Compatible method with minimum height

In our normal project development, the minimum height can be directly used min-height!
If compatibility is considered, iE6 is not compatible. IE6 resolves the height to the minimum height by default. If both height and min-height appear, IE6 executes the height fixed height!
So how do we set it up: The
first method: min-height: 300px; _height: 300px;

The second method: min-height: 300px; height: auto! Important; height: 300px;

    a: 高版本浏览器解析顺序：
            min-height能识别，也能识别！important 
            并且height:auto;权重最高
            所以height:auto 就能把后写的height:300px覆盖。
    b:IE6解析流程：
            min-height不能识别，也不能识别！important  后写的height:300px;能把height:auto覆盖