See: w3c: 6 Assigning property values, Cascading, and Inheritance – 6.2 Inheritance
An inherited value takes effect for an element only if no other style declaration has been applied directly to the element.
This style applies to an element with id="my_id"
:
#my_id {
color: red;
}
… and will apply (inherit) to an element nested within having class="my_class"
only if its color
property is otherwise unspecified.
…which no longer is the case once you declare:
.my_class {
color: blue;
}