sample.md

HTML A

<div class="box">
    <div class="box-title"></div>
    <div class="box-content"></div>
</div>

CSS A

    .box {...}
    .box-title {...}
    .box-content {...}

HTML B

<div class="box">
    <h1></h1>
    <p></p>
</div>

CSS B

    .box {...}
    .box h1{...}
    .box p {...}

HTML C

<div class="box">
    <h1 class="box-title"></h1>
    <p class="box-content"></p>
</div>

CSS C

    .box {...}
    .box-title {...}
    .box-content {...}