Margins on equal height columns not working

Question

I have 3 columns that extend to equal height. The only problem is that I need a gap between each column.

Fiddle Demo

I have tried to place a float:left in #wrapper > .col (see bellow) and it worked but then it messes up the columns heights.

Is there any way to fix this issue?

#wrapper > .col {
    display: table-cell;
    width: 30.3%;
    margin: 0 15px 3px;
    background-color: #fff;
    text-align: center;
    position: relative;
    height: 100%;
    padding-bottom: 2px;
    border:1px solid #000;
    float:left;
}

CSS

.content > img {
    vertical-align:top;
}
#wrapper {
    height: 100%;
    width: 100%;
    margin: 20px auto;
    display:table;
    overflow: hidden;
}
#wrapper > .col {
    display: table-cell;
    width: 30.3%;
    margin: 0 15px 3px;
    background-color: #fff;
    text-align: center;
    position: relative;
    height: 100%;
    padding-bottom: 2px;
    border:1px solid #000;
}
#wrapper > .col > .content {
    padding:0 0 35px;
    height:100%;
}
.content {
    margin-bottom:30px;
    position: relative;
}
.content > p {
    vertical-align:top;
}
.content h3 {
    font-size:1.375rem;
    font-weight:400;
    text-align:center;
    margin-bottom: 20px;
    padding: 25px 27px 0;
}
.content p {
    text-align:left;
    padding: 0 27px 30px;
}
.button.moreinfo {
    margin-top: 5px;
    margin-bottom: 0;
    padding-top: 0.5rem;
    padding-right: 0.3rem;
    padding-bottom: 0.5rem;
    padding-left: 0.3rem;
    background-color: #2a2a2a;
    font-size: 0.9rem;
    color: #f39c12;
    font-weight: 400 !important;
}
div.btn-align-bottom {
    position:absolute;
    bottom:50px;
    left:0;
    right:0;
}
.info-box {
    margin-bottom:0;
    margin-top: 15px;
}
.info-box img {
    max-width: 100%;
    max-height: 100%;
    vertical-align: middle;
}
.info-box-inner {
    background: #FFF;
    padding:25px 27px 35px;
    display:inline-block;
    overflow:hidden;
    float:none;
    min-height:270px;
    text-align:center;
    -moz-box-shadow: 0px 1px 2px rgba(48, 48, 48, 0.3);
    -webkit-box-shadow: 0px 1px 2px rgba(48, 48, 48, 0.3);
    box-shadow: 0px 1px 2px rgba(48, 48, 48, 0.3);
    z-index:1;
}
.info-box-inner p {
    text-align:left;
}
.info-box-inner h3 {
    font-size:1.375rem;
    font-weight:400;
    text-align:center;
}

Answer 1

The border-spacing property is the one you should use (margins don't apply to internal table objects). But it only applies to tables, not to cells. You should set the border-spacing on the ancestor element that has a display value of table.

In addition to your code you can try like this

#wrapper{
 border-spacing:10px;
 display:table;
}

#wrapper > .col {
    display: table-cell;
    /* margin: 0 15px 3px;*/
    padding:10px;

}