
.cat-btn[data-cat="gas"].active,
.cat-btn[data-cat="gas"]:hover {
  border-color: var(--color-gas);
}
.cat-btn[data-cat="gas"]::before { background: var(--color-gas); }
.cat-btn[data-cat="gas"].active {
  box-shadow: 0 8px 24px -4px rgba(99, 102, 241, 0.45);
  border-color: var(--color-gas);
  background: linear-gradient(180deg, rgba(99, 102, 241, 0.2) 0%, rgba(20, 26, 42, 0.95) 100%);
}
.cat-btn[data-cat="gas"].active .btn-label { color: #a5b4fc; }
.cat-btn[data-cat="gas"].active .btn-count-tag { background: rgba(99, 102, 241, 0.25); color: #e0e7ff; }

/* 8. 밀폐 */
.cat-btn[data-cat="confined"].active,
.cat-btn[data-cat="confined"]:hover {
  border-color: var(--color-confined);
}
.cat-btn[data-cat="confined"]::before { background: var(--color-confined); }
.cat-btn[data-cat="confined"].active {
  box-shadow: 0 8px 24px -4px rgba(168, 85, 247, 0.45);
  border-color: var(--color-confined);
  background: linear-gradient(180deg, rgba(168, 85, 247, 0.2) 0%, rgba(20, 26, 42, 0.95) 100%);
}
.cat-btn[data-cat="confined"].active .btn-label { color: #d8b4fe; }
.cat-btn[data-cat="confined"].active .btn-count-tag { background: rgba(168, 85, 247, 0.25); color: #f3e8ff; }


/* ==========================================================================
   메인 대시보드 콘텐츠 영역 (상세 정보 카드 + PDF 뷰어)
   ========================================================================== */
.main-content {
  display: grid;
  grid-template-columns: 360px 1fr;
  gap: 16px;
  flex: 1;
  min-height: calc(100vh - 220px);
}

/* 좌측 상세 인포 패널 */
.info-sidebar {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.category-detail-card {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 20px;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 16px;
  transition: border-color var(--transition-fast);
}

.detail-header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--border-subtle);
}

.detail-icon-circle {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8rem;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-medium);
  box-shadow: var(--shadow-sm);
  flex-shrink: 0;
}

.detail-title-group h2 {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.detail-title-group .eng-sub {
  font-size: 0.75rem;
  color: var(--text-dim);
  font-family: var(--font-mono);
  text-transform: uppercase;
}

.section-block {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.section-block h3 {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 6px;
}

/* 물질 태그 목록 */
.substance-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.substance-tag {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 12px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-main);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.substance-tag:hover {
  background: rgba(255, 255, 255, 0.12);
  border-color: var(--border-medium);
  transform: translateY(-1px);
}

.substance-tag.highlight {
  border-color: var(--accent-cyan);
  background: rgba(56, 189, 248, 0.18);
  color: #38bdf8;
  font-weight: 700;
  box-shadow: 0 0 12px rgba(56, 189, 248, 0.3);
}

/* 위험성 & 행동 요령 블록 */
.hazard-box {
  padding: 12px 14px;
  border-radius: var(--radius-md);
  background: rgba(244, 63, 94, 0.08);
  border: 1px solid rgba(244, 63, 94, 0.2);
  font-size: 0.82rem;
  color: #fecdd3;
  line-height: 1.45;
}

.actions-box {
  padding: 12px 14px;
  border-radius: var(--radius-md);
  background: rgba(56, 189, 248, 0.08);
  border: 1px solid rgba(56, 189, 248, 0.2);
  font-size: 0.82rem;
  color: #bae6fd;
  line-height: 1.45;
}

/* 우측 PDF 뷰어 컨테이너 */
.viewer-container {
  display: flex;
  flex-direction: column;
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
  height: 100%;
}

.viewer-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 16px;
  background: rgba(0, 0, 0, 0.2);
  border-bottom: 1px solid var(--border-subtle);
  flex-wrap: wrap;
  gap: 8px;
}

[data-theme="light"] .viewer-toolbar {
  background: rgba(0, 0, 0, 0.03);
}

.toolbar-file-info {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-main);
  max-width: 60%;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.toolbar-file-info .file-badge {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  padding: 2px 6px;
  border-radius: 4px;
  background: rgba(239, 68, 68, 0.2);
  color: #f87171;
  font-weight: 700;
}

.toolbar-btn-group {
  display: flex;
  align-items: center;
  gap: 8px;
}

.tool-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-subtle);
  color: var(--text-muted);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition-fast);
  text-decoration: none;
}

.tool-btn:hover {
  background: rgba(255, 255, 255, 0.12);
  border-color: var(--border-medium);
  color: var(--text-main);
}

.tool-btn.primary {
  background: linear-gradient(135deg, rgba(14, 165, 233, 0.3), rgba(99, 102, 241, 0.3));
  border-color: rgba(56, 189, 248, 0.4);
  color: #7dd3fc;
}
.tool-btn.primary:hover {
  background: linear-gradient(135deg, rgba(14, 165, 233, 0.5), rgba(99, 102, 241, 0.5));
  color: #fff;
}

.pdf-viewport {
  flex: 1;
  position: relative;
  background: #1e2433;
  min-height: 600px;
}

.pdf-frame {
  width: 100%;
  height: 100%;
  min-height: 680px;
  border: none;
  display: block;
}

/* 로딩 스피너 및 알림 */
.viewer-fallback {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  color: var(--text-muted);
  pointer-events: none;
}

/* ==========================================================================
   모달 (전체 목차 등)
   ========================================================================== */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-normal);
  padding: 20px;
}

.modal-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

.modal-window {
  background: var(--bg-secondary);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-xl);
  width: 100%;
  max-width: 900px;
  height: 85vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  transform: scale(0.96);
  transition: transform var(--transition-normal);
}

.modal-overlay.active .modal-window {
  transform: scale(1);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 24px;
  border-bottom: 1px solid var(--border-subtle);
  background: var(--bg-card);
}

.modal-header h3 {
  font-size: 1.15rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 8px;
}

.btn-close-modal {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-subtle);
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  transition: var(--transition-fast);
}

.btn-close-modal:hover {
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
}

.modal-body {
  flex: 1;
  position: relative;
  background: #111827;
}

.modal-iframe {
  width: 100%;
  height: 100%;
  border: none;
}

/* ==========================================================================
   미디어 쿼리 (반응형 대응)
   ========================================================================== */
@media (max-width: 1400px) {
  .categories-bar {
    grid-template-columns: repeat(4, 1fr);
  }
}

@media (max-width: 1024px) {
  .main-content {
    grid-template-columns: 1fr;
  }
  .info-sidebar {
    order: 2;
  }
  .viewer-container {
    order: 1;
    min-height: 550px;
  }
}

@media (max-width: 640px) {
  .app-container {
    padding: 10px;
  }
  .categories-bar {
    grid-template-columns: repeat(2, 1fr);
  }
  .app-header {
    flex-direction: column;
    align-items: stretch;
  }
  .search-box {
    width: 100%;
  }
}