initial

initial CSS关键字将属性的初始（或默认）值应用于元素。不应将初始值与浏览器样式表指定的值混淆。它可以应用于任何CSS属性。这包括CSS简写all，initial 可用于将所有CSS属性恢复到其初始状态。

注意：在继承的属性上，初始值可能是意外的。你应该考虑使用 inherit, unset，或revert (en-US) 关键字代替。

示例

<p>
  <span>This text is red.</span>
  <em>This text is in the initial color (typically black).</em>
  <span>This is red again.</span>
</p>

p {
  color: red;
}

em {
  color: initial;
}

Specification	Status	Comment
CSS Cascading and Inheritance Level 4 initial	Candidate Recommendation	No changes from Level 3.
CSS Cascading and Inheritance Level 3 initial	Recommendation	Initial definition.

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Use unset to set a property to its inherited value if it inherits, or to its initial value if not.
Use revert (en-US) to reset a property to the value established by the user-agent stylesheet (or by user styles, if any exist).
Use inherit to make an element's property the same as its parent.
The all property lets you reset all properties to their initial, inherited, reverted, or unset state at once.