SOURCE

<div class="m-demo">
	<p>文字颜色：color:red;</p>
	<p class="p1">文字颜色：color:#ff0000;</p>
	<p class="p2">文字颜色：color:rgb(255,0,0);</p>
	<p class="p3">文字颜色：color:rgba(255,0,0,1);</p>
	<p class="p4">文字颜色：color:rgba(255,0,0,0.5);</p>
</div>

p{margin:10px;background:#ddd;}
p+p{margin-left:40px;}

.m-demo{color:red;}
.m-demo .p1{color:#ff0000;}
.m-demo .p2{color:rgb(255,0,0);}
.m-demo .p3{color:rgba(255,0,0,1);}
.m-demo .p4{color:rgba(255,0,0,0.5);}