/* ==========================================================================
   DESIGN SYSTEM - Eghbal A. Hosseini Personal Website
   Modern, minimal, clean with dark/light theming
   ========================================================================== */

/* --------------------------------------------------------------------------
   CSS Custom Properties (Design Tokens)
   -------------------------------------------------------------------------- */
:root {
  /* Typography */
  --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Font sizes */
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Border radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 350ms ease;

  /* Container */
  --container-max: 900px;
  --container-padding: var(--space-6);

  /* Z-index */
  --z-nav: 100;
  --z-modal: 200;
}

/* Light theme (default) */
:root,
[data-theme="light"] {
  --color-bg: #fafafa;
  --color-bg-secondary: #ffffff;
  --color-bg-tertiary: #f4f4f5;
  --color-text: #18181b;
  --color-text-secondary: #52525b;
  --color-text-muted: #71717a;
  --color-border: #e4e4e7;
  --color-border-light: #f4f4f5;
  --color-accent: #7c2d2d;
  --color-accent-hover: #991b1b;
  --color-accent-light: rgba(124, 45, 45, 0.1);
  --color-link: #2563eb;
  --color-link-hover: #1d4ed8;
  --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 -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
}

/* Dark theme */
[data-theme="dark"] {
  --color-bg: #0a0a0a;
  --color-bg-secondary: #18181b;
  --color-bg-tertiary: #27272a;
  --color-text: #fafafa;
  --color-text-secondary: #a1a1aa;
  --color-text-muted: #71717a;
  --color-border: #27272a;
  --color-border-light: #3f3f46;
  --color-accent: #f87171;
  --color-accent-hover: #fca5a5;
  --color-accent-light: rgba(248, 113, 113, 0.1);
  --color-link: #60a5fa;
  --color-link-hover: #93c5fd;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -4px rgba(0, 0, 0, 0.3);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

body {
  font-family: var(--font-primary);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  transition: background-color var(--transition-base), color var(--transition-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* --------------------------------------------------------------------------
   Typography
   -------------------------------------------------------------------------- */
h1,
h2,
h3,
h4,
h5,
h6 {
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-text);
}

h1 {
  font-size: var(--text-4xl);
  font-weight: 700;
}

h2 {
  font-size: var(--text-2xl);
  margin-bottom: var(--space-4);
}

h3 {
  font-size: var(--text-xl);
}

h4 {
  font-size: var(--text-lg);
}

p {
  margin-bottom: var(--space-4);
  color: var(--color-text-secondary);
}

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

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

strong {
  font-weight: 600;
  color: var(--color-text);
}

/* --------------------------------------------------------------------------
   Layout & Container
   -------------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

.section {
  padding: var(--space-16) 0;
}

.section-title {
  font-size: var(--text-xl);
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: var(--space-8);
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.section-title::before {
  content: '';
  display: block;
  width: 3px;
  height: 1.2em;
  background: var(--color-accent);
  border-radius: var(--radius-full);
}

/* --------------------------------------------------------------------------
   Navigation
   -------------------------------------------------------------------------- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-nav);
  background: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: background-color var(--transition-base), border-color var(--transition-base);
}

.nav-content {
  display: flex;
  align-items: center;
  gap: var(--space-8);
  height: 64px;
}

.nav-actions {
  margin-left: auto;
}

.nav-brand {
  font-weight: 700;
  font-size: var(--text-xl);
  color: var(--color-accent);
  text-decoration: none;
  letter-spacing: -0.01em;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  list-style: none;
}

.nav-link {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  text-decoration: none;
  padding: var(--space-2) 0;
  position: relative;
  transition: color var(--transition-fast);
}

.nav-link::after {
  content: '';
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: var(--color-accent);
  transform: scaleX(0);
  transition: transform var(--transition-fast);
}

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

.nav-link:hover::after,
.nav-link.active::after {
  transform: scaleX(1);
}

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

/* Theme toggle */
.theme-toggle {
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-2);
  cursor: pointer;
  color: var(--color-text);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  background: var(--color-bg-tertiary);
  border-color: var(--color-border-light);
}

.theme-toggle svg {
  width: 20px;
  height: 20px;
}

.theme-toggle .sun {
  display: none;
}

.theme-toggle .moon {
  display: block;
}

[data-theme="dark"] .theme-toggle .sun {
  display: block;
}

[data-theme="dark"] .theme-toggle .moon {
  display: none;
}

/* Mobile nav toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  padding: var(--space-2);
  cursor: pointer;
  color: var(--color-text);
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: currentColor;
  margin: 5px 0;
  transition: all var(--transition-fast);
}

/* Mobile responsive nav */
@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-bg-secondary);
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    padding: var(--space-4);
    gap: var(--space-2);
  }

  .nav-links.active {
    display: flex;
  }

  .nav-link {
    padding: var(--space-3) var(--space-4);
    width: 100%;
  }

  .nav-toggle {
    display: block;
  }

  .nav-actions {
    display: flex;
    gap: var(--space-3);
  }
}

/* Spacer for fixed nav */
.nav-spacer {
  height: 64px;
}

/* --------------------------------------------------------------------------
   Hero Section
   -------------------------------------------------------------------------- */
.hero {
  padding: var(--space-16) 0 var(--space-12);
}

.hero-content {
  display: flex;
  flex-direction: row;
  gap: var(--space-10);
  align-items: flex-start;
}

.hero-image {
  flex-shrink: 0;
}

.hero-image img {
  width: 165px;
  height: 165px;
  border-radius: var(--radius-lg);
  object-fit: cover;
  border: 3px solid var(--color-border);
  transition: border-color var(--transition-base);
}

.hero-text {
  flex: 1;
}

.hero-name {
  font-size: var(--text-3xl);
  font-weight: 700;
  color: var(--color-accent);
  margin-bottom: var(--space-2);
}

.hero-title {
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
  font-weight: 400;
}

.hero-bio {
  font-size: var(--text-base);
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-6);
}

.hero-bio a {
  font-weight: 500;
}

/* Social icons */
.social-links {
  display: flex;
  gap: var(--space-3);
  flex-wrap: wrap;
}

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

.social-link:hover {
  background: var(--color-accent);
  color: white;
  transform: translateY(-2px);
}

.social-link svg {
  width: 20px;
  height: 20px;
}

/* Mobile hero */
@media (max-width: 600px) {
  .hero-content {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }

  .hero-name {
    font-size: var(--text-2xl);
  }

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

/* --------------------------------------------------------------------------
   Research Interests (inside hero)
   -------------------------------------------------------------------------- */
.research-interests {
  margin-top: var(--space-4);
  margin-bottom: var(--space-6);
}

.research-interests-title {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: var(--space-3);
}

.theme-pills {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}

.theme-pill {
  background: var(--color-bg-tertiary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  padding: var(--space-1) var(--space-4);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.theme-pill:hover {
  border-color: var(--color-accent);
  color: var(--color-text);
}

.theme-pill.active {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: white;
}

.theme-desc {
  font-size: var(--text-base);
  color: var(--color-text-secondary);
  line-height: 1.7;
  min-height: 3.4em;
  position: relative;
}

.theme-desc-text {
  animation: fadeInDesc 0.3s ease;
}

@keyframes fadeInDesc {
  from {
    opacity: 0;
    transform: translateY(4px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Inline citation references */
.cite-ref {
  display: inline;
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-accent);
  cursor: pointer;
  position: relative;
  transition: color var(--transition-fast);
  text-decoration: none;
  border-bottom: 1px dashed var(--color-accent);
  padding-bottom: 1px;
}

.cite-ref:hover {
  color: var(--color-accent-hover);
}

/* Citation tooltip */
.cite-tooltip {
  position: fixed;
  z-index: var(--z-modal);
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
  max-width: 380px;
  min-width: 260px;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
  transform: translateY(6px);
}

.cite-tooltip.visible {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

.cite-tooltip-title {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.4;
  margin-bottom: var(--space-2);
}

.cite-tooltip-authors {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  line-height: 1.5;
  margin-bottom: var(--space-1);
}

.cite-tooltip-venue {
  font-size: var(--text-xs);
  color: var(--color-accent);
  font-weight: 500;
  margin-bottom: var(--space-3);
}

.cite-tooltip-link {
  display: inline-block;
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-link);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.cite-tooltip-link:hover {
  color: var(--color-link-hover);
}

/* --------------------------------------------------------------------------
   Updates Section
   -------------------------------------------------------------------------- */
.updates-list {
  list-style: none;
}

.update-item {
  display: flex;
  gap: var(--space-4);
  padding: var(--space-4) 0;
  border-bottom: 1px solid var(--color-border);
}

.update-item:last-child {
  border-bottom: none;
}

.update-date {
  flex-shrink: 0;
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-accent);
  width: 100px;
}

.update-content {
  font-size: var(--text-base);
  color: var(--color-text-secondary);
}

.update-content a {
  font-weight: 500;
}

@media (max-width: 600px) {
  .update-item {
    flex-direction: column;
    gap: var(--space-1);
  }
}

/* --------------------------------------------------------------------------
   Publications Section
   -------------------------------------------------------------------------- */
.filter-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-6);
}

.filter-btn {
  background: var(--color-bg-tertiary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.filter-btn:hover,
.filter-btn.active {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: white;
}

.publications-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.pub-card {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all var(--transition-base);
}

.pub-card:hover {
  border-color: var(--color-accent-light);
  box-shadow: var(--shadow-sm);
}

.pub-card.hidden {
  display: none;
}

.pub-header {
  padding: var(--space-5);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--space-4);
}

.pub-header:hover {
  background: var(--color-bg-tertiary);
}

.pub-info {
  flex: 1;
}

.pub-number {
  display: inline-block;
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-accent);
  margin-right: var(--space-2);
}

.pub-title {
  font-size: var(--text-base);
  font-weight: 500;
  color: var(--color-text);
  line-height: 1.5;
  margin-bottom: var(--space-2);
}

.pub-venue {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}

.pub-authors {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-top: var(--space-1);
  line-height: 1.5;
}

.pub-author-highlight {
  font-weight: 600;
  color: var(--color-accent);
}

.pub-toggle {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-bg-tertiary);
  border-radius: var(--radius-full);
  color: var(--color-text-secondary);
  transition: transform var(--transition-fast);
}

.pub-card.expanded .pub-toggle {
  transform: rotate(180deg);
}

.pub-details {
  display: none;
  padding: 0 var(--space-5) var(--space-5);
  border-top: 1px solid var(--color-border);
}

.pub-card.expanded .pub-details {
  display: block;
}

.pub-abstract {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-4);
  padding-top: var(--space-4);
}

.pub-abstract strong {
  color: var(--color-text);
  display: block;
  margin-bottom: var(--space-2);
}

.pub-figure {
  margin-bottom: var(--space-4);
  background: var(--color-bg-tertiary);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  text-align: center;
  color: var(--color-text-muted);
  font-size: var(--text-sm);
}

/* Hide figure placeholder when no image is present */
.pub-figure:not(:has(img)) {
  display: none;
}

.pub-figure img {
  max-width: 100%;
  border-radius: var(--radius-md);
}

.pub-links {
  display: flex;
  gap: var(--space-3);
  flex-wrap: wrap;
}

.pub-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  padding: var(--space-2) var(--space-3);
  background: var(--color-bg-tertiary);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: all var(--transition-fast);
}

.pub-link:hover {
  background: var(--color-accent);
  color: white;
}

.pub-link svg {
  width: 16px;
  height: 16px;
}

/* --------------------------------------------------------------------------
   CV Section
   -------------------------------------------------------------------------- */
.cv-viewer {
  margin-top: var(--space-2);
}

.cv-actions {
  display: flex;
  justify-content: flex-end;
  margin-bottom: var(--space-4);
}

.cv-download-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-secondary);
  background: var(--color-bg-tertiary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: all var(--transition-fast);
  cursor: pointer;
}

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

.cv-download-btn svg {
  width: 16px;
  height: 16px;
}

.cv-iframe {
  width: 100%;
  min-height: 80vh;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-bg-secondary);
}

@media (max-width: 600px) {
  .cv-iframe {
    min-height: 60vh;
  }
}

/* --------------------------------------------------------------------------
   Animations & Utilities
   -------------------------------------------------------------------------- */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger animation delays */
.stagger-1 {
  transition-delay: 0.1s;
}

.stagger-2 {
  transition-delay: 0.2s;
}

.stagger-3 {
  transition-delay: 0.3s;
}

.stagger-4 {
  transition-delay: 0.4s;
}

/* Screen reader only */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.footer {
  padding: var(--space-8) 0;
  border-top: 1px solid var(--color-border);
  text-align: center;
}

.footer p {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin: 0;
}