/* style.css - Northwestern Delta Lab Style (Multi-Page) */
:root {
  /* Northwestern Brand Colors */
  --northwestern-purple: #4E2A84;
  --purple-90: #836EAA;
  --purple-80: #665A94;
  --purple-70: #574A85;
  --purple-light: #B6ACD1;
  --purple-lighter: #E4E0EE;
  
  /* Neutral Colors */
  --text-dark: #342F2E;
  --text-medium: #716C6B;
  --text-light: #999999;
  --border-light: #D8D6D6;
  --bg-gray: #F5F5F5;
  --white: #FFFFFF;
  
  /* Spacing */
  --section-padding: 5rem;
  --container-max: 1200px;
  
  /* Typography */
  --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  
  /* Transitions */
  --transition: all 0.3s ease;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: var(--font-primary);
  line-height: 1.6;
  color: var(--text-dark);
  background: var(--white);
  -webkit-font-smoothing: antialiased;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* ===== NAVIGATION ===== */
.main-nav {
  background: var(--white);
  border-bottom: 2px solid var(--northwestern-purple);
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  box-shadow: 0 2px 10px rgba(78, 42, 132, 0.1);
}

.nav-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-logo a {
  font-size: 1.0rem;
  font-weight: 700;
  color: var(--northwestern-purple);
  text-decoration: none;
  letter-spacing: -0.5px;
}

.nav-logo a:hover {
  opacity: 0.8;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: 1.5rem;
  margin: 0;
  padding: 0;
}

.nav-link {
  text-decoration: none;
  color: var(--text-dark);
  font-weight: 500;
  font-size: 0.95rem;
  padding: 0.5rem 0;
  position: relative;
  transition: var(--transition);
}

.nav-link:hover,
.nav-link.active {
  color: var(--northwestern-purple);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--northwestern-purple);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.nav-toggle span {
  width: 25px;
  height: 3px;
  background: var(--northwestern-purple);
  transition: var(--transition);
  border-radius: 2px;
}

/* ===== MAIN CONTENT ===== */
main {
  flex: 1;
  margin-top: 73px; /* Height of fixed nav */
}

.page-header {
  background: linear-gradient(135deg, var(--northwestern-purple) 0%, var(--purple-70) 100%);
  color: var(--white);
  padding: 4rem 2rem;
  text-align: center;
}

.page-header h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 1rem;
  letter-spacing: -0.5px;
}

.page-header p {
  font-size: 1.2rem;
  max-width: 700px;
  margin: 0 auto;
  opacity: 0.95;
  line-height: 1.6;
}

/* ===== SECTIONS ===== */
section {
  padding: var(--section-padding) 2rem;
  max-width: var(--container-max);
  margin: 0 auto;
}

section h2 {
  font-size: 2.25rem;
  color: var(--northwestern-purple);
  margin-bottom: 2rem;
  font-weight: 700;
  letter-spacing: -0.5px;
}

.section-intro {
  font-size: 1.2rem;
  color: var(--text-medium);
  max-width: 800px;
  margin-bottom: 3rem;
  line-height: 1.7;
}

/* ===== CARDS & GRIDS ===== */
.projects-grid,
.team-grid,
.news-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.project-card,
.team-member,
.news-item,
.pub-item {
  background: var(--white);
  padding: 2rem;
  border-radius: 8px;
  border-left: 4px solid var(--northwestern-purple);
  box-shadow: 0 4px 15px rgba(0,0,0,0.05);
  transition: var(--transition);
}

.project-card:hover,
.team-member:hover,
.news-item:hover,
.pub-item:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 25px rgba(78, 42, 132, 0.15);
  border-left-color: var(--purple-90);
}

.project-card h3,
.team-member h3,
.news-item h3,
.pub-item h3 {
  font-size: 1.4rem;
  color: var(--northwestern-purple);
  margin-bottom: 1rem;
  font-weight: 600;
}

.project-card p,
.team-member p,
.news-item p,
.pub-item p {
  color: var(--text-medium);
  line-height: 1.7;
  margin-bottom: 1rem;
}

/* Tags */
.project-tags {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.tag {
  background: var(--purple-lighter);
  color: var(--northwestern-purple);
  padding: 0.3rem 0.8rem;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
}

/* Team Member */
.team-member {
  text-align: center;
}

.member-avatar {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--northwestern-purple), var(--purple-90));
  margin: 0 auto 1.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--white);
  font-size: 1.8rem;
  font-weight: 600;
}

.member-role {
  color: var(--northwestern-purple);
  font-weight: 500;
  margin-bottom: 1rem;
  font-size: 0.95rem;
}

/* Publications */
.pub-authors {
  color: var(--northwestern-purple);
  font-weight: 500;
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
}

.pub-venue {
  color: var(--text-medium);
  font-style: italic;
  font-size: 0.95rem;
}

.pub-year {
  background: var(--northwestern-purple);
  color: var(--white);
  padding: 0.25rem 0.75rem;
  border-radius: 4px;
  font-size: 0.85rem;
  font-weight: 600;
  display: inline-block;
  margin-top: 0.75rem;
}

/* News */
.news-date {
  color: var(--northwestern-purple);
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* ===== ABOUT PAGE ===== */
.about-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: start;
}

.about-text {
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--text-dark);
}

.about-text p {
  margin-bottom: 1.5rem;
}

.about-text strong {
  color: var(--northwestern-purple);
}

.about-image {
  background: linear-gradient(135deg, var(--purple-lighter), var(--purple-light));
  border-radius: 8px;
  height: 400px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--northwestern-purple);
  font-size: 1.2rem;
  font-weight: 600;
  box-shadow: 0 10px 30px rgba(78, 42, 132, 0.15);
}

/* ===== CONTACT SECTION (on index.html) ===== */
#contact {
  background: var(--bg-gray);
}

.contact-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  margin-top: 2rem;
}

.contact-info h3 {
  font-size: 1.4rem;
  color: var(--northwestern-purple);
  margin-bottom: 1.5rem;
  font-weight: 600;
}

.contact-detail {
  margin-bottom: 2rem;
}

.contact-detail h4 {
  color: var(--text-dark);
  font-size: 1.1rem;
  margin-bottom: 0.75rem;
  font-weight: 600;
}

.contact-detail p {
  color: var(--text-medium);
  line-height: 1.7;
}

.contact-detail a {
  color: var(--northwestern-purple);
  text-decoration: none;
  font-weight: 500;
}

.contact-detail a:hover {
  text-decoration: underline;
}

.contact-form {
  background: var(--white);
  padding: 2.5rem;
  border-radius: 8px;
  border: 1px solid var(--border-light);
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  color: var(--text-dark);
  font-weight: 500;
  font-size: 0.95rem;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.9rem;
  border: 1px solid var(--border-light);
  border-radius: 4px;
  font-family: inherit;
  font-size: 1rem;
  background: var(--white);
  transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--northwestern-purple);
  box-shadow: 0 0 0 3px rgba(78, 42, 132, 0.1);
}

.form-group textarea {
  resize: vertical;
  min-height: 150px;
}

.btn-submit {
  background: var(--northwestern-purple);
  color: var(--white);
  border: none;
  padding: 1rem 2.5rem;
  border-radius: 4px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  width: 100%;
}

.btn-submit:hover {
  background: var(--purple-70);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(78, 42, 132, 0.3);
}

/* ===== FOOTER ===== */
footer {
  background: var(--text-dark);
  color: var(--white);
  padding: 3rem 2rem 2rem;
  text-align: center;
  margin-top: auto;
}

.footer-content {
  max-width: var(--container-max);
  margin: 0 auto;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.footer-links a {
  color: var(--purple-light);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
}

.footer-links a:hover {
  color: var(--white);
}

.footer-text {
  color: var(--text-light);
  font-size: 0.9rem;
  line-height: 1.7;
}

.footer-text a {
  color: var(--purple-light);
  text-decoration: none;
}

/* ===== HERO SECTION (index.html only) ===== */
.hero {
  background: linear-gradient(135deg, var(--northwestern-purple) 0%, var(--purple-70) 100%);
  color: var(--white);
  padding: 10rem 2rem 6rem;
  text-align: center;
}

.hero-content {
  max-width: 900px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
  line-height: 1.2;
  letter-spacing: -1px;
}

.hero-tagline {
  font-size: 1.5rem;
  font-weight: 300;
  margin-bottom: 2rem;
  opacity: 0.95;
  line-height: 1.4;
}

.hero-description {
  font-size: 1.15rem;
  max-width: 750px;
  margin: 0 auto 2.5rem;
  opacity: 0.9;
  line-height: 1.7;
}

.hero-cta {
  display: inline-flex;
  gap: 1rem;
  flex-wrap: wrap;
  justify-content: center;
}

.btn {
  display: inline-block;
  padding: 0.9rem 2rem;
  border-radius: 4px;
  text-decoration: none;
  font-weight: 600;
  font-size: 1rem;
  transition: var(--transition);
  border: 2px solid transparent;
}

.btn-primary {
  background: var(--white);
  color: var(--northwestern-purple);
  border-color: var(--white);
}

.btn-primary:hover {
  background: transparent;
  color: var(--white);
}

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

.btn-secondary:hover {
  background: var(--white);
  color: var(--northwestern-purple);
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 968px) {
  .nav-toggle {
    display: flex;
  }

  .nav-menu {
    position: fixed;
    top: 73px;
    left: 0;
    right: 0;
    background: var(--white);
    flex-direction: column;
    padding: 2rem;
    gap: 1rem;
    border-bottom: 2px solid var(--northwestern-purple);
    box-shadow: 0 4px 10px rgba(0,0,0,0.1);
    transform: translateY(-150%);
    transition: transform 0.3s ease;
    z-index: 999;
  }

  .nav-menu.active {
    transform: translateY(0);
  }

  .nav-link {
    padding: 0.75rem 1rem;
    font-size: 1.1rem;
    border-radius: 4px;
  }

  .nav-link:hover,
  .nav-link.active {
    background: var(--purple-lighter);
  }

  .nav-link.active::after {
    display: none;
  }

  .about-content,
  .contact-container {
    grid-template-columns: 1fr;
    gap: 3rem;
  }

  .about-image {
    height: 300px;
    order: -1;
  }

  section {
    padding: 4rem 1.5rem;
  }

  section h2 {
    font-size: 2rem;
  }

  .page-header {
    padding: 3rem 1.5rem;
  }

  .page-header h1 {
    font-size: 2rem;
  }
}

@media (max-width: 640px) {
  .hero h1 {
    font-size: 2rem;
  }

  .hero-tagline {
    font-size: 1.1rem;
  }

  .hero-description {
    font-size: 1rem;
  }

  .btn {
    padding: 0.75rem 1.5rem;
    font-size: 0.9rem;
  }

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

  .contact-form {
    padding: 1.5rem;
  }
}

/* ===== PRINT STYLES ===== */
@media print {
  .main-nav,
  .hero-cta,
  .contact-form,
  footer {
    display: none;
  }

  .hero,
  .page-header {
    background: var(--northwestern-purple) !important;
    -webkit-print-color-adjust: exact;
    print-color-adjust: exact;
  }

  section {
    page-break-inside: avoid;
  }
}