Columns

Responsive columns same height (CSS or SASS only)

You have to add a div with the class .row-height inside the row, and also add .col-height to the columns. If you want to restrict the effect to a certain media query, just use the responsive .row-height and .col-height classes: for example .row-sm-height with .col-sm-height.

CSS version:

.row-height {
  display: table;
  table-layout: fixed;
  height: 100%;
  width: calc(100% + 30px);
}
.col-height {
  display: table-cell;
  float: none;
  height: 100%;
}
.col-top {
  vertical-align: top;
}
.col-middle {
  vertical-align: middle;
}
.col-bottom {
  vertical-align: bottom;
}

@media (min-width: 480px) {
  .row-xs-height {
    display: table;
    table-layout: fixed;
    height: 100%;
    width: 100%;
  }
  .col-xs-height {
    display: table-cell;
    float: none;
    height: 100%;
  }
  .col-xs-top {
    vertical-align: top;
  }
  .col-xs-middle {
    vertical-align: middle;
  }
  .col-xs-bottom {
    vertical-align: bottom;
  }
}

@media (min-width: 768px) {
  .row-sm-height {
    display: table;
    table-layout: fixed;
    height: 100%;
    width: 100%;
  }
  .col-sm-height {
    display: table-cell;
    float: none;
    height: 100%;
  }
  .col-sm-top {
    vertical-align: top;
  }
  .col-sm-middle {
    vertical-align: middle;
  }
  .col-sm-bottom {
    vertical-align: bottom;
  }
}

@media (min-width: 992px) {
  .row-md-height {
    display: table;
    table-layout: fixed;
    height: 100%;
    width: calc(100% + 30px);
  }
  .col-md-height {
    display: table-cell;
    float: none;
    height: 100%;
  }
  .col-md-top {
    vertical-align: top;
  }
  .col-md-middle {
    vertical-align: middle;
  }
  .col-md-bottom {
    vertical-align: bottom;
  }
  .row-md-height .col-md-3 {
    width: 25%;
    min-width: 25%; 
    max-width: 25%; 
  }
}

@media (min-width: 1200px) {
  .row-lg-height {
    display: table;
    table-layout: fixed;
    height: 100%;
    width: 100%;
  }
  .col-lg-height {
    display: table-cell;
    float: none;
    height: 100%;
  }
  .col-lg-top {
    vertical-align: top;
  }
  .col-lg-middle {
    vertical-align: middle;
  }
  .col-lg-bottom {
    vertical-align: bottom;
  }
}

SASS version (needed bootstrap _variables.scss):

@import "../bootstrap/variables.scss";
$sizes: xs sm md lg;
$screens: $screen-xs-min $screen-sm-min $screen-md-min $screen-lg-min;

//general
.row-height {
  display: table;
  table-layout: fixed;
  height: 100%;
  width: calc(100% + $grid-gutter-width);
}
.col-height {
  display: table-cell;
  float: none;
  height: 100%;
}
.col-top {
  vertical-align: top;
}
.col-middle {
  vertical-align: middle;
}
.col-bottom {
  vertical-align: bottom;
}

//different sizes
@for $i from 1 through length($sizes) {
    $size: nth($sizes, $i);
    $screen: nth($screens, $i);
    
    @media (min-width: #{$screen}) {
      .row-#{$size}-height {
        display: table;
        table-layout: fixed;
        height: 100%;
        width: 100%;
      }
      .col-#{$size}-height {
        display: table-cell;
        float: none;
        height: 100%;
      }
      .col-#{$size}-top {
        vertical-align: top;
      }
      .col-#{$size}-middle {
        vertical-align: middle;
      }
      .col-#{$size}-bottom {
        vertical-align: bottom;
      }
    } 
 
}