Multiple Input support in Bootstrap 3.3.7 - css

Question

There is a multiple input feature provided in Bootstrap 4 that looks like the following:
<div class="input-group">
<div class="input-group-prepend">
<span class="input-group-text" id="">First and last name</span>
</div>
<input type="text" class="form-control">
<input type="text" class="form-control">
</div>
Is there a trivial way to replicate this behavior using Bootstrap 3.3.7? Would it require stripping styles from Bootstrap 4 or is there something I'm overlooking in 3.3.7 that already allows this behavior? The documentation is available here: https://getbootstrap.com/docs/4.0/components/input-group/#multiple-inputs

Answer 1

I cannot speak to it being trivial or not, but with some additional CSS and with the assistance of the Bootstrap Grid you can achieve similar results:
.input-group-multi [class*='col-'] {
margin: 0 !important;
padding: 0 !important;
}
.input-group-multi .form-control {
border-right: 0;
}
.input-group-multi [class*='col-']:last-child .form-control {
border-radius: 0 4px 4px 0;
border-right: 1px solid #ccc;
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<div class="input-group input-group-multi">
<div class="input-group-addon">First and last name</div>
<div class="col-xs-6"><input type="text" class="form-control"></div>
<div class="col-xs-6 no-gutters"><input type="text" class="form-control"></div>
</div>
<br />
<div class="input-group input-group-multi">
<div class="input-group-addon">First and last name</div>
<div class="col-xs-4"><input type="text" class="form-control"></div>
<div class="col-xs-4"><input type="text" class="form-control"></div>
<div class="col-xs-4"><input type="text" class="form-control"></div>
</div>
<br />
<div class="input-group input-group-multi">
<div class="input-group-addon">First and last name</div>
<div class="col-xs-3"><input type="text" class="form-control"></div>
<div class="col-xs-3"><input type="text" class="form-control"></div>
<div class="col-xs-3"><input type="text" class="form-control"></div>
<div class="col-xs-3"><input type="text" class="form-control"></div>
</div>
In the above code snippet you can see how .input-group-mutli is sort of the heavy-lifter here. With this new class we can use a wildcard match on the Bootstrap Grid column to remove all margin and padding. That alone gets you to where your multiple inputs will line up nicely... but with the borders doubling up.
A little extra CSS to detect remove the right-border and then re-apply that border on the last column+input provides you with a pretty spot on multiple input feature. With one exception of course; this presumes that input-group-addon is always on the left.

Answer 2

A little CSS will give you the same effect.
In the following snippet I created the css class input-multiple and modified the CSS styling accordingly. Adjust field widths as needed, here I simply altered the width:100% associated with Bootstraps .form-control class
.input-multiple>input.form-control {
width: auto;
}
.input-multiple>input.form-control+input.form-control {
border-left: 0;
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<div style="padding:20px">
<div class="row">
<div class="col-lg-6">
<div class="input-group input-multiple">
<span class="input-group-addon" id="sizing-addon1">First and Last Name</span>
<input type="text" class="form-control" placeholder="First Name">
<input type="text" class="form-control" placeholder="Last Name">
</div>
</div>
</div>
</div>