/* ==========================================================================
   Professor Avi Loeb's Website - Stylesheet
   ========================================================================== */

/* --------------------------------------------------------------------------
   CSS Custom Properties (Design Tokens)
   -------------------------------------------------------------------------- */
:root {
  /* Colors - based on original site */
  --color-primary: #990000;
  --color-link: #6b4226;
  --color-link-hover: #8b5a2b;
  --color-text: #2a2a2a;
  --color-text-light: #555555;
  --color-background: #f6f1e6;
  --color-white: #ffffff;
  --color-accent: #800000;
  --color-divider: #cc0000;
  
  /* Typography */
  --font-family-serif: "Georgia", "Times New Roman", serif;
  --font-family-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  
  --font-size-xs: 0.75rem;    /* 12px */
  --font-size-sm: 0.875rem;   /* 14px */
  --font-size-base: 1rem;     /* 16px */
  --font-size-lg: 1.125rem;   /* 18px */
  --font-size-xl: 1.25rem;    /* 20px */
  --font-size-2xl: 1.5rem;    /* 24px */
  --font-size-3xl: 1.875rem;  /* 30px */
  --font-size-4xl: 2.25rem;   /* 36px */
  
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.65;
  
  /* Spacing */
  --space-1: 0.25rem;   /* 4px */
  --space-2: 0.5rem;    /* 8px */
  --space-3: 0.75rem;   /* 12px */
  --space-4: 1rem;      /* 16px */
  --space-5: 1.25rem;   /* 20px */
  --space-6: 1.5rem;    /* 24px */
  --space-8: 2rem;      /* 32px */
  --space-10: 2.5rem;   /* 40px */
  --space-12: 3rem;     /* 48px */
  --space-16: 4rem;     /* 64px */
  
  /* Layout */
  --max-width-content: 1100px;
  --max-width-narrow: 800px;
  
  /* Borders */
  --border-radius-sm: 4px;
  --border-radius-md: 8px;
  --border-radius-lg: 12px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
}

/* --------------------------------------------------------------------------
   CSS Reset / Normalization
   -------------------------------------------------------------------------- */
*, *::before, *::after {
  box-sizing: border-box;
}

* {
  margin: 0;
  padding: 0;
}

html {
  color-scheme: light;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  font-family: var(--font-family-serif);
  font-size: var(--font-size-base);
  line-height: var(--line-height-relaxed);
  color: var(--color-text);
  background-color: var(--color-background);
  background-image: url("newb.jpg");
  background-repeat: repeat;
  background-position: top left;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img, picture, video, canvas, svg {
  display: block;
  max-width: 100%;
  height: auto;
}

input, button, textarea, select {
  font: inherit;
}

p, h1, h2, h3, h4, h5, h6 {
  overflow-wrap: break-word;
}

/* --------------------------------------------------------------------------
   Typography
   -------------------------------------------------------------------------- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-family-serif);
  font-weight: 700;
  line-height: var(--line-height-tight);
  color: var(--color-text);
}

h1 {
  font-size: var(--font-size-3xl);
  margin-bottom: var(--space-6);
}

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

h3 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-3);
}

h4 {
  font-size: var(--font-size-lg);
  margin-bottom: var(--space-2);
}

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

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

a:hover,
a:focus {
  color: var(--color-link-hover);
  text-decoration: underline;
}

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

/* Lists */
ul, ol {
  padding-left: var(--space-6);
  margin-bottom: var(--space-4);
}

li {
  margin-bottom: var(--space-2);
}

/* --------------------------------------------------------------------------
   Navigation Bar
   -------------------------------------------------------------------------- */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-primary);
  box-shadow: var(--shadow-md);
}

.navbar__container {
  max-width: var(--max-width-content);
  margin: 0 auto;
  padding: 0 var(--space-4);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
}

.navbar__brand {
  color: var(--color-white);
  font-size: var(--font-size-lg);
  font-weight: 700;
  padding: var(--space-3) 0;
  text-decoration: none;
}

.navbar__brand:hover {
  color: var(--color-white);
  text-decoration: none;
}

.navbar__menu {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: var(--space-1);
}

.navbar__menu li {
  margin: 0;
}

.navbar__menu a {
  display: block;
  padding: var(--space-3) var(--space-3);
  color: rgba(255, 255, 255, 0.9);
  font-size: var(--font-size-sm);
  text-decoration: none;
  transition: background var(--transition-fast), color var(--transition-fast);
  border-radius: var(--border-radius-sm);
}

.navbar__menu a:hover,
.navbar__menu a:focus {
  background: rgba(255, 255, 255, 0.15);
  color: var(--color-white);
  text-decoration: none;
}

.navbar__toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 30px;
  height: 30px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.navbar__toggle span {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--color-white);
  border-radius: 2px;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

/* Mobile navigation */
@media (max-width: 768px) {
  .navbar__toggle {
    display: flex;
  }

  .navbar__menu {
    display: none;
    width: 100%;
    flex-direction: column;
    padding: var(--space-2) 0;
    gap: 0;
  }

  .navbar__menu.is-open {
    display: flex;
  }

  .navbar__menu a {
    padding: var(--space-3) var(--space-4);
    border-radius: 0;
  }

  .navbar__toggle[aria-expanded="true"] span:nth-child(1) {
    transform: rotate(45deg) translate(4px, 4px);
  }

  .navbar__toggle[aria-expanded="true"] span:nth-child(2) {
    opacity: 0;
  }

  .navbar__toggle[aria-expanded="true"] span:nth-child(3) {
    transform: rotate(-45deg) translate(4px, -4px);
  }
}

/* --------------------------------------------------------------------------
   Layout Components
   -------------------------------------------------------------------------- */

/* Page wrapper */
.page {
  max-width: var(--max-width-content);
  margin: 0 auto;
  padding: var(--space-6) var(--space-6) var(--space-10);
}

/* Skip link for accessibility */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-primary);
  color: var(--color-white);
  padding: var(--space-2) var(--space-4);
  z-index: 100;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 0;
}

/* Section styles */
.section {
  margin-bottom: var(--space-12);
  padding-bottom: var(--space-8);
  border-bottom: 5px solid var(--color-divider);
}

.section:last-child {
  border-bottom: none;
}

.section-title {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--color-primary);
  text-transform: uppercase;
  margin-bottom: var(--space-6);
  padding-bottom: var(--space-2);
  border-bottom: 2px solid var(--color-divider);
}

/* Divider */
.divider {
  height: 5px;
  background-color: var(--color-divider);
  border: none;
  margin: var(--space-6) 0;
}

.divider--thin {
  height: 2px;
}

/* --------------------------------------------------------------------------
   Hero Section
   -------------------------------------------------------------------------- */
.hero {
  margin-bottom: var(--space-8);
}

.hero__header {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: var(--space-6);
  align-items: start;
  margin-bottom: var(--space-6);
}

@media (max-width: 768px) {
  .hero__header {
    grid-template-columns: 1fr;
    text-align: center;
  }
}

.hero__logos {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-4);
}

.hero__logos img {
  max-height: 50px;
  width: auto;
}

.hero__logos a {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  font-size: var(--font-size-xs);
  max-width: 80px;
}

.hero__logos span {
  display: block;
  line-height: 1.2;
  margin-top: var(--space-1);
}

.hero__info {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.hero__title {
  font-size: var(--font-size-2xl);
  color: var(--color-primary);
  text-align: center;
  margin-bottom: var(--space-4);
}

.hero__contact {
  font-size: var(--font-size-sm);
  display: grid;
  grid-template-columns: auto 1fr;
  gap: var(--space-1) var(--space-3);
  align-items: baseline;
}

.hero__contact-row {
  display: contents;
}

.hero__contact-label {
  font-weight: 600;
  text-align: right;
  white-space: nowrap;
}

.hero__photo {
  max-width: 375px;
}

.hero__photo img {
  width: 100%;
  height: auto;
}

/* Bio section */
.bio {
  font-size: var(--font-size-lg);
  line-height: var(--line-height-relaxed);
}

.bio p {
  margin-bottom: var(--space-4);
}

/* Staff contacts */
.staff-contacts {
  font-size: var(--font-size-sm);
  margin-top: var(--space-6);
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-6);
}

.staff-contacts .staff-card {
  display: inline-block;
  min-width: 180px;
}

.staff-contacts h4 {
  font-size: var(--font-size-sm);
  margin-bottom: 0;
}

.staff-contacts p {
  margin-bottom: 0;
}

/* --------------------------------------------------------------------------
   News Section
   -------------------------------------------------------------------------- */
.news-list {
  list-style: none;
  padding-left: 0;
}

.news-list li {
  margin-bottom: var(--space-3);
  padding-left: var(--space-4);
  position: relative;
}

.news-list li::before {
  content: "*";
  position: absolute;
  left: 0;
  color: var(--color-primary);
  font-weight: bold;
}

.news-list a {
  display: block;
}

.news-list strong {
  display: block;
}

.news-date {
  font-size: var(--font-size-sm);
  color: var(--color-text-light);
}

/* Year groups for news */
.news-year {
  margin-bottom: var(--space-8);
}

.news-year__title {
  font-size: var(--font-size-lg);
  color: var(--color-primary);
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--color-divider);
}

/* Collapsible sections */
.collapsible {
  margin-bottom: var(--space-4);
}

.collapsible__toggle {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: var(--space-3) var(--space-4);
  background: rgba(153, 0, 0, 0.1);
  border: 1px solid var(--color-divider);
  border-radius: var(--border-radius-sm);
  cursor: pointer;
  font-family: var(--font-family-serif);
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--color-primary);
  text-align: left;
  transition: background var(--transition-fast);
}

.collapsible__toggle:hover {
  background: rgba(153, 0, 0, 0.15);
}

.collapsible__toggle::after {
  content: "+";
  font-size: var(--font-size-xl);
  font-weight: bold;
}

.collapsible__toggle[aria-expanded="true"]::after {
  content: "−";
}

.collapsible__content {
  display: none;
  padding: var(--space-4);
  border: 1px solid var(--color-divider);
  border-top: none;
  border-radius: 0 0 var(--border-radius-sm) var(--border-radius-sm);
}

.collapsible__content.is-open {
  display: block;
}

/* --------------------------------------------------------------------------
   Books Section
   -------------------------------------------------------------------------- */
.books-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: var(--space-6);
}

.book-card {
  text-align: center;
}

.book-card__cover {
  margin-bottom: var(--space-3);
  transition: transform var(--transition-normal);
}

.book-card:hover .book-card__cover {
  transform: scale(1.02);
}

.book-card__cover img {
  max-width: 100%;
  height: auto;
  box-shadow: var(--shadow-md);
}

.book-card__title {
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-bottom: var(--space-1);
}

.book-card__details {
  font-size: var(--font-size-xs);
  color: var(--color-text-light);
}

/* Featured book (bestseller) */
.book-featured {
  grid-column: 1 / -1;
  display: flex;
  gap: var(--space-6);
  align-items: center;
  padding: var(--space-6);
  background: rgba(153, 0, 0, 0.05);
  border-radius: var(--border-radius-md);
  margin-bottom: var(--space-6);
}

@media (max-width: 600px) {
  .book-featured {
    flex-direction: column;
    text-align: center;
  }
}

.book-featured__cover img {
  max-width: 200px;
  box-shadow: var(--shadow-lg);
}

.book-featured__info h3 {
  color: var(--color-primary);
  margin-bottom: var(--space-2);
}

/* --------------------------------------------------------------------------
   Videos / Media Section
   -------------------------------------------------------------------------- */
.videos-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--space-6);
}

.video-card {
  background: var(--color-white);
  border-radius: var(--border-radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.video-card video {
  width: 100%;
  height: auto;
}

.video-card__title {
  padding: var(--space-3) var(--space-4);
  font-size: var(--font-size-sm);
  font-style: italic;
  background: var(--color-background);
}

/* --------------------------------------------------------------------------
   Publications / Links Section
   -------------------------------------------------------------------------- */
.publications-list {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: var(--space-2) var(--space-4);
  align-items: baseline;
}

.publications-list dt {
  font-size: var(--font-size-lg);
  color: var(--color-accent);
  text-align: right;
}

.publications-list dd {
  font-size: var(--font-size-sm);
  margin-bottom: var(--space-4);
}

/* Profile links grid */
.profiles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: var(--space-4);
}

.profile-link {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3);
  background: var(--color-white);
  border-radius: var(--border-radius-sm);
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition-fast);
}

.profile-link:hover {
  box-shadow: var(--shadow-md);
  text-decoration: none;
}

/* --------------------------------------------------------------------------
   Graduate Students Section
   -------------------------------------------------------------------------- */
.students-section {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: var(--space-6);
  align-items: start;
}

@media (max-width: 768px) {
  .students-section {
    grid-template-columns: 1fr;
  }
}

/* --------------------------------------------------------------------------
   Conferences Section
   -------------------------------------------------------------------------- */
.conferences-list {
  display: grid;
  gap: var(--space-4);
}

.conference-item {
  padding: var(--space-3);
  background: var(--color-white);
  border-radius: var(--border-radius-sm);
  box-shadow: var(--shadow-sm);
}

.conference-item__date {
  font-size: var(--font-size-sm);
  color: var(--color-text-light);
  margin-bottom: var(--space-1);
}

.conference-item__title {
  font-weight: 600;
  color: var(--color-link);
}

/* --------------------------------------------------------------------------
   Lectures Section
   -------------------------------------------------------------------------- */
.lectures-list {
  list-style: none;
  padding-left: 0;
}

.lectures-list li {
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-4);
  border-bottom: 1px solid rgba(0, 0, 0, 0.1);
}

.lectures-list li:last-child {
  border-bottom: none;
}

.lecture-title {
  font-style: italic;
}

.lecture-venue {
  font-size: var(--font-size-sm);
  color: var(--color-text-light);
}

/* --------------------------------------------------------------------------
   Featured Images / Sidebar
   -------------------------------------------------------------------------- */
.featured-images {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-6);
}

.featured-images img {
  width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: var(--border-radius-sm);
  box-shadow: var(--shadow-sm);
}

.featured-images a {
  display: block;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.featured-images a:hover {
  transform: translateY(-2px);
}

.featured-images a:hover img {
  box-shadow: var(--shadow-md);
}

/* --------------------------------------------------------------------------
   Scroll to Top Button
   -------------------------------------------------------------------------- */
.scroll-to-top {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  width: 48px;
  height: 48px;
  background: var(--color-primary);
  color: var(--color-white);
  border: none;
  border-radius: 50%;
  font-size: var(--font-size-xl);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: opacity var(--transition-normal), transform var(--transition-normal), visibility var(--transition-normal), background var(--transition-fast);
  box-shadow: var(--shadow-lg);
  z-index: 99;
}

.scroll-to-top:hover {
  background: var(--color-accent);
}

.scroll-to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.site-footer {
  text-align: center;
  padding: var(--space-8) var(--space-4);
  font-size: var(--font-size-sm);
  font-style: italic;
  color: var(--color-text-light);
  border-top: 5px solid var(--color-divider);
  margin-top: var(--space-8);
}

.site-footer a {
  color: var(--color-text-light);
}

/* --------------------------------------------------------------------------
   Utility Classes
   -------------------------------------------------------------------------- */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.text-sm { font-size: var(--font-size-sm); }
.text-lg { font-size: var(--font-size-lg); }
.text-xl { font-size: var(--font-size-xl); }

.text-primary { color: var(--color-primary); }
.text-accent { color: var(--color-accent); }
.text-muted { color: var(--color-text-light); }

.font-bold { font-weight: 700; }
.font-normal { font-weight: 400; }

.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }

.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }

.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;
}

/* --------------------------------------------------------------------------
   Print Styles
   -------------------------------------------------------------------------- */
@media print {
  body {
    background: white;
    color: black;
  }
  
  .skip-link,
  .collapsible__toggle::after {
    display: none;
  }
  
  a {
    color: black;
    text-decoration: underline;
  }
  
  .section {
    page-break-inside: avoid;
  }
}