CSS Properties

Selectors and Declarations can be grouped

h1 ,  h2 ,  h3 { color: red  ;  text-align: center }

Selectors separated by commas
Declarations separated by semicolons
User agent must ignore a declaration with invalid property name or invalid value
```
h1 { colour: red ; text-align: center ; font-size:12 pt; 
    border:solid red 3}
```
- Colour ignored, mispelt!
- font-size ignored: no space allowed between value and units
- Complete border declaration ignored: no unit specified for border width

Style sheets can contain comments; they start with /* and finish with */

h1 {font-size:16pt}
p {color:green}

                  /* This is a CSS comment */
h2 {text-align:center; font-size:18pt}
/* It can span
several lines 
but they cannot be nested */
h3 {color:red;} /* Note they can be on the same line as a rule */
h4 {color:blue}