/* =============================================
   Learning Isn't Linear - Desmos Page
   ============================================= */

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    background: #f5f5f5;
    color: #333;
    line-height: 1.6;
}

/* ========== DARK HEADER (restored) ========== */
header {
    background: #222;
    padding: 8px 0;
}

nav {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    padding: 0 20px;
    flex-wrap: wrap;
    gap: 20px;
}

.logo-container img {
    height: 38px !important;
    width: auto !important;
}

nav a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
    white-space: nowrap;
}

nav a:hover {
    color: #0077cc;
}

/* Sticky footer */
html, body {
    height: 100%;
}

body {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

main {
    flex: 1;
}

/* Hero */
.hero {
    text-align: center;
    padding: 40px 20px 30px;
    background: white;
    border-bottom: 1px solid #eee;
}

.hero h1 {
    font-size: 42px;
    margin: 0 0 8px 0;
    color: #222;
}

.hero p {
    margin: 0;
    font-size: 18px;
    color: #666;
}

/* Big Demo Windows */
.repository-container {
    max-width: 1200px;
    margin: 40px auto;
    padding: 0 20px;
    display: flex;
    justify-content: center;
}

.demo-window {
    width: 100%;
    max-width: 1100px;
    background: white;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.06);
    border: 1px solid #e1e1e1;
    overflow: hidden;
}

.demo-window iframe {
    display: block;
    width: 100%;
    height: 520px;
    border: none;
}

/* Footer */
footer {
    background: #222;
    color: #888;
    text-align: center;
    padding: 25px 20px;
    margin-top: auto;
}

.footer-nav {
    margin-top: 12px;
    display: flex;
    justify-content: center;
    gap: 15px;
}

.footer-nav a {
    color: #aaa;
    text-decoration: none;
}

.footer-nav a:hover {
    color: #0077cc;
}