1、z-index
2、margin的负值:margin-top:-20px;
1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>margin的负值</title> 6 <style> 7 body{ 8 margin:0; 9 } 10 .c1{ 11 width: 200px; 12 height:200px; 13 background-color: red; 14 } 15 .c2{ 16 width:300px; 17 height:300px; 18 background-color: green; 19 margin-top:-20px; 20 } 21 </style> 22 </head> 23 <body> 24 25 26 27 28 <div class="c1"></div> 29 <div class="c2"></div> 30 31 32 </body> 33 </html>
3、外边距的注意事项:
margin-bottom:100px; margin-top:50px;取最大px的；
1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>外边距注意事项</title> 6 <style> 7 body{ 8 margin:0; 9 } 10 .c1{ 11 width:100%; 12 height:100px; 13 background-color: red; 14 margin-bottom:100px; 15 16 } 17 .c2{ 18 width:100%; 19 height:400px; 20 background-color:green; 21 margin-top:50px; 22 } 23 </style> 24 </head> 25 <body> 26 27 <div class="c1"></div> 28 <div class="c2"></div> 29 30 </body> 31 </html>