Vivaldi browser look and feel tweak. Screenshot: http://imgur.com/a/kOAov

custom.css

button.vivaldi {
    display: none !important;
}

#tabs-container.top {
    margin-left: -1.8%;
    margin-top: -0.5%;
    background-color: #0063B1;
}

#tabs-container.left,#tabs-container.right {
    background-color:#0063B1
}

.tab:not(.active) {
    color: #E0E0E0;
    background-color:#0063B1!important;
}

.newtab {
    fill: hsla(0, 0%, 100%, .6)!important;
}

.toggle-trash {
    fill: hsla(0, 0%, 100%, .6)!important;
}

#browser .window-buttongroup {
    height: 36px!important;
    vertical-align: middle!important;
}

#browser .window-buttongroup button {
    height: 36px!important;
    vertical-align: middle!important;
    padding-bottom: 5px;
    color: #ffffff!important;
    fill: hsla(0, 100%, 100%, .6)!important;
}