/* Mobile Navigation Toggle Button */
.mobile-nav-toggle {
  display: none;
  position: fixed;
  top: 1.5rem;
  left: 1.5rem;
  z-index: 2001;
  width: 45px;
  height: 45px;
  border: none;
  background-color: #fff;
  cursor: pointer;
  border-radius: 50%;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  align-items: center;
  justify-content: center;
  padding: 0;
  transition: all 0.3s ease;
}

.mobile-nav-toggle i {
  font-size: 24px;
  color: var(--primary-color);
  line-height: 0;
}

/* Simple Hamburger Icon (CSS-only) */
.hamburger-icon {
  width: 24px;
  height: 18px;
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.hamburger-icon span {
  display: block;
  width: 100%;
  height: 2px;
  background-color: var(--primary-color);
  border-radius: 2px;
  transition: all 0.3s ease;
}

/* Transform to X when active */
.mobile-nav-toggle.active .hamburger-icon span:nth-child(1) {
  transform: translateY(8px) rotate(45deg);
}

.mobile-nav-toggle.active .hamburger-icon span:nth-child(2) {
  opacity: 0;
}

.mobile-nav-toggle.active .hamburger-icon span:nth-child(3) {
  transform: translateY(-8px) rotate(-45deg);
}

/* Overlay Backdrop */
.mobile-nav-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  z-index: 900;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  backdrop-filter: blur(2px);
}

.mobile-nav-overlay.active {
  opacity: 1;
  visibility: visible;
}

/* Responsive Design (Mobile) */
@media (max-width: 1024px) {
  /* Sidebar Behavior - 높은 특이성으로 !important 없이 오버라이드 */
  body .sidebar {
    width: 280px;
    height: 100vh;
    position: fixed;
    left: -280px;
    top: 0;
    border-right: 1px solid #e5e7eb;
    border-bottom: none;
    transition: left 0.3s ease-in-out;
    box-shadow: 4px 0 15px rgba(0, 0, 0, 0.1);
    z-index: 1001;
  }

  body .sidebar.active {
    left: 0;
  }

  /* Main Content Adjustments */
  .main-content {
    margin-left: 0;
    width: 100%;
  }

  .main-content > .container {
    padding: 4rem 2rem;
    /* Reduce padding side */
  }

  /* Challenge Item Stacking */
  .challenge-item {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .challenge-item.reverse {
    direction: ltr;
    /* Reset direction for vertical stacking */
  }

  .challenge-media {
    order: -1;
    /* Image always on top on mobile */
  }

  /* Section Padding Reduction - 높은 특이성으로 오버라이드 */
  .main-content .intro-section {
    padding: 4rem 2rem;
  }

  .main-content .section {
    padding: 0 2rem 4rem;
  }

  /* Show Mobile Toggle */
  .mobile-nav-toggle {
    display: flex;
  }
}

@media (max-width: 768px) {
  /* Typography Scaling - 특이성 증가로 !important 제거 */
  body h1 {
    font-size: 2rem;
  }

  body h2,
  body .section-title {
    font-size: 1.75rem;
  }

  body h3 {
    font-size: 1.25rem;
  }

  .sidebar .sidebar-logo h1 {
    font-size: 2.2rem;
  }

  .main-content .intro-section h2 {
    font-size: 1.75rem;
    margin-bottom: 2rem;
  }

  body .row {
    flex-direction: column;
    gap: 2rem;
  }

  .col-image {
    margin-top: 1rem;
  }

  /* Footer Centering */
  .sidebar-footer {
    text-align: center;
  }

  /* Stats grid responsive */
  .key-metrics-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }
}

/* 모바일 key-metrics */
@media (max-width: 480px) {
  .key-metrics-grid {
    grid-template-columns: 1fr 1fr;
    gap: 0.8rem;
    padding: 1.5rem 0;
  }

  .key-metrics-grid p {
    font-size: 1.6rem;
  }
}

/* 초소형 모바일 (480px 이하) */
@media (max-width: 480px) {
  /* 더 작은 타이포그래피 */
  body h1 {
    font-size: 1.75rem;
  }

  body h2,
  body .section-title {
    font-size: 1.5rem;
  }

  body h3 {
    font-size: 1.1rem;
  }

  /* 컨테이너 패딩 축소 */
  .main-content > .container {
    padding: 2rem 1rem;
  }

  .main-content .intro-section {
    padding: 2rem 1rem;
  }

  .main-content .section {
    padding: 0 1rem 2rem;
  }

  /* 사이드바 조정 */
  body .sidebar {
    width: 260px;
    padding: 1.5rem 1rem;
  }

  .sidebar-logo h1 {
    font-size: 1.75rem;
  }

  /* 카드 그리드 단일 컬럼 */
  .features-grid,
  .team-grid,
  #research-projects-container {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

  /* 이미지 높이 축소 */
  .features-grid .feature-card img {
    height: 250px;
  }

  /* 통계 뱃지 작게 */
  .stat-badge {
    padding: 0.4rem 0.8rem;
    font-size: 0.8rem;
  }

  /* 발행물 리스트 조정 */
  .iso-item {
    font-size: 0.9rem;
    padding-left: 1rem;
    text-indent: -1rem;
  }
}

/* Mobile Header - Logo bar for mobile view */
.mobile-header {
  display: none;
}

@media (max-width: 1024px) {
  .mobile-header {
    display: flex;
    align-items: center;
    justify-content: center;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 60px;
    background-color: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(10px);
    z-index: 1000;
    /* Ensure visibility */
    /* border-bottom removed */
    /* No padding-right to ensure center alignment */
    flex-direction: column;
    padding: 1rem 0;
    height: auto;
    min-height: 120px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
    /* Subtle shadow for depth */
  }

  /* Move toggle button position slightly to align with header if needed, but current top: 1.5rem is ~24px */

  .mobile-header .mobile-logo {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-decoration: none;
    text-align: center;
  }

  .mobile-header .mobile-logo h1 {
    font-family: var(--logo-font);
    font-weight: 800;
    font-size: 2.2rem;
    /* Increased size for impact */
    color: #003366;
    line-height: 1.1;
    letter-spacing: 0;
    font-kerning: normal;
    font-stretch: normal;
    font-feature-settings: "kern" 1, "liga" 1;
    text-rendering: geometricPrecision;
    margin: 0 0 0.5rem 0;
  }

  .mobile-header .mobile-logo .logo-subtitle {
    font-family: "Inter", sans-serif;
    font-size: 1rem;
    /* Increased readability */
    color: #64748b;
    font-weight: 700;
    line-height: 1.4;
  }

  /* Ensure breaks work */
  .mobile-header br {
    display: block;
  }

  /* Push main content down so it doesn't hide behind header */
  .main-content {
    padding-top: 140px;
  }

  /* Adjust intro section padding top since we added margin */
  .intro-section {
    padding-top: 2rem;
  }

  /* Challenges Page Responsive */
  .project-section {
    padding: 2rem;
  }

  .project-body .project-text > div {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .projects-images {
    flex-direction: column;
  }

  .project-images figure {
    width: 100%;
  }

  .mechanism-cards {
    grid-template-columns: 1fr;
  }
}

/* Mobile Language Toggle */
.mobile-lang-toggle {
  display: none;
}

@media (max-width: 1024px) {
  .mobile-lang-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 6px;
    background: rgba(255, 255, 255, 0.1);
    color: #fff;
    font-size: 0.75rem;
    font-weight: 700;
    text-decoration: none;
    letter-spacing: 0.05em;
    position: absolute;
    right: 60px;
    top: 50%;
    transform: translateY(-50%);
    transition: background 0.2s;
  }

  .mobile-lang-toggle:hover {
    background: rgba(255, 255, 255, 0.2);
  }
}