1. img元素与下面临近的元素中间会有10px左右的间隔，要去除间隔需要diaplay:block
<img class="vac_ad_default" src="http://pic.c-ctrip.com/h5/group_travel/top_banner.jpg" style="display:block;width:100%"/> <div>asdfasdfasdfasdfsdafasdfasd</div>
