There is the solution if you need only outline without border. It's not mine. I got if from Bootstrap css file. If you specify outline: 1px auto certain_color, you'll get thin outer line around div of certain color. In this case the specified width has no matter, even if you specify 10 px width, anyway it will be thin line. The key word in mentioned rule is "auto". If you need outline with rounded corners and certain width, you may add css rule on border with needed width and same color. It makes outline thicker.

Chrome 94.0 +。

I tested it in chrome 94.0 and it seems that the outline property honors the border-radius now.

.outline { outline: 2px solid red; } .border { border: 2px solid red; } .outline-10 { border-radius: 10px; } .border-2 { border-radius: 2px; } .outline-2 { border-radius: 2px; } .border-10 { border-radius: 10px; } .outline-50 { border-radius: 50%; } .border-50 { border-radius: 50%; } .circle { display: inline-block; width:50px; height: 50px; } <strong>Test this in chrome 94.0+</strong> <br/><br/> border-radius: 2px <span class="outline outline-2">outline</span> <span class="border border-2">border</span> <br/><br/> border-radius: 10px <span class="outline outline-10">outline</span> <span class="border border-10">border</span> <br/><br/> border-radius: 50% <span class="outline outline-50">outline</span> <span class="border border-50">border</span> <span class="outline circle outline-50">outline</span> <span class="border circle border-50">border</span>

Firefox 88+: border-radius

从2021年4月起，你就可以在Firefox上使用简单的CSS了:

.actual { 轮廓:实红色; border - radius: 10 px; ｝ .expected { 边框:实红色; border - radius: 10 px; ｝ 在Firefox 88+中， <span class="actual">this outline</span> 应该是这样的 <span class="expected">this border</span>

Firefox 86.0的当前行为:

Webkit:没有解决方案

使用outline-style: auto将告诉«用户代理渲染自定义outline样式»:参见[MDN](https://developer.mozilla.org/en-US/docs/Web/CSS/outline-style(。

当您使用outline-style: auto时，基于webkit的浏览器将在边界上绘制轮廓。很难正确地设计它的风格。

.actual { 大纲:自动红色; border - radius: 10 px; ｝ .expected { 边框:实红色; border - radius: 10 px; ｝ 在WebKit浏览器(Chrome, Edge)中， <span class="actual">this outline</span> 应该看得很近 <span class="expected">this border</span>

Chrome 89.0的当前行为:

更多的信息

从Firefox 88(将于2021年4月20日发布)开始，outline将遵循边界半径的形状。 当前的-moz-outline-radius将变得多余并将被删除。

参见MDN关于-moz-outline-radius的条目:

从Firefox 88开始，标准的outline属性将遵循border-radius的形状，使-moz-outline-radius属性变得多余。因此，此属性将被删除。

No. Borders sit on the outside of the element and on the inside of the box-model margin area. Outlines sit on the inside of the element and the box-model padding area ignores it. It isn't intended for aesthetics. It's just to show the designer the outlines of the elements. In the early stages of developing an html document for example, a developer might need to quickly discern if they have put all of the skeletal divs in the correct place. Later on they may need to check if various buttons and forms are the correct number of pixels apart from each other.

边界本质上是审美的。与大纲不同，它们实际上是盒子模型的一部分，这意味着它们不会重叠设置为margin: 0的文本;边界的每一边都可以单独设置样式。

如果你试图应用一个角半径轮廓，我假设你使用它的方式大多数人使用边界。如果你不介意我问，outline的什么属性使它在边界上是可取的?

There is the solution if you need only outline without border. It's not mine. I got if from Bootstrap css file. If you specify outline: 1px auto certain_color, you'll get thin outer line around div of certain color. In this case the specified width has no matter, even if you specify 10 px width, anyway it will be thin line. The key word in mentioned rule is "auto". If you need outline with rounded corners and certain width, you may add css rule on border with needed width and same color. It makes outline thicker.

结合盒子阴影和轮廓。

李·海耶斯的回答有点小变化 我发现

input[type=text]:focus {
    box-shadow: 0 0 0 1pt red;
    outline-width: 1px;
    outline-color: red;
}

最后的效果非常干净。没有使用边界半径时的大小跳跃