Demo: CSS font-weight

<div class='container'>
    <h1 class='normal'>Normal Weight</h1>
    <h1 class='bold'>Bold Weight</h1>
    <h1 class='bolder'>Bolder Weight</h1>
</div>

.container {
    text-align: center;
    margin-top: 50px;
}

.normal {
    font-weight: normal;
    font-size: 24px;
}

.bold {
    font-weight: bold;
    font-size: 24px;
}

.bolder {
    font-weight: bolder;
    font-size: 24px;
}

// No JavaScript required for this demo