带边框的正方形 div。只显示角落

Question

我在我的网站上使用了一个播放器。
我想更改播放按钮的外观。

我想用虚线边框来做到这一点，然后增加虚线之间的 space。那没有用。

我无法使用图像。有CSS(3)解决方案吗？

我希望它看起来像这样。

真的都是拐角处！

------------更新----------------

所以我使用@Naila 的解决方案使它起作用。运行针对以下问题：

我为 WordPress 使用 Video.js 插件，我正在创建一个新皮肤

当我关注 css 时，我发现已经有一个 ::before-pseudo 可以处理播放箭头。

箭头的 ::before-pseudo 表示宽度为 100%，这有助于箭头位于中心。因为我使用 30% 的宽度使边框成为一个角。这会覆盖之前的 100% 宽度。结果如下：

这里是：
CodePen

如果您刚刚在 CSS 字段中通过此 CSS，您将到达我现在所在的位置并看到问题：

/*
Player Skin Designer for Video.js
http://videojs.com

To customize the player skin edit 
the CSS below. Click "details" 
below to add comments or questions.
This file uses some SCSS. Learn more  
at http://sass-lang.com/guide)

This designer can be linked to at:
http://codepen.io/heff/pen/EarCt/left/?editors=010
*/

// The following are SCSS variables to automate some of the values.
// But don't feel limited by them. Change/replace whatever you want. 

// The color of icons, text, and the big play button border.
// Try changing to #0f0
$primary-foreground-color: #fff; // #fff default
// The default color of control backgrounds is mostly black but with a little
// bit of blue so it can still be seen on all-black video frames, which are c ommon.
// Try changing to #900
$primary-background-color: #2B333F;  // #2B333F default

// Try changing to true
$center-big-play-button: true; // true default

.video-js {
 /* The base font size controls the size of everything, not just text.
 All dimensions use em-based sizes so that the scale along with the font size.
 Try increasing it to 15px and see what happens. */
 font-size: 10px;

 /* The main font color changes the ICON COLORS as well as the text */
 color: $primary-foreground-color;
}

/* The "Big Play Button" is the play button that shows before the video plays.
To center it set the align values to center and middle. The typical location
of the button is the center, but there is trend towards moving it to a corner
where it gets out of the way of valuable content in the poster image.*/
.vjs-default-skin .vjs-big-play-button {
  /* The font size is what makes the big play button...big. 
 All width/height values use ems, which are a multiple of the font size.
 If the .video-js font-size is 10px, then 3em equals 30px.*/
 font-size: 3em;

 /* We're using SCSS vars here because the values are used in multiple places.
 Now that font size is set, the following em values will be a multiple of the
 new font size. If the font-size is 3em (30px), then setting any of
 the following values to 3em would equal 30px. 3 * font-size. */
 $big-play-width: 3em; 
  /* 1.5em = 45px default */
  $big-play-height: 3em;

 line-height: $big-play-height;
 height: $big-play-height;
 width: $big-play-width;

 /* 0.06666em = 2px default */
 /* 0.3em = 9px default */
 border:none;
 border-radius:0;

 @if $center-big-play-button {
 /* Align center */
left: 50%;
top: 50%;
margin-left: -($big-play-width / 2);
margin-top: -($big-play-height / 2);   
} @else {
/* Align top left. 0.5em = 15px default */
left: 0.5em;
top: 0.5em;
}
}
.vjs-big-play-button:before {
 position: absolute;
content: "";
width: 30px !important;
height: 30px!important;
right: -2px;
bottom: -2px;
 border-left: 2px solid $primary-foreground-color;
border-top: 2px solid $primary-foreground-color;
}
.vjs-big-play-button:after {
 position: absolute;
 content: "";
 width: 30px;
 height: 30px;
 right: -2px;
 bottom: -2px;
 border-right: 2px solid $primary-foreground-color;
 border-bottom: 2px solid $primary-foreground-color;
}

/* The default color of control backgrounds is mostly black but with a little
  bit of blue so it can still be seen on all-black video frames, which are     common. */
.video-js .vjs-control-bar,
.video-js .vjs-big-play-button,
.video-js .vjs-menu-button .vjs-menu-content {
  /* IE8 - has no alpha support */
  background-color: $primary-background-color;
  /* Opacity: 1.0 = 100%, 0.0 = 0% */
  background-color: rgba($primary-background-color, 0.7);
}

// Make a slightly lighter version of the main background
// for the slider background.
$slider-bg-color: lighten($primary-background-color, 33%);

/* Slider - used for Volume bar and Progress bar */
.video-js .vjs-slider {
 background-color: $slider-bg-color;
 background-color: rgba($slider-bg-color, 0.5);
}

/* The slider bar color is used for the progress bar and the volume bar
(the first two can be removed after a fix that's coming) */
.video-js .vjs-volume-level,
.video-js .vjs-play-progress,
.video-js .vjs-slider-bar {
background: $primary-foreground-color;
}

/* The main progress bar also has a bar that shows how much has been loaded.     */
.video-js .vjs-load-progress {
  /* For IE8 we'll lighten the color */
  background: lighten($slider-bg-color, 25%);
  /* Otherwise we'll rely on stacked opacities */
  background: rgba($slider-bg-color, 0.5);
}

/* The load progress bar also has internal divs that represent
 smaller disconnected loaded time ranges */
.video-js .vjs-load-progress div {
  /* For IE8 we'll lighten the color */
  background: lighten($slider-bg-color, 50%);
  /* Otherwise we'll rely on stacked opacities */
  background: rgba($slider-bg-color, 0.75);
}

Answer 1

我们可以用 pseudo 个元素来做到这一点，查看演示

.box {
  width: 200px;
  height: 200px;
  margin: 15px auto;
  background: #999;
  position: relative;
}
.box:before {
  position: absolute;
  content: "";
  width: 30px;
  height: 30px;
  top: -2px;
  left: -2px;
  z-index:-1;
  border-left: 2px solid red;
  border-top: 2px solid red;
}
.box:after {
  position: absolute;
  content: "";
  width: 30px;
  height: 30px;
  right: -2px;
  bottom: -2px;
  z-index:-1;
  border-right: 2px solid red;
  border-bottom: 2px solid red;
}

<div class="box"></div>

Answer 2

我会这样写这个按钮，请根据您的设计重写您的单位：

    .play-icon {position:relative;}
    .play-icon:before {content: '';position:absolute;left:-1px;top:-1px; 
width:10px; height:10px; border-left:1px solid #fff; border-top:1px solid #fff; 
display:inline-block; }
    .play-icon:after {content: '';position:absolute;right:-1px;bottom:-1px; 
width:10px; height:10px; border-right:1px solid #fff; 
border-bottom:1px solid #fff; display:inline-block; }

Answer 3

您可以使用一个元素并使用 pseudo-elements 创建边框，对于箭头，您可以使用 special-char。您也可以使用 Flexbox 进行对齐。

body {
  background: #000000;
}
.button {
  margin: 50px;
  width: 100px;
  height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #1E232C;
  color: white;
  font-size: 20px;
  position: relative;
}
.button:before,
.button:after {
  width: 30px;
  height: 30px;
  content: '';
  position: absolute;
}
.button:before {
  border-top: 1px solid white;
  border-left: 1px solid white;
  top: 0;
  left: 0;
}
.button:after {
  border-right: 1px solid white;
  border-bottom: 1px solid white;
  bottom: 0;
  right: 0;
}

<div class="button">►</div>

Answer 4

使用 :before 和 :after 的组合，您可以获得您想要的效果。

想法是使用 :before 和 :after pseudo-elements 在您的元素中创建 2 个较小的正方形，并在它们的 top/left 和 bottom/right 边。

由于您的设计要求白色边框在按钮外偏移，我们将使用负定位。

html,
body {
  height: 100%;
  width: 100%;
  background-color: #000000;
}

.container {
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}

.btnPlay {
  position: relative;
  color: #ffffff;
  font-size: 20px;
  width: 100px;
  height: 100px;
  line-height: 100px;
  text-align: center;
  background-color: #222222;
  transition: background 0.1s ease-out;
}

.btnPlay:before,
.btnPlay:after {
  content: "";
  position: absolute;
  display: block;
  width: 25px;
  height: 25px;
}

.btnPlay:before {
  top: -1px;
  left: -1px;
  border-left: 1px solid #ffffff;
  border-top: 1px solid #ffffff;
}

.btnPlay:after {
  bottom: -1px;
  right: -1px;
  border-right: 1px solid #ffffff;
  border-bottom: 1px solid #ffffff;
}

.btnPlay:hover {
  cursor: pointer;
  background-color: #292929;
}

<div class="container">
  <div class="btnPlay">
    &#9658;
  </div>
</div>

Answer 5

如果你不喜欢伪元素：

body { background: #555; }

.parent, .main { position: relative; height: 100px; width: 100px; }
.main { background-color: navy; z-index: 2; }
.sub { position: absolute; background-color: white; height: 30px; width: 30px; z-index: 1; }
.sub.tl { top:-1px; left:-1px; }
.sub.br { bottom:-1px; right:-1px; }

<div class="parent">
  <div class="main"></div>
  <div class="sub tl"></div>
  <div class="sub br"></div>
</div>

Answer 6

这可以通过使用 CSS pseudo elements. 来实现您只需要创建两个白框并将它们放在它们的父项下方，仅使用负值 z-index在伪元素上，因为如果您将 z-index 设置为父元素，伪元素将不知道如何处理它们的 z-index 因为父元素的 z-index 具有更大的权重。

这是一个有效的 Fiddle.

<div class="container">
  <div class="play-box"></div>
</div>

body {
  background: black;
}

.play-box {
  margin: 5rem;
  width: 200px;
  height: 200px;
  background: #2f2f2f;
  position: relative;
}

.play-box::before,
.play-box::after {
  position: absolute;
  content: '';
  background: #fff;
  width: 50px;
  height: 50px;
  z-index: -1;
}

.play-box::before {
  left: -1px;
  top: -1px;
}

.play-box::after {
  right: -1px;
  bottom: -1px;
}

Answer 7

为什么不使用 box-shadow 而不是角使用伪元素？

html,body{
  background: black;
  height: 100%;
}
.player{
  background: #333;
  box-shadow: 16px 16px 0 -15px white, -16px -16px 0 -15px white;
  display: block;
  height: 50px;
  margin: 50px auto;
  position: relative;
  width: 50px;
}
.player::before{
  border-color: transparent transparent transparent white;
  border-style: solid;
  border-width: 10px;
  content: "";
  display: block;
  left: 20px;
  position: absolute;
  top: 15px;
}

<span class="player"></span>

Answer 8

既然回答了，这里是一些信息的方法（包括悬停效果和半径的测试）没有伪和 CSS(3) :

（正如我一天前评论的那样使用阴影和渐变）。

SVG 不涉及也不是必需的，但也可以完成这项工作。

div:nth-child(1),div:nth-child(6),div:nth-child(11) {
  box-shadow: 
    -70px -70px 0 -67px red, 
     70px  70px 0 -67px red;
}
div:nth-child(1):hover,div:nth-child(6):hover,div:nth-child(11):hover {
  box-shadow: 
    -70px -70px 0 -67px red, 
     70px  70px 0 -67px red, 
      0     0   0  3px gold;
}

div:nth-child(2),div:nth-child(7),div:nth-child(12) {
  background: 
    linear-gradient(#333, #333) no-repeat center, 
    linear-gradient(to bottom right, red 20%, transparent 20%, transparent 80%, red 80%) no-repeat center ;
  background-size: 
    auto auto, 
    200px 200px;
}
div:nth-child(2):hover, div:nth-child(7):hover,div:nth-child(12):hover {
  background: 
    linear-gradient(#333, #333) no-repeat center, 
    linear-gradient(to bottom right, red 20%, transparent 20%, transparent 80%, red 80%) no-repeat center,
    white;
  background-size: 
    auto auto, 
    200px 200px;
}
div:nth-child(3),div:nth-child(8),div:nth-child(13) {
  border:none;
  padding:3px;
  background:
    linear-gradient(red,red) no-repeat top left,
    linear-gradient(red,red) no-repeat top left,
    linear-gradient(red,red) no-repeat bottom right,
    linear-gradient(red,red) no-repeat bottom right,
    linear-gradient(#333,#333) center no-repeat ;
  background-size: 
    40% 3px, 
    3px 40%,
    40% 3px, 
    3px 40%, 
    auto auto;
  background-clip:
    border-box,
    border-box,
    border-box,
    border-box,
    content-box;
    
}
div:nth-child(3):hover, div:nth-child(8):hover,div:nth-child(13):hover {
  border:none;
  padding:3px;
  background:
    linear-gradient(red,red) no-repeat top left,
    linear-gradient(red,red) no-repeat top left,
    linear-gradient(red,red) no-repeat bottom right,
    linear-gradient(red,red) no-repeat bottom right,
    linear-gradient(#333,#333) center no-repeat, 
    green ;
  background-size: 
    40% 3px, 
    3px 40%,
    40% 3px, 
    3px 40%, 
    auto auto;
  background-clip:
    border-box,
    border-box,
    border-box,
    border-box,
    content-box;
    
}

div {
  width: 200px;
  height:200px;
  margin: 10px;
  background: #333;
  border: solid transparent;
  box-sizing: border-box;
  display:inline-flex;
  vertical-align:middle;
  flex-direction:column;
  align-items:center;
  justify-content:center;
  text-align:center;
  color:white;
}
hr~div {
  border-radius:5px;
}
hr~hr~div {
  border-radius:25px;
}
html {
  background:gray;
  text-align:center
}

<div>red broken borders drawn via <code>shadow</code>
</div>
<div>red broken borders drawn via <code>linear&shy;-gradient</code> 
</div>
<div>red broken borders drawn via multiple <code>linear&shy;-gradient</code> & <code>background&shy;-clip, background&shy;-size, background&shy;-position</code> 
</div>
<hr/>
<p>Can a small <code>border-radius</code> be applied ?</p>
<div>red broken borders drawn via <code>shadow</code>
</div>
<div>red broken borders drawn via <code>linear&shy;-gradient</code> 
</div>
<div>red broken borders drawn via multiple <code>linear&shy;-gradient</code> & <code>background&shy;-clip, background&shy;-size, background&shy;-position</code> 
</div>
<hr/>
<p>Can a big <code>border-radius</code> be applied ?</p>
<div>red broken borders drawn via <code>shadow</code>
</div>
<div>red broken borders drawn via <code>linear&shy;-gradient</code> 
</div>
<div>red broken borders drawn via multiple <code>linear&shy;-gradient</code> & <code>background&shy;-clip, background&shy;-size, background&shy;-position</code> 
</div>

如果您确实需要更大半径的修复，请在第三个示例中重新排序 bg-gradient 和 background-size。请参阅 codepen 中的第 10 个 div 来玩 ;)

带边框的正方形 div。只显示角落

Square div with border. Only show the corners

html

css

css-shapes