:root {
  --bg-color: #fdfcf0;
  --text-color: #333;
  --header-bg: #8c1b1b;
  --nav-bg: #2d5a27;
  --accent-color: #e0d0b0;
  --link-color: #1a73e8;
  --card-bg: #ffffff;
  --border-color: #ddd;
}

body {
  font-family: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', Meiryo, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.8;
  margin: 0;
  padding: 0;
  font-size: 18px; /* Increased for readability */
}

header {
  background-color: var(--header-bg);
  color: white;
  padding: 20px;
  text-align: center;
  border-bottom: 5px solid var(--accent-color);
}

header h1 {
  margin: 0;
  font-size: 2.5rem;
  letter-spacing: 2px;
}

nav {
  background-color: var(--nav-bg);
  position: sticky;
  top: 0;
  z-index: 1000;
}

nav ul {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  margin: 0;
  padding: 0;
  list-style: none;
}

nav li {
  margin: 0;
}

nav a {
  display: block;
  color: white;
  padding: 15px 20px;
  text-decoration: none;
  font-weight: bold;
  transition: background 0.3s;
}

nav a:hover {
  background-color: rgba(255, 255, 255, 0.1);
  text-decoration: underline;
}

main {
  max-width: 1000px;
  margin: 30px auto;
  padding: 0 20px;
}

section {
  background-color: var(--card-bg);
  padding: 30px;
  margin-bottom: 30px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}

h2 {
  color: var(--header-bg);
  border-left: 8px solid var(--header-bg);
  padding-left: 15px;
  margin-top: 0;
  font-size: 1.8rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 10px;
}

h3 {
  color: var(--nav-bg);
  font-size: 1.4rem;
  margin-top: 25px;
}

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

.announcement-box {
  background-color: #fff9e6;
  border: 2px solid #f39c12;
  padding: 20px;
  margin-bottom: 20px;
  border-radius: 5px;
}

.announcement-title {
  font-weight: bold;
  color: #d35400;
  display: block;
  margin-bottom: 10px;
  font-size: 1.2rem;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
  margin-top: 20px;
}

.video-item {
  background: #f9f9f9;
  padding: 15px;
  border: 1px solid #eee;
  border-radius: 5px;
}

.video-item iframe {
  width: 100%;
  aspect-ratio: 16 / 9;
  border-radius: 4px;
}

footer {
  text-align: center;
  padding: 40px;
  background-color: #eee;
  margin-top: 50px;
  font-size: 0.9rem;
}

/* For elderly readability */
.large-text {
  font-size: 1.2rem;
}

@media (max-width: 600px) {
  nav ul {
    flex-direction: column;
  }
  nav a {
    text-align: center;
    border-bottom: 1px solid rgba(255,255,255,0.1);
  }
  header h1 {
    font-size: 1.8rem;
  }
}