:root {
  --primary-color: #003366;      /* Dark Blue */
  --secondary-color: #f4f6f9;    /* Light background gray */
  --accent-color: #d97706;       /* Warm amber for callouts/tags */
  --text-color: #1f2937;         /* Dark slate for high-contrast reading */
  --border-color: #e5e7eb;       /* Soft divider gray */
  --card-bg: #ffffff;
  --header-text: #ffffff;
}

/* Global Reset & Base Styles */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--secondary-color);
  padding: 0;
  margin: 0;
}

/* Page Container */
.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 2rem 1rem;
}

/* Site Header & Branding Components */
header,
.site-header {
  background-color: var(--primary-color);
  color: var(--header-text);
  padding: 2.5rem 1.5rem;
  text-align: center;
  border-bottom: 4px solid var(--accent-color);
}

.dept-title {
  font-size: 0.95rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  opacity: 0.85;
  margin-bottom: 0.5rem;
  font-weight: 600;
}

.site-header h1,
header h1 {
  font-size: 2.2rem;
  margin-bottom: 0.5rem;
  font-weight: 700;
  color: var(--header-text);
}

.site-header p,
header p {
  font-size: 1.1rem;
  opacity: 0.95;
  max-width: 700px;
  margin: 0 auto;
}

/* General Layout & Cards */
.card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.card h2 {
  color: var(--primary-color);
  font-size: 1.5rem;
  margin-bottom: 1rem;
  border-bottom: 2px solid var(--secondary-color);
  padding-bottom: 0.5rem;
}

.card h3 {
  color: var(--primary-color);
  font-size: 1.2rem;
  margin: 1.25rem 0 0.5rem 0;
}

/* Log Entries (mb96log) */
.log-entry {
  border-left: 4px solid var(--primary-color);
}

.log-entry-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.timestamp {
  font-weight: bold;
  color: var(--primary-color);
}

/* Category Badges & Tags */
.tag {
  display: inline-block;
  background-color: #e0f2fe;
  color: #0369a1;
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: 9999px;
  text-transform: uppercase;
}

.tag.aurora {
  background-color: #fef3c7;
  color: #b45309;
}

.tag.geomagnetic {
  background-color: #fce7f3;
  color: #be185d;
}

.tag.vlf {
  background-color: #dcfce7;
  color: #15803d;
}

/* Data Boxes & Callouts */
.data-box,
.ibc-box {
  background-color: var(--secondary-color);
  border: 1px solid var(--border-color);
  border-radius: 4px;
  padding: 1rem;
  margin: 1rem 0;
  font-size: 0.95rem;
}

.data-box h4,
.ibc-box h4 {
  margin-bottom: 0.5rem;
  color: var(--primary-color);
}

/* Audio Catalog Items (Index Page) */
.audio-item {
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 0;
}

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

.audio-title {
  font-weight: bold;
  color: var(--primary-color);
}

.audio-meta {
  font-size: 0.85rem;
  color: #6b7280;
  margin-bottom: 0.5rem;
}

/* Media & Figures */
figure {
  margin: 1.5rem 0;
  text-align: center;
}

figure img {
  max-width: 100%;
  height: auto;
  border-radius: 4px;
  border: 1px solid var(--border-color);
}

figcaption {
  font-size: 0.85rem;
  color: #6b7280;
  margin-top: 0.5rem;
  font-style: italic;
}

/* Blockquotes & Lists */
blockquote {
  border-left: 3px solid var(--accent-color);
  padding-left: 1rem;
  margin: 1rem 0;
  color: #4b5563;
  font-style: italic;
}

ul, ol {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
}

li {
  margin-bottom: 0.25rem;
}

/* Tables */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
}

th, td {
  border: 1px solid var(--border-color);
  padding: 0.5rem 0.75rem;
  text-align: left;
}

th {
  background-color: var(--secondary-color);
  color: var(--primary-color);
}

/* Navigation & Footer */
nav.nav-links {
  margin: 1rem 0 2rem 0;
  display: flex;
  gap: 1rem;
  justify-content: center;
}

nav.nav-links a {
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 600;
  padding: 0.5rem 1rem;
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 4px;
  transition: background-color 0.2s, border-color 0.2s;
}

nav.nav-links a:hover {
  background-color: #e2e8f0;
  border-color: #cbd5e1;
}

footer {
  text-align: center;
  padding: 2rem 1rem;
  font-size: 0.9rem;
  color: #6b7280;
  border-top: 1px solid var(--border-color);
  margin-top: 2rem;
}