#top{width:100%;?overflow:hidden;border-bottom:1px solid #dadad9;background:#fff;?float:left;?【任務(wù)2】position：fixed;margin-top:0;margin-left:0;?text-align:center;}#top input{border:none;}.left{float:left; margin-left:10px;}.search{float:left; margin-left:10px; margin-top:7px;}.select_btn{background:url(images/select_top.gif) no-repeat; width:57px; height:42px; cursor:pointer; float:left;}.search_input{background:url(images/input_search.gif) no-repeat; width:104px; height:28px; float:left; padding-left:5px;}.search_btn{background:url(images/search_btn.gif) no-repeat; width:29px; height:28px; float:left;}.right{float:right; margin-right:10px; padding:5px 10px 0; border-left:1px solid #f5f5f5; border-right:1px solid #f5f5f5; height:37px;}.topbtn{background:url(images/top_btn.gif) no-repeat; width:54px; height:30px; line-height:30px; color:#444;}.margin_l_10{margin-left:10px;}.margin_t_5{margin-top:5px;}.center{margin:0 15px;}.center_r{margin-right:15px;}#mainbody{width:80%;?overflow:hidden;?【任務(wù)2】margin:0 auto;【任務(wù)3】padding:63px;}.content{width:236px; border:1px solid #dcdcda; float:left;}.content li{margin-bottom:15px; text-align:center;}.content li h2{text-align:left; padding:12px 15px; font-weight:normal; color:#444; background:#fff; margin-top:-3px; background:#fafafa;}.content li dl{border-top:1px solid #f2f2f2; text-align:left;}.content li dt{padding:15px; float:left; border-right:1px solid #f2f2f2;}.content li dd{padding-top:18px; text-indent:15px;}.content li dd a{color:#9e7e6b;}#footer{width:100%; background:#fff; text-align:center; padding:20px 0; color:#999; border-top:#ccc; margin-top:20px;}</style></head><body><div id="top">? <div class="left">? ? <div class="select_btn"></div>? ? <div class="search">? ? ? <input type="text" class="search_input" />? ? ? <input type="button" class="search_btn" />? ? </div>? </div>??<div class="right">? ? <input type="button" value="登錄" class="topbtn" />? ? <input type="button" value="注冊(cè)" class="topbtn margin_l_10" />? </div></div><div id="mainbody">? <div class="content">當(dāng)我任務(wù)2中寫 margin-left 時(shí)，任務(wù)3 寫margin時(shí)無法實(shí)現(xiàn) mainbody 下移，只能通過padding:63px.而寫left、top 時(shí)，任務(wù)3就可以用margin下移。請(qǐng)問這兩種情況怎么理解呢
請(qǐng)問margin-left 和left為什么影響不同，怎么理解呢
qq_電波_03505597
2016-06-21 23:54:24