/* ============================================
   Modern Academic Portfolio - Main Stylesheet
   Orange/Amber Professional Theme
   ============================================ */

/* CSS Variables */
:root {
  --primary-color: #d97706;
  --primary-dark: #b45309;
  --primary-light: #f59e0b;
  --accent-color: #ea580c;
  --text-primary: #1f2937;
  --text-secondary: #4b5563;
  --text-muted: #6b7280;
  --bg-primary: #ffffff;
  --bg-secondary: #fffbeb;
  --bg-tertiary: #fef3c7;
  --border-color: #fde68a;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --transition: all 0.3s ease;
  --max-width: 1200px;
  --nav-height: 70px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', 'Source Sans Pro', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   Navigation
   ============================================ */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  transition: var(--transition);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: -0.02em;
}

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

.nav-menu {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  list-style: none;
}

.nav-link {
  padding: 0.5rem 1rem;
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

.nav-link:hover {
  color: var(--primary-color);
  background-color: var(--bg-tertiary);
}

.nav-link.active {
  color: var(--primary-color);
  background-color: rgba(217, 119, 6, 0.1);
}

/* Mobile Navigation Toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.hamburger {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--text-primary);
  position: relative;
  transition: var(--transition);
}

.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  width: 24px;
  height: 2px;
  background-color: var(--text-primary);
  transition: var(--transition);
}

.hamburger::before {
  top: -7px;
}

.hamburger::after {
  top: 7px;
}

.nav-toggle.active .hamburger {
  background-color: transparent;
}

.nav-toggle.active .hamburger::before {
  top: 0;
  transform: rotate(45deg);
}

.nav-toggle.active .hamburger::after {
  top: 0;
  transform: rotate(-45deg);
}

/* ============================================
   Main Content
   ============================================ */
.main-content {
  min-height: calc(100vh - var(--nav-height) - 100px);
  padding-top: var(--nav-height);
}

/* ============================================
   Page Header
   ============================================ */
.page-header {
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
  padding: 4rem 2rem 3rem;
  border-bottom: 1px solid var(--border-color);
}

.page-header-content {
  max-width: var(--max-width);
  margin: 0 auto;
}

.page-title {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
  letter-spacing: -0.03em;
}

.page-subtitle {
  font-size: 1.1rem;
  color: var(--text-muted);
  font-weight: 400;
}

/* ============================================
   Home Page - Hero Section (Bio + News)
   ============================================ */
.hero {
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
  padding: 3rem 2rem 1.5rem;
}

.hero-container {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 333px;
  gap: 2rem;
  align-items: start;
}

.hero-left {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 2.5rem;
  align-items: start;
}

.hero-image {
  position: sticky;
  top: calc(var(--nav-height) + 2rem);
}

.hero-avatar {
  width: 100%;
  max-width: 220px;
  aspect-ratio: 1;
  object-fit: cover;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  border: 4px solid var(--bg-primary);
}

.hero-content {
  padding-top: 0.25rem;
}

.hero-name {
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.4rem;
  letter-spacing: -0.03em;
}

.hero-title {
  font-size: 1.15rem;
  color: var(--primary-color);
  font-weight: 600;
  margin-bottom: 0.2rem;
}

.hero-affiliation {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.hero-affiliation a {
  color: var(--primary-color);
  text-decoration: none;
}

.hero-affiliation a:hover {
  text-decoration: underline;
}

.hero-social {
  display: flex;
  gap: 0.6rem;
  margin-bottom: 1.25rem;
}

.social-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background-color: var(--bg-tertiary);
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 1.1rem;
  transition: var(--transition);
  border: 1px solid var(--border-color);
}

.social-link:hover {
  background-color: var(--primary-color);
  color: white;
  border-color: var(--primary-color);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

/* Hero Right - News Sidebar */
.hero-right {
  position: sticky;
  top: calc(var(--nav-height) + 2rem);
}

.news-section {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1rem;
  box-shadow: var(--shadow-md);
}

.news-section .section-title {
  margin-bottom: 0.5rem;
  font-size: 1rem;
  padding-bottom: 0.35rem;
}

.news-list-scroll {
  max-height: 380px;
  overflow-y: auto;
  padding-right: 0.4rem;
}

.news-list-scroll::-webkit-scrollbar {
  width: 5px;
}

.news-list-scroll::-webkit-scrollbar-track {
  background: var(--bg-tertiary);
  border-radius: 3px;
}

.news-list-scroll::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: 3px;
}

.news-list-scroll::-webkit-scrollbar-thumb:hover {
  background: var(--primary-light);
}

.news-item {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border-color);
}

.news-item:first-child {
  padding-top: 0;
}

.news-item:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.news-date {
  font-size: 0.65rem;
  font-weight: 600;
  color: var(--primary-color);
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.news-content {
  color: var(--text-secondary);
  font-size: 0.8rem;
  line-height: 1.4;
}

.news-content a {
  color: var(--primary-color);
  text-decoration: none;
}

.news-content a:hover {
  text-decoration: underline;
}

/* ============================================
   About Section
   ============================================ */
.about-text {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.about-text p {
  margin-bottom: 0.75rem;
}

.about-text p:last-child {
  margin-bottom: 0;
}

.about-text a {
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 500;
}

.about-text a:hover {
  text-decoration: underline;
}

/* ============================================
   Home Main Content
   ============================================ */
.home-main {
  padding: 1.5rem 2rem 3rem;
  background-color: var(--bg-primary);
}

.home-main-container {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
}

.content-section {
  margin-bottom: 0;
}

.content-section:last-child {
  grid-column: 1 / -1;
}

/* ============================================
   Sections
   ============================================ */
.section-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1.25rem;
  padding-bottom: 0.5rem;
  border-bottom: 3px solid var(--primary-color);
  display: inline-block;
  letter-spacing: -0.02em;
}

/* ============================================
   Experience & Education Cards
   ============================================ */
.exp-edu-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.exp-edu-card {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  transition: var(--transition);
  box-shadow: var(--shadow-sm);
}

.exp-edu-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--primary-light);
  transform: translateY(-1px);
}

.exp-edu-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 0.75rem;
  margin-bottom: 0.35rem;
  flex-wrap: wrap;
}

.exp-edu-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 0;
}

.exp-edu-date {
  font-size: 0.75rem;
  font-weight: 600;
  color: white;
  background-color: var(--primary-color);
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-sm);
  white-space: nowrap;
}

.exp-edu-org {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.exp-edu-org a {
  color: var(--primary-color);
  text-decoration: none;
}

.exp-edu-org a:hover {
  text-decoration: underline;
}

.exp-edu-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.55;
  margin: 0;
}

/* ============================================
   Research Interests
   ============================================ */
.interests-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}

.interest-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  transition: var(--transition);
}

.interest-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--primary-light);
}

.interest-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--primary-dark);
  margin-bottom: 0.4rem;
}

.interest-desc {
  color: var(--text-secondary);
  font-size: 0.875rem;
  line-height: 1.5;
}

/* ============================================
   Publications & Projects Cards
   ============================================ */
.cards-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2rem;
}

.cards-grid {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.card {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 1.5rem;
  background: var(--bg-primary);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-color);
  transition: var(--transition);
}

.card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
  border-color: var(--primary-light);
}

.card-image {
  width: 100%;
  height: 180px;
  object-fit: cover;
  background-color: var(--bg-tertiary);
}

.card-content {
  padding: 1.25rem 1.25rem 1.25rem 0;
  display: flex;
  flex-direction: column;
}

.card-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.4rem;
  line-height: 1.4;
}

.card-meta {
  font-size: 0.85rem;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
  font-weight: 500;
}

.card-authors {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 0.35rem;
}

.card-authors strong {
  color: var(--primary-dark);
}

.card-venue {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-style: italic;
  margin-bottom: 0.75rem;
}

.card-description {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.55;
  margin-bottom: 1rem;
  flex-grow: 1;
}

.card-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: auto;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.45rem 0.9rem;
  font-size: 0.8rem;
  font-weight: 600;
  text-decoration: none;
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

.btn-primary {
  background-color: var(--primary-color);
  color: white;
}

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

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

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

/* ============================================
   Footer
   ============================================ */
.footer {
  background-color: var(--text-primary);
  color: var(--bg-tertiary);
  padding: 2.5rem 2rem;
  text-align: center;
}

.footer-container {
  max-width: var(--max-width);
  margin: 0 auto;
}

.footer-social {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

.footer-social a {
  color: var(--bg-tertiary);
  font-size: 1.5rem;
  transition: var(--transition);
}

.footer-social a:hover {
  color: var(--primary-light);
  transform: translateY(-2px);
}

.footer-text {
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 1100px) {
  .hero-container {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .hero-right {
    position: static;
  }

  .news-list-scroll {
    max-height: 300px;
  }

  .home-main-container {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }

  .content-section:last-child {
    grid-column: 1;
  }

  .interests-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 768px) {
  :root {
    --nav-height: 60px;
  }

  .nav-toggle {
    display: block;
  }

  .nav-menu {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--bg-primary);
    flex-direction: column;
    padding: 1rem;
    gap: 0;
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
  }

  .nav-menu.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  .nav-link {
    padding: 1rem;
    width: 100%;
    text-align: center;
  }

  .hero {
    padding: 2rem 1.5rem;
    min-height: auto;
  }

  .hero-left {
    grid-template-columns: 1fr;
    gap: 1.5rem;
    text-align: center;
  }

  .hero-image {
    position: static;
    display: flex;
    justify-content: center;
  }

  .hero-avatar {
    max-width: 180px;
  }

  .hero-social {
    justify-content: center;
  }

  .hero-name {
    font-size: 1.85rem;
  }

  .home-main {
    padding: 2rem 1.5rem;
  }

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

  .exp-edu-header {
    flex-direction: column;
    gap: 0.35rem;
  }

  .exp-edu-date {
    align-self: flex-start;
  }

  .page-header {
    padding: 3rem 1.5rem 2rem;
  }

  .page-title {
    font-size: 2rem;
  }

  .cards-container {
    padding: 1.5rem;
  }

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

  .card-image {
    height: 200px;
  }

  .card-content {
    padding: 1.25rem;
  }
}

@media (max-width: 480px) {
  .hero-name {
    font-size: 1.6rem;
  }

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

  .card-title {
    font-size: 1rem;
  }

  .btn {
    padding: 0.4rem 0.75rem;
    font-size: 0.75rem;
  }

  .exp-edu-card {
    padding: 1rem;
  }

  .exp-edu-title {
    font-size: 0.95rem;
  }
}