CSS - border-block-width Property

The width of logical block borders is defined by the CSS property border-block-width, which maps to a physical border width depending on the writing mode, directionality, and text orientation of the element.

Depending on the values provided for writing-mode, direction, and text-orientation, its mapping relates to either the border-left-width and border-right-width, or the border-top-width and border-bottom-width properties.
The border-inline-width property may be used to define the border width in the other dimensions. Both the border-inline-start-width and border-inline-end-width values are configured.

Possible value

<'border-width'> - The width of the border.

Syntax

border-block-width = <'border-top-width'>{1,2}

Applies to

All the HTML elements.

CSS border-block-width - thin value

The following example demonstrates the usage of border-block-width property along with thin width value.

<html>
<head>
<style>
   body {
      font-family: 'Arial', sans-serif;
      margin: 50px;
      padding: 50px;
      background-color: #f0f0f0;
   }
   .new-container {
      background-color: #f0e8e6;
      width: 400px;
      height: 400px;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 15px;
      box-shadow: 4px 4px 12px rgba(0, 0, 0, 0.8);
   }
   .custom-border {
      border: 4px dashed #e74c3c;
      border-block-width: thin;
      padding: 15px;
      margin: 10px;
      font-size: 22px;
      font-weight: bold;
      color: #333;
   }
</style>
</head>
<body>
<div class="new-container">
<p class="custom-border">A example with border-block-width property with thin style</p>
</div>
</body>
</html>

CSS border-block-width - medium value

The following example demonstrates the usage of border-block-width property along with medium width value.

<html>
<head>
<style>
   body {
      font-family: 'Arial', sans-serif;
      margin: 50px;
      padding: 50px;
      background-color: #f0f0f0;
   }
   .new-container {
      background-color: #ebad9b;
      width: 400px;
      height: 400px;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 15px;
      box-shadow: 4px 4px 12px rgba(0, 0, 0, 0.8);
   }
   .custom-border {
      border: 4px dashed #b5401d;
      border-block-width: medium;
      padding: 15px;
      margin: 10px;
      font-size: 22px;
      font-weight: bold;
      color: #333;
   }
</style>
</head>
<body>
<div class="new-container">
<p class="custom-border">A example with border-block-width property with medium style</p>
</div>
</body>
</html>

CSS border-block-width - thick Value

The following example demonstrates the usage of border-block-width property along with thick width value.

<html>
<head>
<style>
   body {
      font-family: 'Arial', sans-serif;
      margin: 50px;
      padding: 50px;
      background-color: #f0f0f0;
   }
   .new-container {
      background-color: #ced7f0;
      width: 400px;
      height: 400px;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 15px;
      box-shadow: 4px 4px 12px rgba(0, 0, 0, 0.8);
   }
   .custom-border {
      border: 2px dashed #134ef0;
      border-block-width: thick;
      padding: 15px;
      margin: 10px;
      font-size: 22px;
      font-weight: bold;
      color: #333;
   }
</style>
</head>
<body>
<div class="new-container">
<p class="custom-border">A example with border-block-width property with thick  style</p>
</div>
</body>
</html>

CSS border-block-width - length Value

The following example demonstrates the usage of border-block-width property along with length value.

<html>
<head>
<style>
   body {
      font-family: 'Arial', sans-serif;
      margin: 50px;
      padding: 50px;
      background-color: #f0f0f0;
   }
   .new-container {
      background-color: #f5f3e1;
      width: 400px;
      height: 400px;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 15px;
      box-shadow: 4px 4px 12px rgba(0, 0, 0, 0.8);
   }
   .custom-border {
      border: 2px solid #9c9105;
      border-block-width: 5px 10px;
      padding: 15px;
      margin: 10px;
      font-size: 20x;
      font-weight: bold;
      color: #333;
   }
</style>
</head>
<body>
<div class="new-container">
<p class="custom-border">A example with border-block-width property.</p>
</div>
</body>
</html>

CSS border-block-width - Writing mode

The following example demonstrates the usage of border-block-style property with vertical writing mode.

<html>
<head>
<style>
   .custom-div {
      background-color: gray;
      width: 450px;
      height: 350px;
   }
   .demo-border {
      writing-mode: vertical-rl;
      border: 1px solid blue;
      border-block-width: 5px; 
      padding: 15px;
      margin: 10px;
      color: #fff;
      font-size: 22px;
   }
</style>
</head>
<body>
<div class="custom-div">
<p class="demo-border">This is a example with border-block-width property.</p>
</div>
</body>
</html>