article {
	color: green;
	font-size: 18px;
	padding-left: 12px;
	line-height:26px;
}

.blue_text {
	color: blue;
}

#monkey {
	color: purple;
}

h3, span{
	color: orange;
}
	
article h3{
	color: cyan;
}

<article>dog</article>

<article class="blue_text">cat</article>

<article class="blue_text" style="color: red;">mouse</article>

<article id="monkey" class="blue_text">monkey</article>

<article class="blue_text">
	<h3>horse</h3>
	<span>hawk</span>
	<div>
		<article>dolphin</article>
	</div>
</article>