html – Margin-top不能使用

我试图轻轻地推送电子邮件标签,并通过向标签分配一个类“brtop”来输入一点.

.brtop只是增加了上限.

似乎没有做任何事情,我做错了什么？

/* html5doctor.com Reset v1.6.1 - http://cssreset.com */
html,body,div,span,object,iframe,h1,h2,h3,h4,h5,h6,p,blockquote,pre,abbr,address,cite,code,del,dfn,em,img,ins,kbd,q,samp,small,strong,sub,sup,var,b,i,dl,dt,dd,ol,ul,li,fieldset,form,label,legend,table,caption,tbody,tfoot,thead,tr,th,td,article,aside,canvas,details,figcaption,figure,footer,header,hgroup,menu,nav,section,summary,time,mark,audio,video{margin:0;padding:0;border:0;outline:0;font-size:100%;vertical-align:baseline;background:transparent}body{line-height:1}article,section{display:block}nav ul{list-style:none}blockquote,q{quotes:none}blockquote:before,blockquote:after,q:before,q:after{content:none}a{margin:0;padding:0;font-size:100%;vertical-align:baseline;background:transparent}ins{background-color:#ff9;color:#000;text-decoration:none}mark{background-color:#ff9;color:#000;font-style:italic;font-weight:bold}del{text-decoration:line-through}abbr[title],dfn[title]{border-bottom:1px dotted;cursor:help}table{border-collapse:collapse;border-spacing:0}hr{display:block;height:1px;border:0;border-top:1px solid #ccc;margin:1em 0;padding:0}input,select{vertical-align:middle}

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form{
	width:500px;
	padding:1.5em;
	overflow:hidden;
	border:1px solid red;
}
fieldset{
	float:left;
	border:none;
	margin-left:1em;
}

.brtop{
margin-top:5px;
}

input{
}

<form name="messageform">
		<fieldset>
			<label for="username" >Name:</label><br/>
			<input type="text" name="username"/><br/>
			<label for="email"class="brtop">Email:</label><br/>
			<input type="text" name="email"/>
		</fieldset>
		<fieldset>
			<label>Message:</label><br/>
			<textarea name="message" cols="20" rows="4"></textarea>
		</fieldset>		
	</form>

解决方法

添加显示：内嵌块到您的brtop规则.

.brtop {
    margin-top:5px;
    display:inline-block;
}

jsFiddle example

由于您的标签显示为内联元素,所以顶部边距不会有任何影响.

Margin properties specify the width of the margin area of a Box. The ‘margin’ shorthand property sets the margin for all four sides while the other margin properties only set their respective side. These properties apply to all elements,but vertical margins will not have any effect on non-replaced inline elements. – 07001