如何保持div包含在视口中，同时保持宽高比

问题描述

存在一个方形的div，它是一个任意百分比宽度（和相同的高度），需要与窗口缩放。

它必须在边界内的视口（即：不剪切外部）并保持其正方形形状 - 本质上重复了CSS的 c>，然后给div一个填充顶部100％，因此推动div的底部下来工作。如果你把它改成，例如 padding-top：56.25％; 它将给出一个16：9的比率。填充不会干扰div的内容，因为：之后只插入：在此元素内将受到影响。在这种情况下，没有任何元素使用：之后，因为你总是使用一个新的div的效果。

已编辑

：

DEMO

停止扩展超出点设置 max-width 和 max-height

  .wrapper {
 width：50％; 
 display：inline-block; 
 position：relative; 
 max-height：350px; 
 max-width：350px; 
} 
  

There exists a square div that is an arbitrary percent wide (and the same amount high) that needs to scale with the window.

It must stay within the bounds of the viewport (ie: not clipping outside) and maintain its square shape - essentially duplicating the background-size: contain; feature of CSS.

I need to support iOS Safari v3.2, so I can't use vw/vh/vmin/vmax and would strongly prefer a CSS-only solution.

解决方案

You can set it using :after in CSS

DEMO http://jsfiddle.net/kevinPHPkevin/5tzk3/307/

.wrapper:after {
    padding-top: 100%; /*Sets ratio*/
    display: block;
    content: '';
}

Explanation:

This works by inserting no content :after and then giving the div a padding top of 100%, thus pushing the bottom of the div down. If you change it to, say, padding-top: 56.25%; it would give a 16:9 ratio. The padding does not interfere with the content of the div as it is inserted :after and only elements that are associated with :after within this element would be affected. In this case there are no elements that use :after as you'd always use a new div for this effect.

Edited

DEMO http://jsfiddle.net/kevinPHPkevin/5tzk3/309/

to stop it expanding beyond a point set a max-width and max-height

.wrapper {
    width: 50%;
    display: inline-block;
    position: relative;
    max-height:350px;
    max-width:350px;
}

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