* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    }

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #0d0d0d;
    color: #f2f2f2;
    line-height: 1.6;
    padding: 50px;
}

h1, h2, h3, h4 {
    color: #00aaff;
    margin-bottom: 10px;
}

a {
    color: #00c8ff;
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

section {
    margin-bottom: 40px;
    background-color: #1a1a1a;
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 0 10px rgba(0, 170, 255, 0.1);
}

ul {
    list-style-type: square;
    padding-left: 20px;
}

li {
    margin-bottom: 10px;
}

img, iframe {
    max-width: 100%;
    height: auto;
    border-radius: 10px;
    margin: 15px 0;
}

footer {
    margin-top: 60px;
    text-align: center;
    color: #999;
    font-size: 0.9rem;
    border-top: 1px solid #222;
    padding-top: 20px;
}

.back-to-top {
    display: inline-block;
    margin-top: 10px;
    padding: 10px 20px;
    background-color: #00aaff;
    color: #fff;
    border-radius: 8px;
    transition: background 0.3s ease;
}

.back-to-top:hover {
    background-color: #0077aa;
}

.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 20px;
}

h2::before {
    content: "🧠 ";
}

h3::before {
    content: "🔹 ";
}