我有以下html和css代码：
<!DOCTYPE HTML>
<html>
<head>
</head>
<body>
<div class="wrapper">
<header>
<section class="top">
<div id="quote"><a href="contact.html"><p>Request a quote</p></a></div>
<div class="arrow"><img src="icons/top-icon.png" alt=""></div>
</section>
</body>
</html>
a {
font-size: 1.6em;
color: #fff;
text-decoration: none;
}
.top {
height: 3.2em;
width: 100%;
background: rgb(255,214,94); /* Old browsers */
background: -moz-linear-gradient(top, rgba(255,214,94,1) 0%, rgba(254,191,4,1) 100%); /* FF3.6+ */
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(255,214,94,1)), color-stop(100%,rgba(254,191,4,1))); /* Chrome,Safari4+ */
background: -webkit-linear-gradient(top, rgba(255,214,94,1) 0%,rgba(254,191,4,1) 100%); /* Chrome10+,Safari5.1+ */
background: -o-linear-gradient(top, rgba(255,214,94,1) 0%,rgba(254,191,4,1) 100%); /* Opera 11.10+ */
background: -ms-linear-gradient(top, rgba(255,214,94,1) 0%,rgba(254,191,4,1) 100%); /* IE10+ */
background: linear-gradient(top, rgba(255,214,94,1) 0%,rgba(254,191,4,1) 100%); /* W3C */
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#ffd65e', endColorstr='#febf04',GradientType=0 ); /* IE6-9 */
position: fixed;
top: 0;
left :0;
z-index: 10;
text-align: center;
border-bottom: 1px solid #f9e555;
-webkit-box-shadow: 0px 0px 8px #555;
-moz-box-shadow: 0px 0px 8px #555;
box-shadow: 0px 0px 8px #555;
}
.top div#quote {
width: 20em;
background: rgb(254,252,234); /* Old browsers */
background: -moz-linear-gradient(top, rgba(254,252,234,1) 0%, rgba(241,218,54,1) 100%); /* FF3.6+ */
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(254,252,234,1)), color-stop(100%,rgba(241,218,54,1))); /* Chrome,Safari4+ */
background: -webkit-linear-gradient(top, rgba(254,252,234,1) 0%,rgba(241,218,54,1) 100%); /* Chrome10+,Safari5.1+ */
background: -o-linear-gradient(top, rgba(254,252,234,1) 0%,rgba(241,218,54,1) 100%); /* Opera 11.10+ */
background: -ms-linear-gradient(top, rgba(254,252,234,1) 0%,rgba(241,218,54,1) 100%); /* IE10+ */
background: linear-gradient(top, rgba(254,252,234,1) 0%,rgba(241,218,54,1) 100%); /* W3C */
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#fefcea', endColorstr='#f1da36',GradientType=0 ); /* IE6-9 */
margin: 0 auto;
}
.top div#quote p {
color: #f2572a;
height: 3.5em;
font-size: 1.5em;
padding: 0;
margin: 0;
}
.top div#quote a {
font-size: 1.1em;
}
.top div#quote p:hover {
color: #ed3419;
}
.arrow {
display: inline-block;
margin: 0 auto;
border: 1px solid #000;
position: relative;
}
这里有两个问题：第一个问题是＆＃34;请求报价div＆＃34;大于css中定义的3.2em，第二个是如果我删除文本结构：中心.top样式，引号div下面的图像将不会保持居中。我试图将相对的.arrow div和绝对位置定位为img图标，但是当div完全消失时它不起作用。还有其他想法吗？
答案 0 :(得分：7)
由于.arrow元素的默认宽度为100％，因此设置margin: 0 auto水平无效。由于img是一个内联元素，因此它也不会起作用。您需要在.arrow元素上设置显式宽度，或在display: block元素上设置margin: 0 auto和img。
答案 1 :(得分：2)
“请求引用”div更大，因为它的高度与其字体大小有关。 em基于字母M的当前宽度（至少在classic typography中）。由于您更改了font-size中3.2em元素中的.top与3.2em中的.top div#quote p不同。
即使您不更改font-size值仍然不同（3.2em中的.top，3.5em中的.top div#quote p。
您应该删除所有padding-top，padding-bottom，margin-top和margin-bottom，而只需使用height:100%。
<div class="wrapper">
<header>
<section class="top">
<p class="quote"><a href="contact.html">Request a quote</a></p>
<img class="arrow" src="icons/top-icon.png" alt="Arrow"></div>
</section>
</header>
</div>
a {
color: #fff;
text-decoration: none;
}
.top {
position: fixed;
top: 0;
left: 0;
right: 0;
z-index: 10;
height: 3.2em;
background: rgb(255,214,94); /* Old browsers */
background: linear-gradient(top, rgba(255,214,94,1) 0%,rgba(254,191,4,1) 100%); /* W3C */
text-align: center;
border-bottom: 1px solid #f9e555;
box-shadow: 0px 0px 8px #555;
}
.top p.quote {
width: 20em;
height:100%;
padding: 0;
margin: 0 auto;
color: #f2572a;
font-size: 1.6em;
line-height:2.1em;
background: rgb(254,252,234); /* Old browsers */
background: linear-gradient(top, rgba(254,252,234,1) 0%,rgba(241,218,54,1) 100%); /* W3C */
}
.top p.quote a{
color: #f2572a;
}
.top p.quote a:hover{
color: #ed3419;
}
.arrow {
display: inline-block;
margin: 0 auto;
border: 1px solid #000;
position: relative;
}
/* gradient and other vendor specific quirks */
.top{
/* background rules */
background: -moz-linear-gradient(top, rgba(255,214,94,1) 0%, rgba(254,191,4,1) 100%); /* FF3.6+ */
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(255,214,94,1)), color-stop(100%,rgba(254,191,4,1))); /* Chrome,Safari4+ */
background: -webkit-linear-gradient(top, rgba(255,214,94,1) 0%,rgba(254,191,4,1) 100%); /* Chrome10+,Safari5.1+ */
background: -o-linear-gradient(top, rgba(255,214,94,1) 0%,rgba(254,191,4,1) 100%); /* Opera 11.10+ */
background: -ms-linear-gradient(top, rgba(255,214,94,1) 0%,rgba(254,191,4,1) 100%); /* IE10+ */
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#ffd65e', endColorstr='#febf04',GradientType=0 ); /* IE6-9 */
/* vendor specific box shadows */
-webkit-box-shadow: 0px 0px 8px #555;
-moz-box-shadow: 0px 0px 8px #555;
}
.top p.quote{
background: -moz-linear-gradient(top, rgba(254,252,234,1) 0%, rgba(241,218,54,1) 100%); /* FF3.6+ */
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(254,252,234,1)), color-stop(100%,rgba(241,218,54,1))); /* Chrome,Safari4+ */
background: -webkit-linear-gradient(top, rgba(254,252,234,1) 0%,rgba(241,218,54,1) 100%); /* Chrome10+,Safari5.1+ */
background: -o-linear-gradient(top, rgba(254,252,234,1) 0%,rgba(241,218,54,1) 100%); /* Opera 11.10+ */
background: -ms-linear-gradient(top, rgba(254,252,234,1) 0%,rgba(241,218,54,1) 100%); /* IE10+ */
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#fefcea', endColorstr='#f1da36',GradientType=0 ); /* IE6-9 */
}