<button class="btn btn-xs">Кнопка маленькая</button>
<button class="btn btn-lg">Кнопка большая</button>
.btn {
   padding:1em;
   border-radius:1em;
   background-color: #ccc;
   border: 1px solid #ccc;
   text-transform:uppercase;
}
.btn-xs {
   font-size:14px;
}
.btn-lg {
   font-size:20px;
}

External CSS

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External JavaScript

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