/* ===================================================================
   Sungwon's Lab & Life — Blog Theme
   A refined editorial design with warmth
   =================================================================== */

/* --- Reset & Variables --- */
:root {
  --font-display: 'DM Serif Display', Georgia, serif;
  --font-body: 'IBM Plex Sans KR', -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  --color-bg: #f0f4f8;
  --color-surface: #ffffff;
  --color-text: #1e293b;
  --color-text-muted: #64748b;
  --color-accent: #2563eb;
  --color-accent-soft: #dbeafe;
  --color-research: #1e40af;
  --color-research-soft: #dbeafe;
  --color-tech: #0369a1;
  --color-tech-soft: #e0f2fe;
  --color-trip: #0d9488;
  --color-trip-soft: #ccfbf1;
  --color-food: #7c3aed;
  --color-food-soft: #ede9fe;
  --color-border: #cbd5e1;
  --color-code-bg: #1e293b;

  --max-width: 1120px;
  --content-width: 720px;
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --space-2xl: 5rem;

  --radius: 8px;
  --radius-lg: 14px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.1);
}

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

html {
  font-size: 17px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color 0.2s;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* --- Header --- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(240, 244, 248, 0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0.9rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--font-display);
  font-size: 1.25rem;
  letter-spacing: -0.02em;
}

.logo-icon {
  font-size: 1.4rem;
  color: var(--color-accent);
}

.site-nav {
  display: flex;
  gap: 0.25rem;
}

.nav-link {
  padding: 0.45rem 0.9rem;
  border-radius: 6px;
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--color-text-muted);
  transition: all 0.2s;
}

.nav-link:hover {
  color: var(--color-text);
  background: rgba(0,0,0,0.04);
}

.nav-link--active {
  color: var(--color-accent);
  background: var(--color-accent-soft);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--color-text);
  transition: 0.3s;
}

/* --- Main --- */
.site-main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-xl) 1.5rem;
  min-height: 60vh;
}

/* --- Hero Section (Home) --- */
.hero {
  text-align: center;
  padding: var(--space-2xl) 0 var(--space-xl);
  position: relative;
}

.hero::before {
  content: '';
  position: absolute;
  top: -40px;
  left: 50%;
  transform: translateX(-50%);
  width: 200px;
  height: 200px;
  background: radial-gradient(circle, var(--color-accent-soft) 0%, transparent 70%);
  z-index: -1;
  opacity: 0.7;
}

.hero__title {
  font-family: var(--font-display);
  font-size: clamp(2.2rem, 5vw, 3.2rem);
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: var(--space-md);
}

.hero__title em {
  font-style: normal;
  color: var(--color-accent);
}

.hero__desc {
  font-size: 1.05rem;
  color: var(--color-text-muted);
  max-width: 520px;
  margin: 0 auto;
  line-height: 1.65;
}

/* --- Section Headers --- */
.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--color-border);
}

.section-title {
  font-family: var(--font-display);
  font-size: 1.5rem;
  letter-spacing: -0.02em;
}

.section-link {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-accent);
}

.section-link:hover {
  text-decoration: underline;
}

/* --- Post Grid --- */
.post-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--space-lg);
}

/* --- Post Card --- */
.post-card {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
  border: 1px solid var(--color-border);
}

.post-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.post-card__image {
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: linear-gradient(135deg, var(--color-accent-soft), var(--color-tech-soft));
}

.post-card--research .post-card__image {
  background: linear-gradient(135deg, var(--color-research-soft), var(--color-accent-soft));
}

.post-card--tech .post-card__image {
  background: linear-gradient(135deg, var(--color-tech-soft), var(--color-accent-soft));
}

.post-card--trip .post-card__image {
  background: linear-gradient(135deg, var(--color-trip-soft), var(--color-tech-soft));
}

.post-card--food .post-card__image {
  background: linear-gradient(135deg, var(--color-food-soft), var(--color-accent-soft));
}

.post-card__image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.4s ease;
}

.post-card:hover .post-card__image img {
  transform: scale(1.04);
}

.post-card__content {
  padding: 1.25rem 1.4rem 1.5rem;
}

.post-card__date {
  font-size: 0.78rem;
  color: var(--color-text-muted);
  font-weight: 500;
  letter-spacing: 0.02em;
}

.post-card__title {
  font-family: var(--font-display);
  font-size: 1.2rem;
  line-height: 1.35;
  margin: 0.5rem 0;
  letter-spacing: -0.01em;
}

.post-card__title a:hover {
  color: var(--color-accent);
}

.post-card__excerpt {
  font-size: 0.88rem;
  color: var(--color-text-muted);
  line-height: 1.6;
  margin-bottom: 0.75rem;
}

.post-card__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

/* --- Tags --- */
.tag {
  display: inline-block;
  font-size: 0.78rem;
  color: var(--color-text-muted);
  background: var(--color-bg);
  padding: 0.15rem 0.55rem;
  border-radius: 4px;
  font-weight: 500;
}

.tag--sm {
  font-size: 0.72rem;
  padding: 0.1rem 0.45rem;
}

/* --- Post Full (Single Post) --- */
.post-full {
  max-width: var(--content-width);
  margin: 0 auto;
}

.post-header {
  text-align: center;
  padding: var(--space-xl) 0 var(--space-lg);
}

.post-meta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-md);
  margin-bottom: var(--space-md);
  font-size: 0.85rem;
}

.post-category {
  font-weight: 600;
  padding: 0.2rem 0.75rem;
  border-radius: 20px;
  font-size: 0.8rem;
}

.post-category--research {
  color: var(--color-research);
  background: var(--color-research-soft);
}

.post-category--tech {
  color: var(--color-tech);
  background: var(--color-tech-soft);
}

.post-category--trip {
  color: var(--color-trip);
  background: var(--color-trip-soft);
}

.post-category--food {
  color: var(--color-food);
  background: var(--color-food-soft);
}

.post-meta time {
  color: var(--color-text-muted);
}

.post-title {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 0.5rem;
}

.post-subtitle {
  font-size: 1.1rem;
  color: var(--color-text-muted);
  margin-top: 0.5rem;
}

.post-tags {
  margin-top: var(--space-md);
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}

/* --- Post Hero Image --- */
.post-hero {
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin-bottom: var(--space-xl);
  box-shadow: var(--shadow-md);
}

.post-hero img {
  width: 100%;
  aspect-ratio: 2 / 1;
  object-fit: cover;
}

/* --- Post Content (Prose) --- */
.post-content {
  font-size: 1rem;
  line-height: 1.8;
}

.post-content h2 {
  font-family: var(--font-display);
  font-size: 1.6rem;
  margin-top: var(--space-xl);
  margin-bottom: var(--space-md);
  letter-spacing: -0.02em;
  padding-bottom: 0.4rem;
  border-bottom: 2px solid var(--color-accent-soft);
}

.post-content h3 {
  font-size: 1.2rem;
  font-weight: 600;
  margin-top: var(--space-lg);
  margin-bottom: var(--space-sm);
}

.post-content p {
  margin-bottom: var(--space-md);
}

.post-content ul, .post-content ol {
  margin-bottom: var(--space-md);
  padding-left: 1.5rem;
}

.post-content li {
  margin-bottom: 0.4rem;
}

.post-content blockquote {
  border-left: 3px solid var(--color-accent);
  padding: var(--space-md) var(--space-lg);
  margin: var(--space-lg) 0;
  background: var(--color-accent-soft);
  border-radius: 0 var(--radius) var(--radius) 0;
  font-style: italic;
  color: var(--color-text-muted);
}

.post-content code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: #e2e8f0;
  padding: 0.15em 0.4em;
  border-radius: 4px;
}

.post-content pre {
  background: var(--color-code-bg);
  color: #abb2bf;
  padding: 1.25rem 1.5rem;
  border-radius: var(--radius);
  overflow-x: auto;
  margin: var(--space-lg) 0;
  line-height: 1.5;
  box-shadow: var(--shadow-sm);
}

.post-content pre code {
  background: none;
  padding: 0;
  color: inherit;
  font-size: 0.85rem;
}

.post-content img {
  border-radius: var(--radius);
  margin: var(--space-lg) 0;
  box-shadow: var(--shadow-sm);
}

.post-content table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--space-lg) 0;
  font-size: 0.9rem;
}

.post-content th, .post-content td {
  padding: 0.6rem 1rem;
  border: 1px solid var(--color-border);
  text-align: left;
}

.post-content th {
  background: var(--color-bg);
  font-weight: 600;
}

/* --- Post Footer / Navigation --- */
.post-footer {
  margin-top: var(--space-2xl);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--color-border);
}

.post-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
}

.post-nav__prev, .post-nav__next {
  display: block;
  padding: var(--space-md);
  border-radius: var(--radius);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  transition: all 0.2s;
}

.post-nav__prev:hover, .post-nav__next:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-sm);
}

.post-nav__next {
  text-align: right;
}

.post-nav__label {
  display: block;
  font-size: 0.78rem;
  color: var(--color-text-muted);
  margin-bottom: 0.25rem;
}

.post-nav__title {
  font-weight: 600;
  font-size: 0.9rem;
}

/* --- Category Page --- */
.category-header {
  text-align: center;
  padding: var(--space-xl) 0;
}

.category-title {
  font-family: var(--font-display);
  font-size: 2.2rem;
  letter-spacing: -0.03em;
}

.category-desc {
  color: var(--color-text-muted);
  margin-top: 0.5rem;
  font-size: 1.05rem;
}

/* --- About Page --- */
.about-page {
  max-width: var(--content-width);
  margin: 0 auto;
}

.about-header {
  text-align: center;
  padding: var(--space-xl) 0;
}

.about-header h1 {
  font-family: var(--font-display);
  font-size: 2.2rem;
}

.about-content {
  font-size: 1rem;
  line-height: 1.8;
}

.about-content p {
  margin-bottom: var(--space-md);
}

.about-subtitle {
  color: var(--color-text-muted);
  font-size: 1.1rem;
  margin-top: 0.5rem;
}

/* Resume Grid */
.resume-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-lg);
  margin: var(--space-xl) 0;
}

@media (max-width: 768px) {
  .resume-grid {
    grid-template-columns: 1fr;
  }
}

.resume-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: var(--space-lg);
}

.resume-card--full {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: var(--space-lg);
  margin: var(--space-lg) 0;
}

.resume-card-title {
  font-family: var(--font-display);
  font-size: 1.2rem;
  margin-bottom: var(--space-md);
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--color-accent);
  display: inline-block;
}

.resume-item {
  margin-bottom: var(--space-md);
}

.resume-item:last-child {
  margin-bottom: 0;
}

.resume-item h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.2rem;
}

.resume-org {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  margin-bottom: 0.1rem !important;
}

.resume-date {
  color: var(--color-text-muted);
  font-size: 0.8rem;
  opacity: 0.7;
  margin-bottom: 0 !important;
}

/* Skill Tags */
.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.skill-tag {
  display: inline-block;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 6px;
  padding: 0.25rem 0.75rem;
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

/* Publications */
.pub-summary {
  margin-bottom: var(--space-md) !important;
  color: var(--color-text-muted);
}

.pub-item {
  padding-left: 2.5rem;
  border-left: 2px solid var(--color-border);
  margin-bottom: var(--space-md);
  position: relative;
}

.pub-num {
  position: absolute;
  left: -0.75rem;
  top: 0;
  width: 1.5rem;
  height: 1.5rem;
  background: var(--color-accent);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  font-weight: 600;
}

.pub-item:last-child {
  margin-bottom: 0;
}

.pub-title {
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: 0.2rem !important;
  line-height: 1.4;
}

.pub-authors {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 0.1rem !important;
}

.pub-journal {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  opacity: 0.7;
  margin-bottom: 0 !important;
}

/* --- Footer --- */
.site-footer {
  margin-top: var(--space-2xl);
  border-top: 1px solid var(--color-border);
  padding: var(--space-xl) 1.5rem;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  text-align: center;
}

.footer-brand {
  margin-bottom: var(--space-md);
}

.footer-brand .logo-icon {
  font-size: 1.6rem;
}

.footer-brand p {
  color: var(--color-text-muted);
  font-size: 0.88rem;
  margin-top: 0.5rem;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  margin-bottom: var(--space-md);
}

.footer-links a {
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--color-text-muted);
}

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

.footer-copy p {
  font-size: 0.78rem;
  color: var(--color-text-muted);
}

/* --- Responsive --- */
@media (max-width: 768px) {
  html { font-size: 16px; }

  .site-nav {
    display: none;
    position: fixed;
    top: 58px;
    left: 0;
    right: 0;
    background: var(--color-bg);
    flex-direction: column;
    padding: var(--space-md);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-md);
    z-index: 99;
  }

  .site-nav.is-open { display: flex; }

  .nav-toggle { display: flex; }

  .nav-toggle.is-active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }
  .nav-toggle.is-active span:nth-child(2) { opacity: 0; }
  .nav-toggle.is-active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
  }

  .post-grid {
    grid-template-columns: 1fr;
  }

  .post-nav {
    grid-template-columns: 1fr;
  }

  .hero { padding: var(--space-xl) 0 var(--space-lg); }
}

/* --- Animations --- */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

.hero { animation: fadeUp 0.6s ease-out; }
.post-card { animation: fadeUp 0.5s ease-out backwards; }
.post-card:nth-child(2) { animation-delay: 0.08s; }
.post-card:nth-child(3) { animation-delay: 0.16s; }
.post-card:nth-child(4) { animation-delay: 0.24s; }
.post-full { animation: fadeUp 0.5s ease-out; }