好吧，我是新的HTML, CSS和Java，但我尝试了我的方式，这对我在所有浏览器。我使用JS而不是CSS，它不适用于一些浏览器。

首先，我给HR元素赋予id="myHR"，并在Java Script中使用。 以下是守则。

x = document.getElementById("myHR");
y = x.style.width = "600px";
y = x.style.color = "white";
y = x.style.height = "2px";
y = x.style.border = "none";
y = x.style.backgroundColor = "lightgrey";

你可以像这样添加引导bg类

<hr class="bg-light" />

hr {
  color: #f00;
  background-color: #f00;
  height: 5px;
}

hr {
  background-color: #123455;
}

背景是你应该尝试改变的。

你也可以使用边界的颜色。我不确定;我认为这存在跨浏览器的问题。您应该在不同的浏览器中测试它。

因为我没有声誉来评论，我将在这里给出一些想法。

如果你想要一个可变高度的CSS，去掉所有的边框，并给出一个背景色。

    hr{
        height:2px;
        border:0px;
        background:green;
        margin:0px;/*sometimes useful*/
    }
    /*Doesn't work in ie7 and below and in Quirks Mode*/

if you want simply a style that you know that will work (example: to replace a border in a ::before element for most email clients or hr{ height:0px; border:0px; border-top:2px solid blue; margin:0px;/*useful sometimes*/ } In both ways, if you set a width, it will always have it's size. No need to set display:block; for this. To be totally safe, you can mix both, 'cause some browsers can get confused with height:0px;: hr{ height:1px; border:0px; background:blue; border-top:1px solid blue; margin:0px;/*useful sometimes*/ } With this method you can be sure that it will have at least 2px in height. It's a line more, but safety is safety. This is the method you should use to be compatible with almost everything. Remember: Gmail only detects inline css and some email clients may not support backgrounds or borders. If one fails, you will still have a 1px line. Better than nothing. In the worst cases, you can try to add color:blue;. In the worst of the worst cases, you can try to use a <font color="blue"></font> tag and put your precious <hr/> tag inside it. It will inherit the <font></font> tag color. With this method, you WILL want to do like this: <hr width="50" align="left"/>. Example: <span> awhieugfrafgtgtfhjjygfjyjg <font color="#42B3E5"><hr width="50" align="left"/></font> </span> <!--Doesn't work in ie7 and below and in Quirks Mode--> Here is a link for you to check: http://jsfiddle.net/sna2D/

有些浏览器使用color属性，有些使用background-color属性。为了安全起见:

hr {
  color: #color;
  background-color: #color;
}