/*
 * ISU themed styles for the AI in Space poster session
 * Primary colour palette: ISU blue (#001454) and white
 * Typography: Calibri (preferred), Arial, sans-serif
 */

:root {
  --isu-blue: #001454;
  --isu-secondary: #002366;
  --isu-accent: #0a3c86;
  --white: #ffffff;
  --light-bg: #f4f7fb;
  --text-color: #222222;
  --heading-font: 'Calibri', 'Arial', sans-serif;
  --body-font: 'Calibri', 'Arial', sans-serif;
  --card-shadow: 0 12px 24px rgba(0, 20, 84, 0.12);
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  font-family: var(--body-font);
  color: var(--text-color);
  background-color: var(--light-bg);
  line-height: 1.6;
}

header.hero {
  background-image: linear-gradient(135deg, rgba(0, 20, 84, 0.86), rgba(10, 60, 134, 0.78)),
    url('pexels-shashank-brahmavar-737732917-18507019.jpg');
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  color: var(--white);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero-banner {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 1.5rem 1rem 0;
  position: relative;
}

.hero-banner::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, rgba(255,255,255,0), rgba(255,255,255,0.7), rgba(255,255,255,0));
}

.hero-logo {
  max-width: 220px;
  width: 40vw;
  height: auto;
  filter: drop-shadow(0 10px 20px rgba(0,0,0,0.35));
}

.hero-path {
  position: absolute;
  inset: auto 0 -120px 0;
  height: 240px;
  background: radial-gradient(circle at center, rgba(255,255,255,0.12) 0%, rgba(255,255,255,0) 60%);
  pointer-events: none;
}

.hero-content {
  padding: 0 1.5rem 4rem;
  max-width: 840px;
  margin: 0 auto;
}

.hero h1 {
  margin: 1.5rem 0 0.5rem;
  font-size: clamp(2.4rem, 4vw, 3.25rem);
  letter-spacing: 0.015em;
}

.hero .tagline {
  font-size: 1.15rem;
  max-width: 720px;
  margin: 0.75rem auto 0;
}

.hero .date {
  margin-top: 1.5rem;
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: 0.04em;
}

nav.navbar {
  background: var(--isu-secondary);
  padding: 0.75rem 1rem;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 3px 12px rgba(0, 20, 84, 0.2);
}

nav.navbar ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  gap: clamp(0.75rem, 3vw, 2rem);
}

nav.navbar li a {
  color: var(--white);
  text-decoration: none;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  padding: 0.5rem 0.25rem;
  position: relative;
  text-transform: uppercase;
}

nav.navbar li a::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 2px;
  background: var(--white);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform 0.2s ease;
}

nav.navbar li a:hover::after,
nav.navbar li a:focus-visible::after {
  transform: scaleX(1);
}

main {
  max-width: 1100px;
  margin: 2.5rem auto 4rem;
  padding: 0 1.5rem;
}

section {
  margin-bottom: 4rem;
}

section h2 {
  font-size: clamp(1.9rem, 3vw, 2.4rem);
  color: var(--isu-blue);
  margin-bottom: 0.75rem;
  letter-spacing: 0.015em;
}

section h3 {
  font-size: 1.35rem;
  color: var(--isu-secondary);
  margin: 0.75rem 0;
}

section h4 {
  margin: 0.5rem 0 0.25rem;
  color: var(--isu-accent);
  font-weight: 700;
}

table.schedule {
  width: 100%;
  border-collapse: collapse;
  margin-top: 1rem;
  font-size: 0.95rem;
  background: var(--white);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--card-shadow);
}

table.schedule th,
table.schedule td {
  border-bottom: 1px solid #e0e7f5;
  padding: 0.75rem 1rem;
  text-align: left;
}

table.schedule th {
  background-color: var(--isu-secondary);
  color: var(--white);
  font-weight: 700;
}

table.schedule tr:nth-child(even) td {
  background-color: #f1f5ff;
}

ol {
  margin-left: 1.5rem;
}

.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.75rem;
}

.topic {
  background: var(--white);
  border: 1px solid #d9e2ff;
  border-radius: 16px;
  padding: 1.5rem;
  box-shadow: 0 8px 16px rgba(0,0,0,0.06);
}

.topic ul {
  margin: 0;
  padding-left: 1.2rem;
  list-style: disc;
}

.project-directory {
  text-align: center;
}

.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.project-card {
  display: block;
  text-decoration: none;
  background: var(--white);
  color: inherit;
  border-radius: 16px;
  padding: 1.75rem 1.5rem;
  box-shadow: var(--card-shadow);
  border: 1px solid transparent;
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}

.project-card:hover,
.project-card:focus-visible {
  transform: translateY(-4px);
  box-shadow: 0 18px 32px rgba(0, 20, 84, 0.16);
  border-color: rgba(0, 20, 84, 0.35);
}

.evaluation {
  overflow-x: auto;
}

.evaluation-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 1.5rem;
  font-size: 0.95rem;
  background: var(--white);
  border-radius: 16px;
  overflow: hidden;
  box-shadow: var(--card-shadow);
}

.evaluation-table th,
.evaluation-table td {
  border-bottom: 1px solid #e0e7f5;
  padding: 1rem 1.2rem;
  vertical-align: top;
  text-align: left;
}

.evaluation-table th {
  background-color: var(--isu-secondary);
  color: var(--white);
  font-weight: 700;
}

.evaluation-table tr:nth-child(even) td {
  background-color: #f5f8ff;
}

footer {
  background: var(--isu-secondary);
  color: var(--white);
  padding: 1.5rem 1rem;
  font-size: 0.9rem;
}

.footer-content {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
}

.footer-logo {
  width: clamp(140px, 30vw, 220px);
  height: auto;
}

@media (max-width: 720px) {
  nav.navbar ul {
    flex-wrap: wrap;
  }
}

@media (max-width: 480px) {
  .hero-logo {
    max-width: 160px;
  }

  .hero .tagline {
    font-size: 1.05rem;
  }

  .evaluation-table {
    font-size: 0.88rem;
  }
}