Right/left sided triangle in css

Question

Hi i am trying to make the following:

They triangles should be about 40% in height of the container, and 50% in width, so they meet in the middle.

I have been trying to make something similar.. but unsuccessfull so far..

And looking around, i have found nothing i could use so far.

my code:

div {
  height: 373px;
  width: 0px;
  margin: 26px;
  display: inline-block;
}

.left {
  border-bottom: 100px solid #ff0;
  border-left: 320px solid transparent;
}

.right {
  border-bottom: 100px solid #f00;
  border-right: 320px solid transparent;
}

header {
  border: 2px solid black;
  width: 50%;
  height: 500px;
}

<header>
  <div class="right"></div>
  <div class="left"></div>

</header>

hoping for someone smarter than me to see where i should go from here...

Will the dimensions always be hard-coded or should the solution adapt to containers of any size? — Tyler Roper, May 07 '19 at 14:54
Check out http://apps.eky.hk/css-triangle-generator/ and select "Type: scalene" — elveti, May 07 '19 at 14:54
@elveti i do not see how i can make a right sided triangle with this. It will only make even sides ? — andrelange91, May 07 '19 at 14:55
@andrelange91 choose type "Scalene" and you'll be able to change the sizes individually (if I understood your needs correctly) — elveti, May 07 '19 at 14:56
@elveti would almost fix it, but hard coded values would make it unusable for responsive designs. — andrelange91, May 07 '19 at 14:58

Temani Afif · Accepted Answer · 2019-05-07T15:30:09.207

Use background coloration like below:

.box {
  height:300px;
  background:
    /* Right bottom triangle*/
    linear-gradient(to bottom right,transparent 49.5%,blue 50%) bottom right,
    /* left bottom triangle*/
    linear-gradient(to bottom left ,transparent 49.5%,red  50%) bottom left ,
    yellow;
  background-size:50% 40%; /* Width height*/
  background-repeat:no-repeat;
}

<div class="box">

</div>

Related answer for more details: How do CSS triangles work?

Another idea with pseudo elements (that you can replace with common elements) in case you want to have different elements.

.box {
  height: 300px;
  background: yellow;
  position: relative
}

.box:before,
.box:after {
  content: "";
  position: absolute;
  height: 40%;
  width: 50%;
  bottom: 0;
}

.box:before {
  left: 0;
  background: linear-gradient(to bottom left, transparent 49.5%, red 50%);
}

.box:after {
  right: 0;
  background: linear-gradient(to bottom right, transparent 49.5%, blue 50%);
}

<div class="box">

</div>

this does not fix my problem. They are not 40% in height, and they do not meet in the middle. — andrelange91, May 07 '19 at 14:56

score 1 · Answer 2 · answered May 07 '19 at 15:06

Since you need percent values, you can use clip-path. Beware that it may not be supported fully on some browser https://caniuse.com/#feat=css-clip-path and for some you may need prefixes (e.g. -webkit-clip-path)

.wrap {
  height: 200px;
  width: 100%;
  position: relative;
  background: #333;
}
.triangle {
  background: red;
  clip-path: polygon(0 40%, 0% 100%, 100% 100%);
  position: absolute;
  left: 0;
  bottom: 0;
  top: 0;
  width: 50%;
}
.triangle.tr-right {
  left: auto;
  right: 0;
  clip-path: polygon(100% 40%, 0% 100%, 100% 100%);
}

<div class="wrap">
  <div class="triangle tr-left"></div>
  <div class="triangle tr-right"></div>
</div>

JSFiddle

Clip-path created with Clippy

you can simplify by applying height and keeping the clip-path easy: https://jsfiddle.net/enbmqsy6/ — Temani Afif, May 07 '19 at 15:08

score -1 · Answer 3 · answered Jun 08 '21 at 04:44

 * {
        box-sizing: border-box;
      }
      .triangular-pointer-box {
        display: flex;
        align-items: center;
        background: #161616;
        padding: 20px;
        padding-left: 120px;
        height: 200px;
        position: relative;
        width: 80%;
      }
      .triangular-pointer-box > h3 {
        color: #fff;
      }

      .triangular-pointer-box:after {
        content: "";
        width: 0;
        height: 0;
        border-top: 100px solid transparent;
        border-bottom: 100px solid transparent;
        border-left: 100px solid #161616;
        position: absolute;
        right: -100px;
        top: 0;
      }
      .triangular-pointer-box:before {
        content: "";
        width: 0;
        height: 0;
        border-top: 100px solid transparent;
        border-bottom: 100px solid transparent;
        border-left: 100px solid #ffffff;
        position: absolute;
        left: 0;
        top: 0;
      }

<div class="triangular-pointer-box">
      <h3>Title goes here</h3>
    </div>

Right/left sided triangle in css

3 Answers3