Basic CSS: Adjust the Padding of an Element

<style>
.injected-text {
margin-bottom: -25px;
text-align: center;
}

.box {
border-style: solid;
border-color: black;
border-width: 5px;
text-align: center;
}

.yellow-box {
background-color: yellow;
padding: 10px;
}

.red-box {
background-color: crimson;
color: #fff;
padding: 20px;
}

.blue-box {
background-color: blue;
color: #fff;
padding: 10px;
}
</style>
<h5 class="injected-text">margin</h5>

<div class="box yellow-box">
<h5 class="box red-box">padding</h5>
<h5 class="box blue-box">padding</h5>
</div>