Modal without Js

HTML

<div class="ibs-full-modal-container" id="modal1">
    <div class="ibs-full-modal">
        <header class="ibs-modal-header">
            <h4 class="ibs-modal-title">Default Modal</h4>
            <span class="ibs-btn-close">&times;</span>
        </header>
        <div class="ibs-modal-body has-header has-footer"></div>
        <div class="ibs-modal-footer text-right">
            <button class="btn btn-default" id="closeBtn">Cancel</button>
            <button class="btn btn-success">Confirm</button>
        </div>
    </div>
</div>

<button id="openBtn" class="btn btn-primary btn-lg">open modal</button>

CSS

.ibs-backdrop,
.ibs-full-modal-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: #000;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1;
    display: none;
}
.ibs-full-modal-container {
    background-color: transparent;
}
.ibs-full-modal {
    position: absolute;
    top: 0;
    left: 240px;
    right: 0;
    bottom: 0;
    -webkit-transform: translateX(30%);
    -moz-transform: translateX(30%);
    -ms-transform: translateX(30%);
    -o-transform: translateX(30%);
    transform: translateX(30%);
    opacity: 0;
}
.ibs-full-modal * {
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}
.ibs-full-modal > .ibs-modal-body,
.ibs-full-modal > .ibs-modal-footer,
.ibs-full-modal > .ibs-modal-header {
    padding: 15px 20px;
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 56px;
    background-color: #eee;
    border-bottom: 1px solid #ccc;
}
.ibs-full-modal > .ibs-modal-body {
    height: auto;
    padding: 20px;
    right: 0;
    bottom: 0;
    background-color: #fff;
    overflow-x: hidden;
    overflow-y: auto;
    border: none;
}
.ibs-full-modal > .ibs-modal-body.has-header {
    top: 56px;
}
.ibs-full-modal > .ibs-modal-body.has-footer {
    bottom: 56px;
}
.ibs-full-modal > .ibs-modal-footer {
    top: auto;
    bottom: 0;
    height: 56px;
    text-align: right;
    border-top: 1px solid #ccc;
    padding: 10px 20px;
}
.ibs-full-modal .ibs-modal-title {
    padding: 5px 0;
    font-size: 18px;
    font-weight: 700;
    float: left;
}
.ibs-full-modal .ibs-btn-close {
    font-size: 30px;
    float: right;
    line-height: 30px;
    text-align: center;
    height: 30px;
    width: 30px;
    -webkit-border-radius: 50%;
    border-radius: 50%;
    -webkit-transition: all 0.3s;
    -o-transition: all 0.3s;
    -moz-transition: all 0.3s;
    transition: all 0.3s;
}
.ibs-full-modal...