Progressive Enhancement for modern browser & Graceful Degradation for IE

For the 
```
html {
  min-height: 100%;
}
```
The background-image can't fill full page unless `min-height: 100%` for html. Reason is here <http://richard.milewski.org/archives/1014>

```
background-color: #fff;
```
is for the fucking IE

The `border-radius` and `box-shadow` only the unprefixed version is supported since Firefox 13.0.

references:
- <https://developer.mozilla.org/zh-CN/docs/CSS/border-radius>
- <https://developer.mozilla.org/en-US/docs/CSS/box-shadow>

Following change is for search box under IE. Because the box-shadow is unavailable and border is none, the search box can be found.

```
*border: 1px solid #999;
border: 1px solid #999\9;
```