1 CSS Common sense

1 naming

I recommend using a completely lowercase class name and ID, with multiple words – to connect. For example: Andy-budd is much clearer than Andybudd.

2 ID and Class selector

ID Selector Format:

{    text-align:Center;     color:red;}

Class selector:

{    text-align:center;}

3 DTD and DOCTYPE

DTD: Document type definition, which defines what is allowed in a particular version of HTML, does not allow the browser to check the validity of the page through these rules. is a set of machine-readable rules.

DOCTYPE: Declares which DTD to use, and the browser knows which HTML version to use.

Dtd:document type definition, which defines what is allowed in a particular version of HTML, does not allow the browser to check the validity of the page through these rules. is a set of machine-readable rules.

DOCTYPE: Declares which DTD to use, and the browser knows which HTML version to use.

and promiscuous mode corresponds to the standard mode.

4 Common selectors

Element selector: p {}

Descendant selector: div p {}

ID selector: #demo {}

Class selector:. Demo {}

With these four kinds of selectors you can locate many and many elements.

1 CSS Common sense