:root {
  --color-primary: #455B90;
  --color-accent: #FF9933;
  --color-secondary: #D7D39D;
  --color-bg: #FFFFEE;
  --color-link: #FF0011;
  --color-divider: #6679A1;
  --color-muted: #97A5C5;
  --color-text: #110000;
  --color-heading: #003399;
  --color-white: #ffffff;
  --color-sidebar: #455B90;
  --color-sidebar-hover: #FF9933;

  --font-heading: 'Georgia', serif;
  --font-body: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

  --font-size-base: 1rem;
  --font-size-h1: clamp(1.5rem, 4vw, 2.2rem);
  --font-size-h2: clamp(1.25rem, 3vw, 1.6rem);
  --font-size-h3: clamp(1.05rem, 2.5vw, 1.2rem);
  --font-size-small: 0.875rem;

  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2rem;
  --space-xl: 3rem;

  --sidebar-width: 220px;
  --header-height: 60px;
  --border-radius: 4px;
}

*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; }
html { scroll-behavior: smooth; }

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

img, picture, video, canvas, svg { display: block; max-width: 100%; }
input, button, textarea, select { font: inherit; }
p, h1, h2, h3, h4, h5, h6 { overflow-wrap: break-word; }

h1, h2, h3 {
  font-family: var(--font-heading);
  color: var(--color-heading);
  line-height: 1.2;
  margin-bottom: var(--space-sm);
}

h1 { font-size: var(--font-size-h1); }
h2 { font-size: var(--font-size-h2); margin-top: var(--space-lg); }
h3 { font-size: var(--font-size-h3); margin-top: var(--space-md); }

a { color: var(--color-link); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ===== LAYOUT: Header + Sidebar + Content + Footer ===== */

.page-wrapper {
  display: flex;
  min-height: 100vh;
  flex-direction: column;
}

/* Header — full width, minimal */
.site-header {
  background-color: var(--color-primary);
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-md);
  border-bottom: 3px solid var(--color-divider);
}

.site-header .logo {
  font-family: var(--font-heading);
  font-weight: bold;
  font-size: 1.3rem;
  color: var(--color-accent);
  text-decoration: none;
}

.site-header .logo:hover { text-decoration: none; }

.site-header .header-right {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

/* Hamburger — only on mobile */
.sidebar-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--color-white);
  font-size: 1.5rem;
  cursor: pointer;
  padding: 0.25rem;
}

/* Body row: sidebar + content */
.body-row {
  display: flex;
  flex: 1;
}

/* Sidebar — always visible on desktop */
.sidebar {
  width: var(--sidebar-width);
  min-width: var(--sidebar-width);
  background-color: var(--color-sidebar);
  padding: var(--space-md) 0;
  overflow-y: auto;
  border-right: 3px solid var(--color-divider);
}

.sidebar ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.sidebar ul li {
  border-bottom: 1px solid var(--color-divider);
}

.sidebar ul li a {
  display: block;
  padding: 0.5rem var(--space-md);
  color: var(--color-white);
  font-size: 0.9rem;
  text-decoration: none;
  transition: background-color 0.15s, color 0.15s;
}

.sidebar ul li a:hover {
  background-color: var(--color-divider);
  color: var(--color-accent);
  text-decoration: none;
}

.sidebar ul li a.sidebar-active {
  color: var(--color-accent);
  font-weight: bold;
}

/* Content area */
.content-area {
  flex: 1;
  padding: var(--space-lg);
  min-width: 0;
}

.content-area .prose {
  max-width: 80ch;
}

/* Footer — full width */
.site-footer {
  background-color: var(--color-primary);
  color: var(--color-secondary);
  padding: var(--space-sm) var(--space-md);
  text-align: right;
  font-size: 0.85rem;
  border-top: 3px solid var(--color-divider);
}

/* ===== Mobile: sidebar collapses to hamburger ===== */
@media (max-width: 768px) {
  .sidebar-toggle {
    display: block;
  }

  .body-row {
    position: relative;
  }

  .sidebar {
    display: none;
    position: fixed;
    top: var(--header-height);
    left: 0;
    bottom: 0;
    z-index: 999;
    box-shadow: 4px 0 12px rgba(0,0,0,0.3);
  }

  .sidebar.sidebar-open {
    display: block;
  }

  .sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    top: var(--header-height);
    background: rgba(0,0,0,0.4);
    z-index: 998;
  }

  .sidebar-overlay.sidebar-open {
    display: block;
  }

  .content-area {
    padding: var(--space-md);
  }
}

/* ===== Tables ===== */
.table-wrapper {
  overflow-x: auto;
  margin-block: var(--space-lg);
  border: 1px solid var(--color-secondary);
  border-radius: var(--border-radius);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}

th {
  background-color: var(--color-primary);
  color: var(--color-white);
  text-align: left;
  padding: var(--space-sm);
  font-family: var(--font-heading);
}

td {
  padding: var(--space-sm);
  border-bottom: 1px solid var(--color-secondary);
}

tr:nth-child(even) { background-color: var(--color-bg); }
tr:nth-child(odd) { background-color: var(--color-white); }

/* ===== Converter Tool ===== */
.date-input {
  margin-bottom: var(--space-lg);
}

.input-controls {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  flex-wrap: wrap;
  margin-top: var(--space-sm);
}

.input-controls select,
.input-controls input[type="number"] {
  padding: 0.4rem 0.6rem;
  border: 1px solid var(--color-secondary);
  border-radius: var(--border-radius);
  background: var(--color-white);
}

.input-controls input[type="number"] {
  width: 5rem;
}

.input-controls select {
  min-width: 8rem;
}

.current-date {
  margin-top: var(--space-xs);
  font-size: var(--font-size-small);
  color: var(--color-muted);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-md);
}

.card {
  background-color: var(--color-white);
  border: 1px solid var(--color-secondary);
  border-radius: var(--border-radius);
  padding: var(--space-md);
  box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.card h3 {
  margin-top: 0;
  font-size: 1rem;
  color: var(--color-primary);
}

.card .date-display {
  font-size: 1.1rem;
  font-weight: bold;
  color: var(--color-text);
}

.card .era {
  font-size: var(--font-size-small);
  color: var(--color-muted);
}

.info-panel {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--space-md);
  margin-top: var(--space-lg);
}

.info-card {
  background-color: var(--color-white);
  border: 1px solid var(--color-secondary);
  border-radius: var(--border-radius);
  padding: var(--space-md);
}

.info-card h3 {
  margin-top: 0;
  font-size: 1rem;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.4rem 1rem;
  border-radius: var(--border-radius);
  font-weight: 600;
  cursor: pointer;
  border: 2px solid transparent;
  font-size: 0.9rem;
  background-color: var(--color-accent);
  color: var(--color-white);
}

.btn:hover {
  background-color: #e68a2e;
  text-decoration: none;
}

/* Prev/Next navigation */
.prev-next {
  margin-top: var(--space-lg);
  padding-top: var(--space-sm);
  border-top: 1px solid var(--color-secondary);
  font-size: var(--font-size-small);
}

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