Shorthand properties are CSS properties that let you set the values of multiple other CSS properties simultaneously. Using a shorthand property, you can write more concise (and often more readable) style sheets, saving time and energy.
The CSS specification defines shorthand properties to group the definition of common properties acting on the same theme.
For instance, the CSS background property is a shorthand property that's able to define the values of background-color, background-image, background-repeat, and background-position.
Similarly, the most common font-related properties can be defined using the shorthand font, and the different margins around a box can be defined using the margin shorthand.
CSS provides a universal shorthand property, all, which applies its value to every property in the document. Its purpose is to change the properties' inheritance model to one of:
CSS provides four special universal property values for controlling inheritance. Every CSS property accepts these values.
Sets the property value applied to a selected element to be the same as that of its parent element. Effectively, this "turns on inheritance".
Sets the property value applied to a selected element to the initial value of that property.
Resets the property to its natural value, which means that if the property is naturally inherited it acts like inherit, otherwise it acts like initial.
For example:
body {
color: green;
}
.my-class-1 a {
color: inherit;
}
.my-class-2 a {
color: initial;
}
.my-class-3 a {
color: unset;
}
<ul>
<li>Default <a href="#">link</a> color</li>
<li class="my-class-1">Inherit the <a href="#">link</a> color</li>
<li class="my-class-2">Reset the <a href="#">link</a> color</li>
<li class="my-class-3">Unset the <a href="#">link</a> color</li>
</ul>
https://developer.mozilla.org/en-US/docs/Web/CSS/Shorthand_properties