/* Global styles */
body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background: #f4f4f4;
    color: #333;
}

/* Header */
.header {
    background-color: #0073aa;
    color: #fff;
    text-align: center;
    padding: 25px 0;
    border-radius: 8px 8px 0 0;
}
.header h1 {
    margin: 0;
    font-size: 2rem;
}
.header p {
    margin: 5px 0 0 0;
    font-size: 1.1rem;
}

/* Navigation as compact boxes/buttons */
.nav- horizontal {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 10px; /* space between boxes */
    padding: 15px 0;
    background-color: #f4f4f4;
}

.nav a {
    display: inline-block;  /* keeps width around text */
    flex: 0 0 auto;         /* prevents flex from stretching the box */
    padding: 10px 10px;     /* adjust for comfortable size */
    border-radius: 6px;
    background-color: #0073aa;
    color: #fff;
    font-weight: bold;
    text-align: center;
    text-decoration: none;
}

.nav a:hover {
    background-color: #005d87;
    transform: translateY(-2px);
}

/* Optional: highlight active page */
.nav a.active {
    background-color: #ff9900;
    color: #fff;
}
/* Main container and boxes */
.container {
    max-width: 1000px;
    margin: 18px auto;
    padding: 0 12px;
}
.box {
    background: #fff;
    padding: 18px;
    margin-bottom: 20px;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}
.box h2 {
    margin-top: 10;
    color: #0073aa;
}
.box ul {
    padding-left: 20px;
}
.box li {
    margin-bottom: 8px;
}
/* ===== Theme variables ===== */
:root {
  --bg: #ffffff;
  --text: #1a1a1a;
  --card: #f4f4f4;
  --border: #dddddd;
  --link: #0066cc;
}

body.dark {
  --bg: #0f172a;       /* dark blue/black */
  --text: #e5e7eb;
  --card: #1e293b;
  --border: #334155;
  --link: #38bdf8;
}

/* ===== Apply theme ===== */
body {
  background-color: var(--bg);
  color: var(--text);
  transition: background 0.3s, color 0.3s;
}

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

/* Boxes / cards */
.box, .card, nav a {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px;
}

/* Footer */
.footer {
    background-color: #222;
    color: #fff;
    text-align: center;
    padding: 15px 0;
    font-size: 0.9rem;
    border-radius: 0 0 8px 8px;
}
.footer a {
    color: #fff;
    text-decoration: none;
    margin: 0 8px;
}
.footer a:hover {
    text-decoration: underline;
}

/* Buttons inside lesson boxes */
.lesson-box a {
    display: inline-block;
    margin-top: 10px;
    text-decoration: none;
    color: #fff;
    background: #0073aa;
    padding: 8px 12px;
    border-radius: 8px;
    transition: background 0.2s;
}
.lesson-box a:hover {
    background: #005d87;
}

/* Responsive */
@media (max-width: 768px) {
    .nav {
        flex-direction: column;
    }
}