Every CSS declaration includes a property / value pair. Depending on the property, the value can include a single integer or keyword, to a series of keywords and values with or without units. There are a common set of data types — values and units — that CSS properties accept. Below is an overview of most of these data types. Refer to the page for each value type for more detailed information.... Textual data types <custom-ident> Pre-defined keywords...specifications as <ident> or <custom-ident> , must be unquoted....