una/install/css/styles.css

html, body {
    margin: 0;
	height: 100%;
}

.bx-install-permissions .bx-btn,
.bx-install-initial .bx-btn {
    display:inline;
    display:inline-block;
    float:none;
}

.bx-install-page {
	min-height: 100%;
	height: auto !important;
	height: 100%;
	margin: 0 auto -60px; /* the bottom margin is the negative value of the footer's height */
}
.bx-install-footer-push,
.bx-install-footer {
    height: 60px;
    line-height: 60px;
}

.bx-install-footer-text {
    float:left;
}

.bx-install-footer-copyright {
    float:right;
}

.bx-install-initial {
    text-align:center;
}

.bx-install-initial img.bx-install-dolphin {
    display:block;
    margin-left:auto;
    margin-right:auto;
    width:500px;
    max-width:90%;
}

.bx-install-initial-langs {
    text-align:center;
}

.bx-install-initial-langs img {
    width:32px;
    height:32px;
}

.bx-install-permissions-buttons {
    text-align:center;
}