body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: #ffffff;
    color: #222;
    line-height: 1.7;
}
header {
    background: #111827;
    color: white;
    padding: 30px;
    text-align: center;
}
nav {
    background: #f3f4f6;
    padding: 15px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    justify-content: center;
    border-bottom: 1px solid #ddd;
}
nav a {
    color: #111827;
    text-decoration: none;
    padding: 8px 12px;
    border-radius: 6px;
    background: #e5e7eb;
}
.container {
    display: flex;
    max-width: 1300px;
    margin: auto;
    padding: 20px;
    gap: 20px;
}
main {
    flex: 3;
}
aside {
    flex: 1;
}
.sidebar {
    position: sticky;
    top: 20px;
}
.card {
    border: 1px solid #ddd;
    border-radius: 10px;
    padding: 20px;
    margin-bottom: 20px;
}
.ad-slot {
    background: #f9fafb;
    border: 2px dashed #cbd5e1;
    padding: 30px;
    text-align: center;
    margin: 30px 0;
    border-radius: 10px;
}
footer {
    background: #111827;
    color: white;
    text-align: center;
    padding: 20px;
    margin-top: 40px;
}
h1, h2, h3 {
    color: #111827;
}
@media (max-width: 900px) {
    .container {
        flex-direction: column;
    }
}