css a question_html/css_WEB-ITnose

I want them to be arranged in rows according to the size specified in .pic_upload. Logically speaking, the space should be a square. Why are they staggered?




.pic_upload
{
width:184;
height:184;
float:left;
margin:20px 0 0 20px;
border:2px solid #5FA9E1;
}

<div id="picload"><div class="pic_upload"><img src="/Pic/20131205/30424786-15b5-4ab2-a027-c898e7c21c01/m.jpg" alt=""></div><div class="pic_upload"><img src="/Pic/20131205/055642e6-b06f-4b09-8117-2840d0e677c4/m.jpg" alt=""></div><div class="pic_upload"><img src="/Pic/20131205/4c507710-3fa2-4fc5-ad5f-ca621dc3ed6b/m.jpg" alt=""></div><div class="pic_upload"><img src="/Pic/20131205/d7b56f62-b408-41ff-a635-668a048e2348/m.jpg" alt=""></div><div class="pic_upload"><img src="/Pic/20131205/d39c2238-f116-4c94-9ead-e203e35433b2/m.jpg" alt=""></div><div class="pic_upload"><img src="/Pic/20131205/f68d0b7b-e29d-4719-a003-8a3ec1871e6a/m.jpg" alt=""></div></div>

Reply to discussion (solution)

.pic_upload {     width:184px;     height:184px;     float:left;     margin:20px 0 0 20px;     border:2px solid #5FA9E1;  }

No unit added..