/* Academic Professional Website - Design System */

/* Design Tokens */
:root {
  /* Colors */
  --color-primary: #0E419C;
  --color-primary-dark: #0A2F70;
  --color-text: #000000;
  --color-text-secondary: #000000;
  --color-background: #ffffff;
  --color-border: rgba(14, 65, 156, 0.1);
  --color-border-light: rgba(14, 65, 156, 0.05);
  
  /* Typography Scale */
  --font-size-xs: 12px;
  --font-size-sm: 14px;
  --font-size-base: 15px;
  --font-size-lg: 18px;
  --font-size-xl: 24px;
  --font-size-xxl: 32px;
  
  /* Font Weights */
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  /* Line Heights */
  --line-height-tight: 1.2;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.6;
  
  /* Spacing Scale */
  --space-xs: 8px;
  --space-sm: 16px;
  --space-md: 24px;
  --space-lg: 32px;
  --space-xl: 48px;
  --space-xxl: 64px;
  
  /* Layout */
  --container-max-width: 1200px;
  --border-radius: 8px;
  --transition: all 0.2s ease;
  --transition-smooth: all 0.3s ease;
}

/* Base Styles */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: 0;
  min-height: 100vh;
  background: var(--color-background);
  font-family: 'Roboto', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-relaxed);
  color: var(--color-text);
  letter-spacing: 0.01em;
  padding-top: var(--space-lg);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: 'Roboto', sans-serif;
  color: var(--color-primary);
  margin: 0 0 var(--space-sm) 0;
  font-weight: var(--font-weight-semibold);
  line-height: var(--line-height-tight);
  letter-spacing: -0.01em;
}

h1 {
  font-weight: var(--font-weight-bold);
  font-size: var(--font-size-xxl);
  letter-spacing: -0.02em;
}

h2 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-sm);
}

h3 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-xs);
  text-decoration: none;
}


h4, h5, h6 {
  font-size: var(--font-size-base);
  margin-bottom: var(--space-xs);
}

p {
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-normal);
  margin: 0 0 var(--space-xs) 0;
  color: var(--color-text);
}

/* Links */
a {
  color: var(--color-primary);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: var(--color-primary);
}

.main-content a {
  color: var(--color-primary);
  text-decoration: none;
  transition: var(--transition);
  position: relative;
}

.main-content a::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 50%;
  width: 0;
  height: 1px;
  background: rgba(14, 65, 156, 0.6);
  transition: var(--transition-smooth);
  transform: translateX(-50%);
}

.main-content a:hover {
  color: var(--color-primary);
}

.main-content a:hover::after {
  width: 100%;
}

/* Layout */
.main-content {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: var(--space-sm) var(--space-sm) var(--space-xxl) var(--space-sm);
  min-height: calc(100vh - 140px);
}

/* Navigation */
.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: transparent;
  padding: 1px var(--space-md);
  margin-bottom: var(--space-lg);
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  width: 100%;
  z-index: 9999;
  will-change: background, backdrop-filter;
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.navbar-logo {
  height: 28px;
  width: auto;
  object-fit: contain;
  transition: var(--transition);
  cursor: pointer;
}


.navbar-title {
  font-family: 'Noto Serif SC', 'Roboto', sans-serif;
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  color: var(--color-primary);
  letter-spacing: 0.5px;
  text-decoration: none;
  transition: var(--transition-smooth);
  position: relative;
  padding: 4px var(--space-xs);
}

.navbar-title:hover {
  color: var(--color-primary);
}

.navbar-nav {
  display: flex;
  align-items: center;
  font-size: var(--font-size-base);
  position: relative;
}

.nav-link {
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-semibold);
  color: var(--color-primary);
  text-decoration: none;
  margin: 0 3px;
  padding: var(--space-xs) 12px;
  border-radius: 4px;
  transition: var(--transition-smooth);
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 50%;
  width: 0;
  height: 1px;
  background: rgba(14, 65, 156, 0.6);
  transition: var(--transition-smooth);
  transform: translateX(-50%);
}

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

.nav-link:hover::after {
  width: 100%;
}

.nav-link.active {
  color: var(--color-primary);
  font-weight: var(--font-weight-bold);
}

.nav-link.active::after {
  width: 100%;
  height: 1px;
  background: rgba(14, 65, 156, 0.8);
}


.nav-separator {
  color: var(--color-primary);
  font-weight: var(--font-weight-semibold);
  font-size: var(--font-size-base);
  margin: 0 4px;
}

/* Mobile Menu */
.mobile-menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  flex-direction: column;
  justify-content: space-around;
  width: var(--space-lg);
  height: var(--space-lg);
  padding: 6px;
  transition: var(--transition);
  border-radius: 4px;
  will-change: background;
}

.hamburger-line {
  width: 20px;
  height: 2px;
  background: var(--color-primary);
  transition: all 0.3s ease-in-out;
  transform-origin: center;
  border-radius: 1px;
  will-change: transform, opacity;
}

.mobile-menu-toggle.active .hamburger-line:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-toggle.active .hamburger-line:nth-child(2) {
  opacity: 0;
  transform: scale(0);
}

.mobile-menu-toggle.active .hamburger-line:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

.mobile-menu-toggle:hover {
  background: rgba(14, 65, 156, 0.05);
}

.mobile-menu-toggle:hover .hamburger-line {
  background: var(--color-primary-dark);
}

/* Profile Section */
.profile-section {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xxl);
  margin: var(--space-md) 0;
  padding: var(--space-md) var(--space-xxl);
  max-width: 1400px;
  margin-left: auto;
  margin-right: auto;
  min-height: 40vh;
}

.profile-photo-container {
  flex-shrink: 0;
}

.profile-photo {
  border-radius: 20px;
  width: 250px;
  height: auto;
  object-fit: cover;
  transition: var(--transition-smooth);
}


.profile-info {
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-align: left;
  flex: 1;
}

.profile-name {
  font-size: 44px;
  font-weight: var(--font-weight-bold);
  margin-bottom: var(--space-sm);
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--color-primary);
}

.profile-title {
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  margin-bottom: var(--space-xs);
  line-height: var(--line-height-normal);
  color: var(--color-text);
}

.profile-affiliation {
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  margin-bottom: var(--space-md);
  line-height: var(--line-height-normal);
  color: var(--color-text);
}

.profile-divider {
  border: none;
  border-top: 1px solid rgba(14, 65, 156, 0.2);
  margin: var(--space-sm) 0;
  width: 100%;
  margin-left: 0;
}

/* Profile Sections */
.profile-research,
.profile-contact {
  margin-bottom: var(--space-sm);
}

.research-heading,
.contact-heading {
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-semibold);
  color: var(--color-primary);
  margin: 0 0 var(--space-xs) 0;
  line-height: var(--line-height-normal);
}

.research-text,
.contact-text {
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-normal);
  color: var(--color-text);
  margin: 0;
}



.email-link {
  font-size: inherit;
  font-weight: inherit;
  color: var(--color-primary);
  text-decoration: none;
  transition: var(--transition);
  display: inline;
  position: relative;
}

.email-link::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 50%;
  width: 0;
  height: 1px;
  background: rgba(14, 65, 156, 0.6);
  transition: var(--transition-smooth);
  transform: translateX(-50%);
}

.email-link:hover {
  color: var(--color-primary);
}

.email-link:hover::after {
  width: 100%;
}


/* Paper System */
.paper-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  counter-reset: paper-counter;
}

.paper-card {
  padding: var(--space-xs) 0;
  margin-bottom: var(--space-xs);
  border-bottom: 1px solid var(--color-border);
  transition: var(--transition);
  position: relative;
  overflow: visible;
}

.paper-card:last-child {
  border-bottom: none;
}

.paper-title {
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  color: var(--color-primary);
  margin-bottom: var(--space-xs);
  line-height: 1.4;
  text-decoration: none !important;
}

.paper-title::before {
  counter-increment: paper-counter;
  content: counter(paper-counter) ". ";
  text-decoration: none !important;
  display: inline;
}

.paper-title span {
  text-decoration: none;
  position: relative;
}

.paper-title span::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 50%;
  width: 0;
  height: 1px;
  background: rgba(14, 65, 156, 0.6);
  transition: var(--transition-smooth);
  transform: translateX(-50%);
}

.paper-title:hover::after {
  width: 0 !important;
}

.paper-title span:hover::after {
  width: 100%;
}

.paper-metadata {
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-normal);
  margin: 0 0 var(--space-xs) 0;
  color: var(--color-text);
}


.paper-actions {
  display: flex;
  gap: var(--space-sm);
  margin: var(--space-xs) 0;
}

.abstract-btn {
  background: transparent;
  color: var(--color-primary);
  border: none;
  padding: 0;
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-normal);
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
  position: relative;
}

.abstract-btn::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 50%;
  width: 0;
  height: 1px;
  background: rgba(14, 65, 156, 0.6);
  transition: var(--transition-smooth);
  transform: translateX(-50%);
}

.abstract-btn:hover::after,
.abstract-btn:focus::after {
  width: 100%;
}

.abstract-btn:hover,
.abstract-btn:focus {
  color: var(--color-primary);
  outline: none;
}

.abstract-btn:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.paper-link {
  background: transparent;
  color: var(--color-primary);
  border: 1px solid var(--color-primary);
  padding: 6px var(--space-sm);
  border-radius: 4px;
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  text-decoration: none;
  transition: var(--transition);
  display: inline-block;
}

.paper-link:hover,
.paper-link:focus {
  background: rgba(14, 65, 156, 0.1);
  color: var(--color-primary);
  text-decoration: none;
}

.paper-link:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.abstract-popup {
  margin-top: var(--space-xs);
  padding: var(--space-sm);
  background: rgba(14, 65, 156, 0.02);
  border-left: 3px solid var(--color-primary);
  border-radius: 0 4px 4px 0;
  animation: slideDown 0.3s ease-out;
  will-change: transform, opacity;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.paper-abstract {
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-relaxed);
  margin: 0;
  color: var(--color-text);
  font-style: italic;
}

/* Error Pages */
.error-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  min-height: 70vh;
  padding: var(--space-xl) var(--space-lg);
  max-width: 800px;
  margin: 0 auto;
}

.error-code {
  font-size: 96px;
  font-weight: var(--font-weight-bold);
  color: var(--color-primary);
  margin-bottom: var(--space-lg);
  line-height: 1;
  letter-spacing: -0.02em;
}

.error-title {
  font-size: 36px;
  font-weight: var(--font-weight-semibold);
  margin-bottom: var(--space-lg);
  line-height: var(--line-height-tight);
  color: var(--color-primary);
  letter-spacing: -0.01em;
}

.error-description {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-normal);
  margin-bottom: var(--space-xl);
  line-height: var(--line-height-relaxed);
  max-width: 600px;
  color: var(--color-text);
  opacity: 0.9;
}

.error-actions {
  display: flex;
  gap: var(--space-md);
  justify-content: center;
  flex-wrap: wrap;
  margin-top: var(--space-lg);
}

.btn-primary {
  display: inline-block;
  padding: var(--space-sm) var(--space-xl);
  background: transparent;
  color: var(--color-primary);
  text-decoration: none !important;
  border-radius: 6px;
  font-weight: var(--font-weight-semibold);
  font-size: var(--font-size-base);
  transition: var(--transition);
  border: 2px solid var(--color-primary);
  text-align: center;
  min-width: 160px;
}

.btn-primary:hover {
  background: rgba(14, 65, 156, 0.1);
  border-color: var(--color-primary);
  color: var(--color-primary);
  text-decoration: none !important;
}

.btn-secondary {
  display: inline-block;
  padding: var(--space-sm) var(--space-xl);
  background: transparent;
  color: var(--color-primary);
  text-decoration: none !important;
  border: 2px solid var(--color-primary);
  border-radius: 6px;
  font-weight: var(--font-weight-medium);
  font-size: var(--font-size-base);
  transition: var(--transition);
  text-align: center;
  min-width: 160px;
}

.btn-secondary:hover {
  background: rgba(14, 65, 156, 0.1);
  color: var(--color-primary);
  border-color: var(--color-primary);
  text-decoration: none !important;
}

/* Responsive Design - Mobile First */
@media (max-width: 991px) {
  body {
    padding-top: var(--space-lg);
  }
  
  .navbar {
    padding: 1px var(--space-sm);
  }
  
  .navbar-brand {
    gap: var(--space-sm);
  }
  
  .navbar-logo {
    height: 26px;
  }
  
  .navbar-title {
    font-size: var(--font-size-lg);
  }
  
  .navbar-nav {
    font-size: var(--font-size-base);
  }
  
  .nav-link {
    font-size: var(--font-size-sm);
    padding: 6px 10px;
    margin: 0 2px;
    min-height: 40px;
  }
  
  .nav-separator {
    margin: 0 2px;
    font-size: var(--font-size-sm);
  }
  
  .profile-section {
    flex-direction: column;
    align-items: center;
    gap: var(--space-lg);
    padding: var(--space-lg) var(--space-sm);
    margin: var(--space-md) var(--space-xs);
    text-align: center;
    min-height: 45vh;
  }
  
  .profile-info {
    padding-left: 0;
    border-left: none;
    border-top: none;
    padding-top: 20px;
    min-height: auto;
    text-align: center;
  }
  
  .profile-photo {
    width: 220px;
  }
  
  .profile-name {
    font-size: 38px;
    line-height: 1.2;
    margin-bottom: var(--space-sm);
  }
  
  
  .profile-title {
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    margin-bottom: var(--space-xs);
  }
  
  .profile-affiliation {
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    margin-bottom: var(--space-sm);
  }
  
  
  .main-content {
    padding: var(--space-xl) var(--space-sm) var(--space-sm) var(--space-sm);
  }
  
}

@media (max-width: 767px) {
  body {
    padding-top: var(--space-lg);
  }
  
  .navbar {
    padding: 1px var(--space-sm);
  }
  
  .navbar-brand {
    gap: var(--space-xs);
  }
  
  .navbar-logo {
    height: 20px;
  }
  
  .navbar-title {
    font-size: var(--font-size-base);
  }
  
  .navbar-nav {
    font-size: var(--font-size-sm);
  }
  
  .mobile-menu-toggle {
    display: flex;
  }
  
  .nav-links {
    display: none;
    position: absolute;
    top: calc(100% + var(--space-xs));
    right: 0;
    background: rgba(255,255,255,0.98);
    border-radius: var(--space-xs);
    padding: var(--space-xs) 6px;
    flex-direction: column;
    align-items: stretch;
    z-index: 1000;
    opacity: 0;
    transition: var(--transition);
  }
  
  .nav-links.active {
    display: flex;
    opacity: 1;
  }
  
  .nav-links a {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    padding: var(--space-xs) var(--space-sm);
    margin: 2px 5px;
    border-radius: var(--space-xs);
    height: 36px;
    min-width: 100px;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    transition: var(--transition);
  }
  
  .nav-links a:hover {
    background: rgba(255,255,255,0.2);
  }
  
  .nav-separator {
    display: none;
  }
  
  .profile-section {
    gap: var(--space-md);
    padding: var(--space-sm) var(--space-sm);
    margin: var(--space-sm) var(--space-xs);
    min-height: 40vh;
  }
  
  .profile-photo {
    width: 170px;
  }
  
  .profile-name {
    font-size: var(--font-size-xxl);
    margin-bottom: var(--space-xs);
  }
  
  .profile-title {
    font-size: var(--font-size-base);
    margin-bottom: var(--space-xs);
    line-height: var(--line-height-normal);
  }
  
  .profile-affiliation {
    font-size: var(--font-size-base);
    margin-bottom: var(--space-lg);
    line-height: var(--line-height-normal);
  }
  
  
  
  
  
  
  
  .main-content {
    padding: var(--space-xl) var(--space-sm) var(--space-sm) var(--space-sm);
  }
  
}

@media (max-width: 575px) {
  body {
    padding-top: var(--space-lg);
  }
  
  .navbar {
    padding: 1px var(--space-xs);
  }
  
  .navbar-brand {
    gap: var(--space-xs);
  }
  
  .navbar-logo {
    height: 22px;
  }
  
  .navbar-title {
    font-size: var(--font-size-sm);
  }
  
  .nav-links {
    border-radius: var(--space-xs);
    padding: var(--space-xs) 4px;
  }
  
  .nav-links a {
    font-size: var(--font-size-sm);
    padding: var(--space-xs) var(--space-xs);
    margin: 1px 4px;
    border-radius: var(--space-xs);
    height: var(--space-lg);
    min-width: 85px;
  }
  
  .nav-links a:hover {
  }
  
  .profile-section {
    padding: var(--space-xs) var(--space-xs);
    margin: var(--space-xs) var(--space-xs);
    gap: var(--space-sm);
    min-height: 35vh;
  }
  
  .profile-name {
    font-size: var(--font-size-xl);
    margin-bottom: var(--space-xs);
  }
  
  .profile-title {
    font-size: var(--font-size-base);
    margin-bottom: var(--space-xs);
    line-height: var(--line-height-normal);
  }
  
  .profile-affiliation {
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
  }
  
  .profile-photo {
    width: 150px;
  }
  
  
  
  
  
  
  .main-content {
    padding: var(--space-xl) var(--space-xs) var(--space-xs) var(--space-xs);
  }
  
}

@media (max-width: 400px) {
  body {
    padding-top: var(--space-lg);
  }
  
  .navbar {
    padding: 1px var(--space-xs);
  }
  
  .navbar-brand {
    gap: var(--space-xs);
  }
  
  .navbar-logo {
    height: 18px;
  }
  
  .navbar-title {
    font-size: var(--font-size-xs);
  }
  
  .profile-section {
    padding: var(--space-xs) var(--space-xs);
    margin: var(--space-xs) var(--space-xs);
    gap: var(--space-sm);
    min-height: 30vh;
  }
  
  .profile-name {
    font-size: var(--font-size-xl);
  }
  
  .profile-title {
    font-size: var(--font-size-base);
    margin-bottom: var(--space-xs);
    line-height: var(--line-height-normal);
  }
  
  .profile-affiliation {
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
  }
  
  .profile-photo {
    width: 130px;
  }
  
  
  
  .research-text,
  .contact-text,
  
  .main-content {
    padding: var(--space-xl) var(--space-xs) var(--space-xs) var(--space-xs);
  }
  
  
  
  .error-section {
    padding: var(--space-lg) var(--space-sm);
    min-height: 60vh;
  }
  
  .error-code {
    font-size: 44px;
    margin-bottom: var(--space-md);
  }
  
  .error-title {
    font-size: var(--font-size-xl);
    margin-bottom: var(--space-md);
  }
  
  .error-description {
    font-size: var(--font-size-base);
    margin-bottom: var(--space-lg);
    max-width: none;
  }
  
  .error-actions {
    gap: var(--space-sm);
    flex-direction: column;
    align-items: center;
  }
  
  .btn-primary, .btn-secondary {
    padding: var(--space-sm) var(--space-lg);
    font-size: var(--font-size-base);
    min-width: 150px;
    margin: var(--space-xs) 0;
  }
}

/* Touch Device Optimizations */
@media (hover: none) and (pointer: coarse) {
  .nav-link {
    min-height: 44px;
    min-width: 44px;
  }
}

/* Calendar Section */
.calendar-container {
  margin-top: var(--space-sm);
  background: var(--color-background);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  overflow: hidden;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.calendar-container iframe {
  display: block;
  width: 100%;
  min-height: 600px;
  border: none;
}

/* Responsive Calendar */
@media (max-width: 768px) {
  .calendar-container iframe {
    min-height: 500px;
  }
}

@media (max-width: 600px) {
  .calendar-container iframe {
    min-height: 450px;
  }
}

@media (max-width: 400px) {
  .calendar-container iframe {
    min-height: 400px;
  }
}

/* Print Styles */
@media print {
  .navbar {
    display: none;
  }
  
  body {
    padding-top: 0;
  }
  
  .calendar-container {
    display: none;
  }
}