例子：
<h1 style="color:white" id="orange-text" class="pink-text blue-text" style="color: white">Hello World!</h1>
注解：Yay! We just proved that in-line styles will override all the CSS declarations in your style element.也就是说：Hello World!的颜色是白色。
但是有一个符号 !important;
.pink-text {
color: pink !important;
}
注解：Your pink-text class declaration should have the !important keyword to override all other declarations。
三种颜色的表示方式：英文(red)，十六进制(#FF0000/#F00)，RGB(255，0，0)；
Then:
Use Responsive Design with Bootstrap Fluid Containers：
Bootstrap will figure out how wide your screen is and respond by resizing your HTML elements - hence the name Responsive Design.
You can add Bootstrap to any app by adding the following code to the top of your HTML:
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.1/css/bootstrap.min.css"/>
In this case, we've already added it for you to this page behind the scenes.
