* {
    box-sizing: border-box;
}

body {
    font-family: Arial, Helvetica, sans-serif;
    background-color: #f4f6f8;
    margin: 0;
    padding: 0;
    line-height: 1.6;
}

.container {
    max-width: 900px;
    margin: auto;
    background: #ffffff;
    padding: 30px;
}

/* HEADER */
header {
    text-align: center;
    border-bottom: 3px solid #2c3e50;
    margin-bottom: 30px;
}

header h1 {
    margin: 0;
    color: #2c3e50;
    font-size: 2.2rem;
}

header h2 {
    margin-top: 5px;
    color: #555;
    font-size: 1.2rem;
}

/* SECTIONS */
section {
    margin-bottom: 30px;
}

h3 {
    color: #2c3e50;
    border-left: 5px solid #3498db;
    padding-left: 10px;
    font-size: 1.3rem;
}

/* LISTS */
ul, ol {
    margin-left: 25px;
}

/* CODE BLOCK */
.code-block {
    background: #1e1e1e;
    color: #f8f8f2;
    padding: 15px;
    border-radius: 5px;
    overflow-x: auto;
    margin: 15px 0;
    font-size: 0.95rem;
}

/* FOOTER */
footer {
    text-align: center;
    font-weight: bold;
    padding-top: 20px;
    border-top: 2px solid #ddd;
}

/* MOBILE STYLES */
@media (max-width: 768px) {

    .container {
        padding: 20px;
    }

    header h1 {
        font-size: 1.8rem;
    }

    header h2 {
        font-size: 1rem;
    }

    h3 {
        font-size: 1.1rem;
    }

    ul, ol {
        margin-left: 15px;
    }

    .code-block {
        font-size: 0.85rem;
    }
}

/* EXTRA SMALL SCREENS LIKE CELL PHONE */
@media (max-width: 480px) {

    header h1 {
        font-size: 1.5rem;
    }

    header h2 {
        font-size: 0.95rem;
    }

    body {
        font-size: 0.95rem;
    }
}