[ticket/12598] Improve search box styling

https://tracker.phpbb.com/browse/PHPBB3-12598

![newsearch](https://cloud.githubusercontent.com/assets/3015760/3170466/20e332d6-ebb8-11e3-9292-99e7dc54a809.png)
![newsearch](https://cloud.githubusercontent.com/assets/3015760/3375561/566e93fa-fbcb-11e3-8569-8a1ad125ef0e.png)
PHPBB3-12598
haha already have it the new tweaks file lol

````
/* Style Sheet Tweaks

These style definitions are IE 8 and 9 specific
tweaks required due to its poor CSS support.
-------------------------------------------------*/

/* 
    IE 8 Fixes 
*/

/* Clear float fix */
.inner { zoom: 1\9; }

ul.linklist { zoom: 1\9; }

/* Align checkboxes/radio buttons nicely */
dd label input { vertical-align: text-bottom\9; }

/* Fixes header-avatar aspect-ratio in IE8 */
.header-avatar img {
    height: 20px\9;
}

/* 
    IE 9 Fixes 
*/

/* IE8 often can't handle max-width in %, so we use px instead */
.postprofile .avatar img {
    max-width: 150px; 
}

/* Border-radius bleed fix in IE9 */
#search-box, #search-box .inputbox, #search-box a.button {
    border-radius: 0;
}
````