为什么cssrequirements p.p5会对第一段div#preamble照成影响？？？

Question

@charset "utf-8";/* CSS Document */body,div,h1,h2,h3,h4,ul,li,input,p,span{margin:0;padding:0;list-style:none;border:none;}body{background: #361212 url(../images/background.gif) repeat-x;font-size:0.75em;line-height:1.6em;color:#f6f5d9;}a:link,a:visited{color:#e9907e;text-decoration:none;}a:hover{color:#f6f5d9;text-decoration:underline;}/* container--------------------------------------------------------------------------------*/div#container{width:760px;background:#000 url(../images/background_header.gif) no-repeat top  center;margin: 0  auto;overflow:hidden;}/* intro--------------------------------------------------------------------------------*/div#intro{width:580px;float:left;}div#pageHeader,div#quickSummary p.p1{display:none;}div#quickSummary p.p2{width:270px;margin:222px 0 0 310px;}div#preamble{width:375px;background:url(../images/content_boxes_middle_preamble.gif) repeat-y top;margin-left:205px;}div#preamble h3{height:85px;background:url(../images/headline_preamble.gif) no-repeat;}div#preamble h3 span{display:none;}div#preamble p{padding:0 10px 10px 20px;}div#preamble p.p1{margin-top:-25px}div#preamble p.p3{background:url(../images/content_boxes_bottom_preamble.gif) no-repeat bottom;padding-bottom:68px;}div#explanation{width:560px;background:url(../images/content_boxes_middle.gif) repeat-y top;margin-left:28px;}div#explanation h3{height:85px;background:url(../images/headline_explanation.gif) no-repeat;}div#explanation h3 span{display:none;}div#explanation p{padding:0 10px 10px 20px;}div#explanation p.p1{margin-top:-25px;}div#explanation p.p2{background:url(../images/content_boxes_bottom.gif) no-repeat  bottom;background-size:560px;padding-bottom:68px;}div#participation{width:560px;background:url(../images/content_boxes_middle.gif) repeat-y top;margin-left:28px;}div#participation h3{height:85px;background:url(../images/headline_participation.gif) no-repeat;}div#participation h3 span{display:none;}div#participation p{padding:0 10px 10px 20px;}div#participation p.p1{margin-top:-25px;}div#participation p.p3{background:url(../images/content_boxes_bottom.gif) no-repeat  bottom;background-size:560px;padding-bottom:68px;}div#benefits{width:560px;background:url(../images/content_boxes_middle.gif) repeat-y top;margin-left:28px;}div#benefits h3{height:85px;background:url(../images/headline_benefits.gif) no-repeat;}div#benefits h3 span{display:none;}div#benefits p{padding:0 10px 10px 20px;}div#benefits p.p1{margin-top:-25px;}div#benefits p.p1{background:url(../images/content_boxes_bottom.gif) no-repeat  bottom;background-size:560px;padding-bottom:68px;}div#requirements{width:560px;background:url(file:///H|/2017Dream%20weaver/7/2017-5-12/%E4%B8%A4%E5%88%97%E5%B8%83%E5%B1%80/images/content_boxes_middle.gif)  top;margin-left:28px}div#requirements h3{height:85px;background:url(../images/headline_requirements.gif) no-repeat;}div#requirements h3 span{display:none;}div#requirements p{padding:0 10px 10px 20px;} div#requirements p.p1{margin-top:-25px;}div#requirements p.p5{background:url(../images/content_boxes_bottom.gif) no-repeat  bottom;background-size:560px;padding-bottom:68px;}*//* supportingText--------------------------------------------------------------------------------*/div#supportingText{width:580px;float:left;}/* linkList--------------------------------------------------------------------------------*/div#linkList{width:160px;float:left;}