/**
 * 개인 기술 홈페이지 스타일시트 (assets/css/style.css)
 * 디자인 가이드(personal_website_design_guide.md)의 디자인 시스템을 정확히 구현합니다.
 * Modern Minimal / Editorial Technology Portfolio
 */

/* ==========================================================================
   1. CSS 변수 및 디자인 토큰
   ========================================================================== */
:root {
  /* 컬러 시스템 */
  --bg-main: #11151C;
  --bg-secondary: #1A202A;
  --bg-surface: #242C38;
  --bg-surface-hover: #2C3644;
  --bg-card: rgba(36, 44, 56, 0.75);

  --text-primary: #F4F5F7;
  --text-secondary: #AAB3C0;
  --text-muted: #7E8B9B;

  --accent: #F0A45A;
  --accent-hover: #FFB877;
  --accent-subtle: rgba(240, 164, 90, 0.12);
  --accent-border: rgba(240, 164, 90, 0.35);

  --border: #343E4B;
  --border-subtle: rgba(52, 62, 75, 0.5);

  /* 상태 색상 */
  --status-public-bg: rgba(62, 180, 137, 0.15);
  --status-public-text: #5fe3b3;
  --status-progress-bg: rgba(240, 164, 90, 0.15);
  --status-progress-text: #f0a45a;
  --status-confidential-bg: rgba(235, 115, 115, 0.15);
  --status-confidential-text: #f88787;
  --status-archive-bg: rgba(170, 179, 192, 0.12);
  --status-archive-text: #aab3c0;

  /* 타이포그래피 */
  --font-sans: -apple-system, BlinkMacSystemFont, "Pretendard", "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;

  /* 레이아웃 규격 */
  --container-max: 1160px;
  --header-height: 72px;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  /* 트랜지션 */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
  --transition-smooth: 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

/* ==========================================================================
   2. 기본 리셋 및 글로벌 스타일
   ========================================================================== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-height);
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-main);
  color: var(--text-primary);
  line-height: 1.7;
  letter-spacing: -0.01em;
  word-break: keep-all;
  overflow-x: hidden;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

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

ul, ol {
  list-style: none;
}

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

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

/* 스킵 링크 */
.skip-link {
  position: absolute;
  top: -60px;
  left: 20px;
  background: var(--accent);
  color: #11151c;
  padding: 12px 20px;
  font-weight: 700;
  border-radius: var(--radius-sm);
  z-index: 10000;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 16px;
}

/* ==========================================================================
   3. 레이아웃 컨테이너 & 섹션 공통
   ========================================================================== */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 40px;
}

.section {
  padding: 110px 0;
  position: relative;
}

.section-header {
  margin-bottom: 48px;
}

.section-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent);
  margin-bottom: 12px;
}

.section-title {
  font-size: 2.25rem;
  font-weight: 700;
  line-height: 1.3;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.section-subtitle {
  font-size: 1.125rem;
  color: var(--text-secondary);
  margin-top: 14px;
  max-width: 720px;
  line-height: 1.6;
}

.accent-text {
  color: var(--accent);
}

/* ==========================================================================
   4. 상단 고정 헤더 & 내비게이션
   ========================================================================== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background-color: rgba(17, 21, 28, 0.88);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-subtle);
  z-index: 1000;
  transition: background-color var(--transition-fast), border-color var(--transition-fast);
}

.site-header.scrolled {
  background-color: rgba(17, 21, 28, 0.96);
  border-bottom-color: var(--border);
}

.header-container {
  max-width: var(--container-max);
  height: 100%;
  margin: 0 auto;
  padding: 0 40px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--text-primary);
  text-decoration: none;
}

.logo-symbol-box {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  background-color: var(--bg-surface);
  border: 1px solid var(--accent);
  border-radius: var(--radius-sm);
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 1.125rem;
  font-weight: 800;
  line-height: 1;
  box-shadow: 0 0 10px rgba(240, 164, 90, 0.15);
  transition: all var(--transition-fast);
}

.brand-logo:hover .logo-symbol-box {
  background-color: var(--accent);
  color: #11151C;
  transform: translateY(-1px);
}

.logo-text-group {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
}

.logo-main-text {
  font-size: 1.125rem;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.logo-sub-text {
  font-family: var(--font-mono);
  font-size: 0.625rem;
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.12em;
  margin-top: 2px;
}

.logo-symbol-box.sm {
  width: 28px;
  height: 28px;
  font-size: 0.9375rem;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav-link {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
  padding: 6px 0;
  position: relative;
  transition: color var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
  color: var(--text-primary);
}

.nav-link.active::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 2px;
  background-color: var(--accent);
  border-radius: 2px;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.lang-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 14px;
  border-radius: var(--radius-sm);
  background-color: var(--bg-surface);
  border: 1px solid var(--border);
  color: var(--text-primary);
  font-size: 0.875rem;
  font-weight: 600;
  transition: all var(--transition-fast);
}

.lang-btn:hover {
  background-color: var(--bg-surface-hover);
  border-color: var(--accent);
  color: var(--accent);
}

/* 모바일 햄버거 토글 */
.mobile-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  padding: 8px;
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
  border: 1px solid var(--border);
  cursor: pointer;
}

.hamburger-line {
  display: block;
  width: 100%;
  height: 2px;
  background-color: var(--text-primary);
  border-radius: 2px;
  transition: transform var(--transition-normal), opacity var(--transition-fast);
}

.mobile-toggle[aria-expanded="true"] .hamburger-line:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.mobile-toggle[aria-expanded="true"] .hamburger-line:nth-child(2) {
  opacity: 0;
}
.mobile-toggle[aria-expanded="true"] .hamburger-line:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* 모바일 드롭다운 메뉴 */
.mobile-nav {
  display: none;
  position: absolute;
  top: var(--header-height);
  left: 0;
  right: 0;
  background-color: var(--bg-main);
  border-bottom: 1px solid var(--border);
  padding: 24px 32px;
  box-shadow: 0 12px 28px rgba(0, 0, 0, 0.4);
}

.mobile-nav.open {
  display: block;
}

.mobile-nav-links {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.mobile-nav-link {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-secondary);
  display: block;
  padding: 8px 0;
}

.mobile-nav-link:hover,
.mobile-nav-link.active {
  color: var(--accent);
}

/* ==========================================================================
   5. 버튼 스타일
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.9375rem;
  transition: all var(--transition-fast);
  text-align: center;
}

.btn-primary {
  background-color: var(--accent);
  color: #11151C;
  border: 1px solid var(--accent);
}

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

.btn-secondary {
  background-color: var(--bg-surface);
  color: var(--text-primary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background-color: var(--bg-surface-hover);
  border-color: var(--text-secondary);
  color: var(--text-primary);
}

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

.btn-outline:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.btn-sm {
  padding: 8px 14px;
  font-size: 0.8125rem;
}

/* ==========================================================================
   6. Hero 섹션
   ========================================================================== */
.hero-section {
  padding-top: 140px;
  padding-bottom: 100px;
  background: radial-gradient(circle at 80% 20%, rgba(240, 164, 90, 0.05) 0%, transparent 60%),
              var(--bg-main);
  border-bottom: 1px solid var(--border-subtle);
}

.hero-container {
  display: grid;
  grid-template-columns: 1.25fr 0.75fr;
  align-items: center;
  gap: 48px;
}

.section-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--accent);
  background-color: var(--accent-subtle);
  border: 1px solid var(--accent-border);
  padding: 6px 14px;
  border-radius: var(--radius-full);
  margin-bottom: 24px;
}

.hero-headline {
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: 18px;
  color: var(--text-primary);
}

.hero-subheadline {
  font-family: var(--font-mono);
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin-bottom: 20px;
  letter-spacing: -0.01em;
}

.hero-desc {
  font-size: 1.125rem;
  color: var(--text-secondary);
  line-height: 1.7;
  max-width: 620px;
  margin-bottom: 36px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 44px;
}

.hero-tags-wrapper {
  border-top: 1px solid var(--border-subtle);
  padding-top: 24px;
}

.hero-tags-label {
  display: block;
  font-size: 0.8125rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  margin-bottom: 12px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

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

.tech-tag {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  padding: 4px 10px;
  background-color: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.tech-tag:hover {
  border-color: var(--accent);
  color: var(--text-primary);
}

.hero-visual {
  display: flex;
  justify-content: center;
  align-items: center;
}

.abstract-graphic {
  width: 100%;
  max-width: 380px;
  height: auto;
  opacity: 0.85;
  transition: opacity var(--transition-normal);
}

.abstract-graphic:hover {
  opacity: 1;
}

/* ==========================================================================
   7. About 섹션
   ========================================================================== */
.about-section {
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-subtle);
}

.about-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 56px;
  align-items: flex-start;
}

.about-lead {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.6;
  margin-bottom: 24px;
}

.about-text-content p {
  color: var(--text-secondary);
  font-size: 1rem;
  margin-bottom: 18px;
}

.about-values {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.value-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 28px;
  position: relative;
  transition: border-color var(--transition-fast), transform var(--transition-fast);
}

.value-card:hover {
  border-color: var(--accent-border);
  transform: translateY(-2px);
}

.value-num {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 8px;
}

.value-title {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.value-desc {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ==========================================================================
   8. Expertise 섹션 (6개 분야 카드 그리드)
   ========================================================================== */
.expertise-section {
  background-color: var(--bg-main);
  border-bottom: 1px solid var(--border-subtle);
}

.expertise-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.expertise-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 32px 28px;
  display: flex;
  flex-direction: column;
  transition: all var(--transition-normal);
}

.expertise-card:hover {
  border-color: var(--accent);
  transform: translateY(-3px);
  background-color: var(--bg-surface-hover);
  box-shadow: 0 12px 28px rgba(0, 0, 0, 0.25);
}

.expertise-category-tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent);
  text-transform: uppercase;
  margin-bottom: 8px;
  letter-spacing: 0.05em;
}

.expertise-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 14px;
}

.expertise-desc {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 24px;
  flex-grow: 1;
}

.expertise-skills {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: auto;
  border-top: 1px solid var(--border-subtle);
  padding-top: 18px;
}

.skill-pill {
  font-size: 0.75rem;
  font-family: var(--font-mono);
  padding: 3px 8px;
  background-color: var(--bg-main);
  color: var(--text-secondary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
}

/* ==========================================================================
   9. Projects 섹션 (필터, 그리드, 카드)
   ========================================================================== */
.projects-section {
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-subtle);
}

.filter-wrapper {
  margin-bottom: 28px;
  overflow-x: auto;
  padding-bottom: 8px;
  -webkit-overflow-scrolling: touch;
}

.filter-tabs {
  display: flex;
  gap: 8px;
  min-width: max-content;
}

.filter-tab {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  padding: 8px 16px;
  border-radius: var(--radius-full);
  background-color: var(--bg-surface);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  font-weight: 500;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.filter-tab:hover {
  background-color: var(--bg-surface-hover);
  border-color: var(--text-secondary);
  color: var(--text-primary);
}

.filter-tab.active {
  background-color: var(--accent);
  border-color: var(--accent);
  color: #11151C;
  font-weight: 700;
}

.projects-meta-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
}

.project-count-badge {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--text-muted);
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.project-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 28px;
  display: flex;
  flex-direction: column;
  transition: all var(--transition-normal);
  cursor: pointer;
  position: relative;
}

.project-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
  box-shadow: 0 14px 30px rgba(0, 0, 0, 0.3);
  background-color: var(--bg-surface-hover);
}

.project-card-header {
  display: flex;
  align-items: center;
  margin-bottom: 12px;
}

.project-category-badge {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  background-color: var(--accent-subtle);
  border: 1px solid var(--accent-border);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  display: inline-block;
}

.project-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 12px;
  line-height: 1.4;
}

.project-summary {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 20px;
  flex-grow: 1;
}

.project-tech-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 20px;
}

.project-tech-tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 2px 8px;
  background-color: var(--bg-main);
  color: var(--text-secondary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
}

.project-footer {
  border-top: 1px solid var(--border-subtle);
  padding-top: 16px;
  display: flex;
  justify-content: flex-end;
}

.view-detail-btn {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  gap: 4px;
  transition: gap var(--transition-fast);
}

.project-card:hover .view-detail-btn {
  gap: 8px;
}

.no-projects-msg {
  text-align: center;
  padding: 60px 0;
  color: var(--text-muted);
  font-size: 1.125rem;
}

/* ==========================================================================
   10. AI & Research 섹션
   ========================================================================== */
.ai-section {
  background-color: var(--bg-main);
  border-bottom: 1px solid var(--border-subtle);
}

.ai-intro-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 28px 32px;
  margin-bottom: 32px;
}

.ai-intro-content {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.ai-intro-badge-row {
  margin-bottom: 8px;
}

.ai-intro-content p {
  color: var(--text-secondary);
  font-size: 1.0625rem;
  line-height: 1.7;
}

.ai-topics-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.ai-topic-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 28px;
  display: flex;
  flex-direction: column;
  transition: all var(--transition-normal);
}

.ai-topic-card:hover {
  border-color: var(--accent);
  transform: translateY(-3px);
  background-color: var(--bg-surface-hover);
}

.ai-topic-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}

.ai-index-pill {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 0.08em;
  background-color: var(--accent-subtle);
  border: 1px solid var(--accent-border);
  padding: 2px 8px;
  border-radius: var(--radius-sm);
}

.ai-type-pill {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  padding: 3px 8px;
  border-radius: var(--radius-full);
  font-weight: 600;
}

.ai-type-pill.commercial {
  background-color: var(--status-public-bg);
  color: var(--status-public-text);
  border: 1px solid rgba(95, 227, 179, 0.3);
}

.ai-type-pill.research {
  background-color: var(--status-progress-bg);
  color: var(--status-progress-text);
  border: 1px solid rgba(240, 164, 90, 0.3);
}

.ai-topic-title {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.ai-topic-desc {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ==========================================================================
   11. Contact 섹션
   ========================================================================== */
.contact-section {
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-subtle);
}

.contact-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 56px 48px;
}

.contact-details {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 48px;
  margin-top: 36px;
  border-top: 1px solid var(--border-subtle);
  padding-top: 36px;
}

.contact-box-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--accent);
  text-transform: uppercase;
  margin-bottom: 12px;
  letter-spacing: 0.05em;
}

.email-wrapper {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 16px;
}

.contact-email {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  border-bottom: 2px dashed var(--accent);
  padding-bottom: 2px;
}

.contact-email:hover {
  color: var(--accent);
}

.contact-notice {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.6;
}

.contact-links-box {
  display: flex;
  flex-direction: column;
}

.contact-links-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.external-links {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.ext-link {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 12px 18px;
  background-color: var(--bg-main);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-primary);
  transition: all var(--transition-fast);
}

.ext-link:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateX(3px);
}

/* ==========================================================================
   12. Footer
   ========================================================================== */
.site-footer {
  background-color: var(--bg-main);
  padding: 48px 0;
  margin-top: auto;
}

.footer-container {
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
  border-bottom: 1px solid var(--border-subtle);
  padding-bottom: 24px;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.footer-brand-title {
  display: flex;
  align-items: center;
  gap: 10px;
}

.footer-brand-name {
  font-size: 1.125rem;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.footer-brand-role {
  font-size: 0.8125rem;
  font-family: var(--font-mono);
  color: var(--accent);
  letter-spacing: 0.04em;
}

.footer-disclaimer {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-copy {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.footer-links {
  display: flex;
  align-items: center;
  gap: 20px;
}

.footer-link-btn,
.footer-link-anchor {
  font-size: 0.875rem;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.footer-link-btn:hover,
.footer-link-anchor:hover {
  color: var(--accent);
}

/* ==========================================================================
   13. 모달 (프로젝트 상세 & 개인정보처리방침)
   ========================================================================== */
.modal-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(9, 12, 16, 0.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  z-index: 2000;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-normal), visibility var(--transition-normal);
}

.modal-backdrop.open {
  opacity: 1;
  visibility: visible;
}

.modal-dialog {
  background-color: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  max-width: 680px;
  width: 100%;
  max-height: 85vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.6);
  transform: translateY(20px) scale(0.98);
  transition: transform var(--transition-smooth);
}

.modal-backdrop.open .modal-dialog {
  transform: translateY(0) scale(1);
}

.modal-header {
  padding: 24px 28px;
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

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

.modal-category-badge {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  background-color: var(--accent-subtle);
  border: 1px solid var(--accent-border);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
}

.modal-close-btn {
  font-size: 1.75rem;
  line-height: 1;
  color: var(--text-secondary);
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.modal-close-btn:hover {
  color: var(--text-primary);
  background-color: var(--bg-surface-hover);
}

.modal-body {
  padding: 28px;
  overflow-y: auto;
  flex-grow: 1;
}

.modal-title {
  font-size: 1.625rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 8px;
  line-height: 1.3;
}

.modal-domain-wrap {
  margin-bottom: 14px;
}

.modal-domain-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-muted);
  letter-spacing: 0.02em;
}

.modal-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 24px;
}

.modal-section {
  margin-bottom: 24px;
  border-top: 1px solid var(--border-subtle);
  padding-top: 18px;
}

.modal-section-title {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
  margin-bottom: 12px;
}

.modal-arch-box {
  background-color: var(--bg-main);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-sm);
  padding: 14px 18px;
  margin-bottom: 18px;
}

.modal-arch-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 6px;
}

.modal-arch-text {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--text-primary);
  line-height: 1.6;
}
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
  margin-bottom: 10px;
}

.modal-text {
  font-size: 0.9375rem;
  color: var(--text-primary);
  line-height: 1.7;
}

.modal-feature-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.modal-feature-list li {
  font-size: 0.9375rem;
  color: var(--text-primary);
  position: relative;
  padding-left: 18px;
}

.modal-feature-list li::before {
  content: "•";
  position: absolute;
  left: 4px;
  color: var(--accent);
}

.modal-tech-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.modal-footer {
  padding: 18px 28px;
  border-top: 1px solid var(--border-subtle);
  display: flex;
  justify-content: flex-end;
  background-color: rgba(26, 32, 42, 0.5);
}

/* ==========================================================================
   14. 반응형 미디어 쿼리
   ========================================================================== */

/* 태블릿 (768px ~ 1199px) */
@media (max-width: 1199px) {
  .expertise-grid,
  .projects-grid,
  .ai-topics-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .hero-container {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .hero-visual {
    display: none;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .contact-details {
    grid-template-columns: 1fr;
    gap: 36px;
  }
}

/* 모바일 (767px 이하) */
@media (max-width: 767px) {
  :root {
    --header-height: 64px;
  }

  .container,
  .header-container {
    padding: 0 20px;
  }

  .section {
    padding: 68px 0;
  }

  .hero-section {
    padding-top: 100px;
    padding-bottom: 60px;
  }

  .desktop-nav {
    display: none;
  }

  .mobile-toggle {
    display: flex;
  }

  .hero-headline {
    font-size: 2.375rem;
  }

  .hero-subheadline {
    font-size: 1.0625rem;
  }

  .hero-desc {
    font-size: 1rem;
  }

  .section-title {
    font-size: 1.75rem;
  }

  .section-subtitle {
    font-size: 1rem;
  }

  .expertise-grid,
  .projects-grid,
  .ai-topics-grid {
    grid-template-columns: 1fr;
    gap: 18px;
  }

  .project-card,
  .expertise-card,
  .ai-topic-card,
  .value-card {
    padding: 22px;
  }

  .contact-card {
    padding: 32px 20px;
  }

  .contact-email {
    font-size: 1.0625rem;
  }

  .footer-top,
  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
    gap: 14px;
  }

  .modal-dialog {
    max-height: 90vh;
  }

  .modal-header,
  .modal-body,
  .modal-footer {
    padding: 20px;
  }
}

/* ==========================================================================
   15. 사용자 모션 감소 지원 (접근성)
   ========================================================================== */
@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;
  }
}