CSS Bootstrap Multi-Select Dropdown Box Width Set to 100%

In this article, we’ll show you how to use CSS and Bootstrap to set the width of a multi-select dropdown box to 100%. This will make the multi-select dropdown box adapt to the width of its container, making it more beautiful and easier to use.

Read more: CSS Tutorial

Using Bootstrap’s Multi-Select Dropdown Component

To create a 100% width multi-select dropdown, we can use the Dropdown component provided by Bootstrap. This component not only implements multiple selections but also has a responsive design that adapts to different screen sizes.

First, we need to include Bootstrap’s CSS and JavaScript files in our HTML document. Then, insert the following code where the drop-down box should be:

<div class="dropdown">
<button class="btn btn-default dropdown-toggle" type="button" data-toggle="dropdown">
Please select <span class="caret"></span>
</button>
<ul class="dropdown-menu" style="width: 100%;">
<li><input type="checkbox"> Option 1</li>
<li><input type="checkbox"> Option 2</li>
<li><input type="checkbox"> Option 3</li>
<!-- Add more options -->
</ul> 
</div> 

In this example, we use the Bootstrap dropdown component and set the dropdown width to 100% by setting style="width: 100%" on the <ul> element. As you can see, the dropdown automatically adapts to the width of its container, ensuring it displays properly on all screen sizes.

Customizing the Width of a Multiple-Select Dropdown

In addition to using the Bootstrap dropdown component, you can also customize the width of a multiple-select dropdown. This approach is more flexible and can be adjusted to your needs.

First, we need to set the dropdown container to a block-level element with a fixed width. For example, add the following code to your CSS stylesheet:

.dropdown-container {
width: 400px;
}

Then, use the following code in your HTML document to create a custom-width multiple-select dropdown:

<div class="dropdown-container">
<select multiple class="form-control">
<option>Option 1</option>
<option>Option 2</option>
<option>Option 3</option>
<!-- Add more options -->
</select>
</div>

In this example, we use the form-control class provided by Bootstrap to style the dropdown and set the width of the dropdown container to 400px. You can adjust the width value according to actual situation.

Using CSS to Implement Adaptive Width for a Multi-Select Dropdown

If you don’t want to use Bootstrap’s dropdown component, or want more granular control over the style of your multi-select dropdown, you can also achieve adaptive width using pure CSS.

First, we need to set the dropdown container to a relatively positioned element and the dropdown inside it to an absolutely positioned element. Then, use left: 0; right: 0; to align the left and right edges of the dropdown with the parent container, and set width: 100%; to adapt the dropdown’s width to the parent container.

Here is a sample CSS code:

.dropdown-container {
position: relative;
width: 400px;
} 

.dropdown-menu {
position: absolute;
left: 0;
right: 0;
width: 100%;
} 

Then, use the following code in the HTML document to create a custom-styled multiple-select drop-down box:

<div class="dropdown-container"> 
<div class="dropdown-menu"> 
<select multiple class="form-control"> 
<option>Option 1</option> 
<option>Option 2</option> 
<option>Option 3</option> 
<!-- Add more options --> 
</select>
</div>

</div>

This method allows you to control the width of a select dropdown to your needs and flexibly adjust its style.

Summary

This article introduced three methods for setting the width of a Bootstrap select dropdown to 100% using CSS. You can choose to use Bootstrap’s dropdown component, customize the width of the select dropdown, or achieve adaptive width using pure CSS. Either way, you can make your select dropdown more aesthetically pleasing and easier to use. I hope this article is helpful!