1.<html>
2. <head>
3. <style>
4. .c1{background-color:red}
5. .c2{background-color:yellow}
6. </style>
7. </head>
8. <body>
9. <div class="c1 c2">
10. testCSS
11. <div>
12. </body>
13.</html>
1.<html>
2. <head>
3. <style>
4. .c1{background-color:red}
5. .c3{background-color:yellow}
6. </style>
7. </head>
8. <body>
9. <div class="c1 c2">
10. testCSS
11. <div>
12. </body>
13.</html>
