CSS优先级

id & class in CSS is case sensitive!!! id & class in CSS is case sensitive!!!
body font color was overridden by：

<style>  body {    background-color: black;    font-family: Monospace;    color: green;  }

class declarations

.pink-text {    color: pink !important；  }

subsequent class declarations

  .blue-text {    color: blue;  }

id declarations

  #orange-text {    color: orange;  }  </style>

In-line styles.

<h1 id="orange-text" class="pink-text blue-text" style="color: white">Hello World!</h1>

!important

comment out(HTML):

<!--    -->

comment out(CSS):

/**/