There are differences between #header .callout
and #header.callout
in css.
Here is the "plain English" of #header .callout
:
Select all elements with the class name callout
that are descendants of the element with an ID of header
.
And #header.callout
means:
Select the element which has an ID of header
and also a class name of callout
.
You can read more here css tricks