html - How I can make nice looking matrix of buttons with Bootstrap 3?

Question

I have something like that:

<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">

<div class="container">
  <div class="row">
    <div class="col-sm-6">

      <div class="btn-group">
        <button type="button" class="btn btn-default">Button 1</button>
        <button type="button" class="btn btn-default">Button 2</button>
        <button type="button" class="btn btn-default">Button 3</button>
      </div>

      <div class="btn-group">
        <button type="button" class="btn btn-default">Button 4</button>
        <button type="button" class="btn btn-default">Button 5</button>
        <button type="button" class="btn btn-default">Button 6</button>
      </div>

      <div class="btn-group">
        <button type="button" class="btn btn-default">Button 7</button>
        <button type="button" class="btn btn-default">Button 8</button>
        <button type="button" class="btn btn-default">Button 9</button>
      </div>

    </div>

    <div class="col-sm-6">
    </div>
  </div>
</div>

Answer 1

One group of buttons + few pseudo-classes

1. Use only one block with the .btn-group class.

2. Apply a set of CSS properties by using of pseudo-classes:

• :first-child
• :last-child
• :nth-child()
• :nth-last-child()

3. The clear: left; property forces the button to start a new row of the matrix. It's because the .btn class has the float: left; property.

4. Set up border-radius and margin properties in a similar way as the btn-group class is described in the bootstrap.css file.

Three column button matrix with Bootstrap 3

https://codepen.io/glebkema/pen/bGWWMRz

@import "https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css";

/* Arrange buttons */
.btn-matrix>.btn {
  width: 33%; /* force buttons to have the same width regardless of content */
}
.btn-matrix>.btn:nth-child(3n + 4) {
  clear: left; /* force the button to start a new row of the matrix
                  (because .btn adds the `float: left;` property) */
  margin-left: 0; /* because .btn-group adds `margin-left: -1px;` to all buttons */
}
.btn-matrix>.btn:nth-child(n + 4) {
  margin-top: -1px; /* superimpose borders of the buttons from adjacent rows */
}

/* Fix border radius */
.btn-matrix>.btn:first-child {
  border-bottom-left-radius: 0;
}
.btn-matrix>.btn:nth-child(3) {
  border-top-right-radius: 4px !important;
}
.btn-matrix>.btn:nth-last-child(3) {
  border-bottom-left-radius: 4px !important;
}
.btn-matrix>.btn:last-child {
  border-top-right-radius: 0;
}

/* Decorations */
.btn-matrix {
  margin: 20px;
}

<div class="btn-group btn-matrix">
  <button type="button" class="btn btn-default">Button 1</button>
  <button type="button" class="btn btn-default">Button 2</button>
  <button type="button" class="btn btn-default">Button 3</button>
  <button type="button" class="btn btn-default">Button 4</button>
  <button type="button" class="btn btn-default">Button 5</button>
  <button type="button" class="btn btn-default">Button 6</button>
  <button type="button" class="btn btn-default">Button 7</button>
  <button type="button" class="btn btn-default">Button 8</button>
  <button type="button" class="btn btn-default">Button 9</button>
  <button type="button" class="btn btn-default">Button 10</button>
  <button type="button" class="btn btn-default">Button 11</button>
  <button type="button" class="btn btn-default">Button 12</button>
  <button type="button" class="btn btn-default">Button 13</button>
  <button type="button" class="btn btn-default">Button 14</button>
  <button type="button" class="btn btn-default">Button 15</button>
</div>