(编辑:jimmy 日期: 2024/12/24 浏览:2)
**1、margin塌陷**
问题:垂直方向的父子关系的盒子使用不当会产生margin塌陷。给子级设置margin-top时,他不会相对父级一起动,只有他的margin超过父级的margin时,才会生效,但会带着父级一起动(作者总结,官方定义自己查看)。如:
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <div> <div>//20pxmargin-top </div> </div> </body> </html>
效果:
**解决方法:**
(1)给父级盒子加上边框border:1px silod black;(改变结构了,不推荐使用)
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <div> <div> </div> </div> </body> </html>
效果:
(2)触发盒子的BFC模型(不懂就去百度吧)
如何触发盒子的BFC呢?
1.Position:absolute; 2.display:inline-block; 3.float:left/right; 4.overflow:hiddle; 1.Position:absolute;给父级加上绝对定位,让子级相对父级动。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <div> <div> </div> </div> </body> </html>
效果:
2.display:inline-block;让父级同时具有行级属性和块级属性。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <div> <div> </div> </div> </body> </html>
效果:
3.float:left/right;让父级产生浮动流
``` <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <div> <div> </div> </div> </body> </html> ```
效果:
4.overflow:hiddle;溢出部分隐藏
``` <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <div> <div> </div> </div> </body> </html> ```
效果:
**2、margin合并**
问题:
margin-left和margin-right区域不能共用。只会叠加。
``` <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <span>1</span> <span>2</span> </body> </html> ```
效果:
两个兄弟结构垂直方向的margin共用。
``` <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <span>1</span> <span>2</span> <div>3</div> <div>3</div> </body> </html> ```
效果:
解决垂直方向的margin合并问题也是触动盒子的BFC。
解决方法如下:(嵌套盒子:然后:overflower:hidden;)
``` <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <span>1</span> <span>2</span> <div> <div>3</div> </div> <div>3</div></body></html>```
效果:
**总结:**
在实际开发时不解决这个问题,比如说要解决垂直方面200px,为什么不直接top200px呢,不用top100px,然后bottom100px。
**顺带说一下清除浮动的两种两种方法:**
(1)在有浮动的元素的后面加入一个标签。
下面我就简单举例了:
<div class = "clear"></div>
css中:
.clrar{clear:both;}
(2)使用伪类元素,找到需要清除的标签,直接使用三件套:
.warpper::after{ content:""; clrar:both; display:block; }
总结
以上所述是小编给大家介绍的解决margin塌陷与margin合并(margin)清除浮动问题,希望对大家有所帮助,如果大家有任何疑问欢迎给我留言,小编会及时回复大家的!