/*
 * Personal Academic Website Stylesheet
 * A clean, minimalist design for astrophysics researcher
 * Color palette inspired by the cosmos
 */

/* ================================
   CSS Custom Properties (Variables)
   ================================ */
:root {
  /* Primary Colors */
  --color-primary: #1e3a5f;          /* Deep space blue */
  --color-primary-light: #2d5a87;    /* Lighter blue */
  --color-primary-dark: #0f1f33;     /* Darker blue */

  /* Accent Colors */
  --color-accent: #c9a227;           /* Golden star */
  --color-accent-light: #e6c84a;     /* Light gold */

  /* Background Colors */
  --color-bg-primary: #ffffff;       /* Clean white */
  --color-bg-secondary: #f5f7fa;     /* Soft grey */
  --color-bg-dark: #1a1a2e;          /* Dark section */

  /* Text Colors */
  --color-text-primary: #2d3748;     /* Main text */
  --color-text-secondary: #4a5568;   /* Secondary text */
  --color-text-light: #718096;       /* Light text */
  --color-text-inverse: #f7fafc;     /* Text on dark bg */

  /* Education Page Accent - Slightly different to distinguish */
  --color-edu-accent: #2a7d6e;       /* Teal green */
  --color-edu-accent-light: #3d9a89; /* Light teal */

  /* Typography */
  --font-heading: 'Playfair Display', Georgia, 'Times New Roman', serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;

  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;

  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;

  /* Layout */
  --max-width: 1100px;
  --nav-height: 70px;
}

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

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

body {
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.7;
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

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

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-primary-dark);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

p {
  margin-bottom: var(--spacing-md);
}

ul, ol {
  padding-left: var(--spacing-xl);
}

li {
  margin-bottom: var(--spacing-sm);
}

/* ================================
   Layout Utilities
   ================================ */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-xl);
}

.section {
  padding: var(--spacing-3xl) 0;
}

.section-alt {
  background-color: var(--color-bg-secondary);
}

/* ================================
   Navigation
   ================================ */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background-color: var(--color-bg-primary);
  border-bottom: 1px solid rgba(0, 0, 0, 0.08);
  z-index: 1000;
  transition: box-shadow var(--transition-base);
}

.nav.scrolled {
  box-shadow: var(--shadow-md);
}

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

.nav-logo {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-primary);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--spacing-lg);
  list-style: none;
  padding: 0;
  margin: 0;
}

.nav-links li {
  margin: 0;
}

.nav-link {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

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

.nav-link--highlight {
  background-color: var(--color-primary);
  color: var(--color-text-inverse) !important;
}

.nav-link--highlight:hover {
  background-color: var(--color-primary-light);
  color: var(--color-text-inverse) !important;
}

/* Mobile Navigation */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 30px;
  height: 30px;
  background: none;
  border: none;
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  width: 100%;
  height: 2px;
  background-color: var(--color-primary);
  transition: all var(--transition-fast);
}

/* ================================
   Hero Section
   ================================ */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: var(--nav-height);
  background: transparent;
  position: relative;
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: var(--spacing-3xl);
  align-items: center;
}

.hero-text h1 {
  font-size: 3rem;
  margin-bottom: var(--spacing-md);
  color: var(--color-primary-dark);
}

.hero-text .subtitle {
  font-size: 1.25rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-lg);
  font-weight: 400;
}

.hero-text .intro {
  font-size: 1.1rem;
  color: var(--color-text-primary);
  margin-bottom: var(--spacing-xl);
  max-width: 600px;
}

.hero-image {
  position: relative;
}

.hero-image img {
  width: 280px;
  height: 280px;
  border-radius: 50%;
  object-fit: cover;
  border: 4px solid var(--color-primary);
  box-shadow: var(--shadow-lg);
}

.hero-buttons {
  display: flex;
  gap: var(--spacing-md);
  flex-wrap: wrap;
}

/* ================================
   Buttons
   ================================ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) var(--spacing-xl);
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 500;
  border-radius: var(--radius-md);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
}

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

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

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

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

.btn-accent {
  background-color: var(--color-accent);
  color: var(--color-primary-dark);
  border-color: var(--color-accent);
}

.btn-accent:hover {
  background-color: var(--color-accent-light);
  border-color: var(--color-accent-light);
}

/* ================================
   Section Headers
   ================================ */
.section-header {
  text-align: center;
  margin-bottom: var(--spacing-3xl);
}

.section-header h2 {
  font-size: 2.25rem;
  margin-bottom: var(--spacing-sm);
  position: relative;
  display: inline-block;
}

.section-header h2::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background-color: var(--color-accent);
  border-radius: 2px;
}

.section-header p {
  color: var(--color-text-secondary);
  font-size: 1.1rem;
  max-width: 600px;
  margin: var(--spacing-lg) auto 0;
}

/* ================================
   Timeline (Positions, Education)
   ================================ */
.timeline {
  position: relative;
  max-width: 800px;
  margin: 0 auto;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background-color: var(--color-primary);
  opacity: 0.2;
}

.timeline-item {
  position: relative;
  padding-left: var(--spacing-2xl);
  padding-bottom: var(--spacing-xl);
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -5px;
  top: 5px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background-color: var(--color-primary);
}

.timeline-date {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: var(--spacing-xs);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.timeline-title {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--color-primary-dark);
  margin-bottom: var(--spacing-xs);
}

.timeline-subtitle {
  font-size: 1rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-sm);
}

.timeline-description {
  font-size: 0.95rem;
  color: var(--color-text-primary);
}

/* ================================
   Publications List
   ================================ */
.publications-list {
  max-width: 900px;
  margin: 0 auto;
}

.publication-item {
  padding: var(--spacing-lg);
  background-color: var(--color-bg-primary);
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-md);
  border-left: 4px solid var(--color-accent);
  transition: box-shadow var(--transition-fast);
}

.publication-item:hover {
  box-shadow: var(--shadow-md);
}

.publication-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-primary-dark);
  margin-bottom: var(--spacing-sm);
}

.publication-title a {
  color: inherit;
}

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

.publication-authors {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-xs);
}

.publication-venue {
  font-size: 0.9rem;
  color: var(--color-text-light);
  font-style: italic;
}

.publication-links {
  margin-top: var(--spacing-sm);
  display: flex;
  gap: var(--spacing-md);
}

.publication-link {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-primary);
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.publication-link:hover {
  color: var(--color-accent);
}

/* ================================
   Teaching List
   ================================ */
.teaching-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
  max-width: 900px;
  margin: 0 auto;
}

.teaching-item {
  padding: var(--spacing-lg);
  background-color: var(--color-bg-primary);
  border-radius: var(--radius-md);
  border: 1px solid rgba(0, 0, 0, 0.08);
  transition: all var(--transition-fast);
}

.teaching-item:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.teaching-course {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-primary-dark);
  margin-bottom: var(--spacing-xs);
}

.teaching-role {
  font-size: 0.95rem;
  color: var(--color-accent);
  font-weight: 500;
  margin-bottom: var(--spacing-xs);
}

.teaching-institution {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}

.teaching-date {
  font-size: 0.85rem;
  color: var(--color-text-light);
  margin-top: var(--spacing-sm);
}

/* ================================
   Conferences List
   ================================ */
.conferences-list {
  max-width: 800px;
  margin: 0 auto;
}

.conference-year {
  margin-bottom: var(--spacing-xl);
}

.conference-year-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: var(--spacing-md);
  padding-bottom: var(--spacing-sm);
  border-bottom: 2px solid var(--color-bg-secondary);
}

.conference-item {
  padding: var(--spacing-md) 0;
  border-bottom: 1px solid var(--color-bg-secondary);
}

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

.conference-name {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-primary-dark);
  margin-bottom: var(--spacing-xs);
}

.conference-talk {
  font-size: 0.95rem;
  color: var(--color-text-primary);
  font-style: italic;
  margin-bottom: var(--spacing-xs);
}

.conference-details {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}

/* ================================
   Page Switcher (Astro ↔ Education)
   ================================ */
.page-switcher {
  position: fixed;
  bottom: var(--spacing-xl);
  right: var(--spacing-xl);
  z-index: 999;
}

.page-switcher-btn {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) var(--spacing-lg);
  background-color: var(--color-primary);
  color: var(--color-text-inverse);
  border: none;
  border-radius: 50px;
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  box-shadow: var(--shadow-lg);
  transition: all var(--transition-fast);
  text-decoration: none;
}

.page-switcher-btn:hover {
  background-color: var(--color-primary-light);
  color: var(--color-text-inverse);
  transform: translateY(-2px);
}

.page-switcher-btn svg {
  width: 18px;
  height: 18px;
}

/* Education Page Specific Styles */
.edu-page .page-switcher-btn {
  background-color: var(--color-edu-accent);
}

.edu-page .page-switcher-btn:hover {
  background-color: var(--color-edu-accent-light);
}

/* ================================
   Footer
   ================================ */
.footer {
  background-color: var(--color-bg-dark);
  color: var(--color-text-inverse);
  padding: var(--spacing-2xl) 0;
  margin-top: var(--spacing-3xl);
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--spacing-lg);
}

.footer-text {
  font-size: 0.9rem;
  color: rgba(255, 255, 255, 0.7);
}

.footer-links {
  display: flex;
  gap: var(--spacing-lg);
}

.footer-link {
  color: rgba(255, 255, 255, 0.7);
  font-size: 0.9rem;
  transition: color var(--transition-fast);
}

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

/* ================================
   Education Page Specific
   ================================ */
.edu-page {
  --color-accent: var(--color-edu-accent);
  --color-accent-light: var(--color-edu-accent-light);
}

.edu-page .hero {
  background: transparent;
}

.edu-page .section-header h2::after {
  background-color: var(--color-edu-accent);
}

/* Video Embed Container */
.video-showcase {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
  gap: var(--spacing-xl);
  max-width: 1000px;
  margin: 0 auto;
}

.video-item {
  background-color: var(--color-bg-primary);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
  transition: transform var(--transition-fast);
}

.video-item:hover {
  transform: translateY(-4px);
}

.video-embed {
  position: relative;
  padding-bottom: 56.25%; /* 16:9 aspect ratio */
  height: 0;
  overflow: hidden;
}

.video-embed iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: none;
}

.video-info {
  padding: var(--spacing-lg);
}

.video-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-primary-dark);
  margin-bottom: var(--spacing-sm);
}

.video-description {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
}

/* Project Cards */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: var(--spacing-xl);
}

.project-card {
  background-color: var(--color-bg-primary);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  border: 1px solid rgba(0, 0, 0, 0.08);
  transition: all var(--transition-fast);
}

.project-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-edu-accent);
}

.project-icon {
  width: 60px;
  height: 60px;
  background-color: rgba(42, 125, 110, 0.1);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--spacing-lg);
  font-size: 1.5rem;
}

.project-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-primary-dark);
  margin-bottom: var(--spacing-sm);
}

.project-period {
  font-size: 0.9rem;
  color: var(--color-edu-accent);
  font-weight: 500;
  margin-bottom: var(--spacing-md);
}

.project-description {
  font-size: 0.95rem;
  color: var(--color-text-primary);
  line-height: 1.7;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  margin-top: var(--spacing-lg);
}

.project-tag {
  padding: var(--spacing-xs) var(--spacing-md);
  background-color: var(--color-bg-secondary);
  color: var(--color-text-secondary);
  font-size: 0.8rem;
  border-radius: 20px;
  font-weight: 500;
}

/* ================================
   Scroll to Top Button
   ================================ */
.scroll-top {
  position: fixed;
  bottom: var(--spacing-xl);
  left: var(--spacing-xl);
  width: 45px;
  height: 45px;
  background-color: var(--color-primary);
  color: var(--color-text-inverse);
  border: none;
  border-radius: 50%;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-md);
  z-index: 998;
}

.scroll-top.visible {
  opacity: 1;
  visibility: visible;
}

.scroll-top:hover {
  background-color: var(--color-primary-light);
  transform: translateY(-3px);
}

.scroll-top svg {
  width: 20px;
  height: 20px;
}

/* ================================
   Section Navigation (Side dots)
   ================================ */
.section-nav {
  position: fixed;
  right: var(--spacing-xl);
  top: 50%;
  transform: translateY(-50%);
  z-index: 998;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.section-nav-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background-color: var(--color-text-light);
  opacity: 0.4;
  cursor: pointer;
  transition: all var(--transition-fast);
  position: relative;
}

.section-nav-dot:hover,
.section-nav-dot.active {
  opacity: 1;
  background-color: var(--color-primary);
  transform: scale(1.2);
}

.section-nav-dot::before {
  content: attr(data-label);
  position: absolute;
  right: 25px;
  top: 50%;
  transform: translateY(-50%);
  white-space: nowrap;
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  background-color: var(--color-bg-primary);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-sm);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-fast);
}

.section-nav-dot:hover::before {
  opacity: 1;
  visibility: visible;
}

/* ================================
   Responsive Design
   ================================ */
@media (max-width: 900px) {
  :root {
    --nav-height: 60px;
  }

  h1 { font-size: 2rem; }
  h2 { font-size: 1.75rem; }

  .hero {
    /* On mobile, don't center vertically - align to top to prevent overlap */
    align-items: flex-start;
    padding-top: calc(var(--nav-height) + var(--spacing-xl));
  }

  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
    gap: var(--spacing-xl);
  }

  .hero-text h1 {
    font-size: 2.25rem;
  }

  .hero-text .intro {
    margin-left: auto;
    margin-right: auto;
  }

  .hero-image {
    order: -1;
  }

  .hero-image img {
    margin: 0 auto;
    width: 220px;
    height: 220px;
  }

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

  .nav-links {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background-color: var(--color-bg-primary);
    flex-direction: column;
    padding: var(--spacing-lg);
    gap: var(--spacing-sm);
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
    box-shadow: var(--shadow-md);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
  }

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

  .nav-toggle {
    display: flex;
  }

  .section-nav {
    display: none;
  }

  .video-showcase {
    grid-template-columns: 1fr;
  }

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

  .footer-content {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 600px) {
  .container {
    padding: 0 var(--spacing-md);
  }

  .section {
    padding: var(--spacing-2xl) 0;
  }

  .hero-text h1 {
    font-size: 1.75rem;
  }

  .hero-text .subtitle {
    font-size: 1.1rem;
  }

  .btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 0.9rem;
  }

  .timeline::before {
    display: none;
  }

  .timeline-item {
    padding-left: 0;
  }

  .timeline-item::before {
    display: none;
  }

  .page-switcher {
    bottom: var(--spacing-md);
    right: var(--spacing-md);
  }

  .scroll-top {
    bottom: var(--spacing-md);
    left: var(--spacing-md);
    width: 40px;
    height: 40px;
  }
}

/* ================================
   Education/Outreach Page Toggle
   When body has class 'outreach-disabled', hide all outreach links
   ================================ */
.outreach-disabled .nav-link--highlight[href="education.html"],
.outreach-disabled .page-switcher {
  display: none !important;
}

/* ================================
   Print Styles
   ================================ */
@media print {
  .nav,
  .page-switcher,
  .scroll-top,
  .section-nav {
    display: none !important;
  }

  .hero {
    min-height: auto;
    padding-top: 0;
  }

  .section {
    padding: var(--spacing-lg) 0;
    page-break-inside: avoid;
  }

  body {
    font-size: 12pt;
  }
}