与类选择符相似，ID选择符也基于一个属性的值，但这个属性是ID属性。

Like the class, an ID selector is based on the value of an attribute, but in this case, it's the ID attribute.

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样式表把属性（可以控制的属性）和值（为这些属性选择的值）与样式选择符联系起来。

The style sheet attaches properties (attributes that you can control) and values (your choices for the attributes) to the style selectors.

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