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

body{
    font-family: Arial, Helvetica, sans-serif;
    background-color: #f4f6f9;
    color: #333;
    line-height: 1.8;
}

header{
    background: #1e3a8a;
    color: white;
    text-align: center;
    padding: 40px 20px;
}

header h1{
    margin-bottom: 10px;
}

nav{
    background: #2563eb;
    padding: 15px;
    text-align: center;
    position: sticky;
    top: 0;
    z-index: 100;
}

nav a{
    color: white;
    text-decoration: none;
    margin: 0 12px;
    font-weight: bold;
    transition: 0.3s;
}

nav a:hover{
    color: yellow;
}

main{
    width: 85%;
    max-width: 1100px;
    margin: 30px auto;
}

section{
    background: white;
    margin-bottom: 25px;
    padding: 25px;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

section h2{
    color: #1e3a8a;
    margin-bottom: 15px;
}

section h3{
    color: #2563eb;
    margin-top: 15px;
    margin-bottom: 10px;
}

.code{
    background: #272822;
    color: #f8f8f2;
    padding: 15px;
    border-radius: 5px;
    margin: 15px 0;
    font-family: Consolas, monospace;
    overflow-x: auto;
}

ul{
    margin-left: 25px;
}

ul li{
    margin-bottom: 8px;
}

ol{
    margin-left: 25px;
}

ol li{
    margin-bottom: 10px;
}

footer{
    background: #1e3a8a;
    color: white;
    text-align: center;
    padding: 15px;
    margin-top: 20px;
}

/* Responsive */

@media (max-width: 768px){

    nav a{
        display: block;
        margin: 10px 0;
    }

    main{
        width: 95%;
    }

    header h1{
        font-size: 24px;
    }
}