.container {
    position: absolute;
    bottom: 16px;
    left: 16px;
    
    background-color: rgba(0, 0, 0, .6);
    color: #fff;
    font-weight: 100;
    padding: 8px;
    
    box-shadow: 0 0 16px rgba(0, 0, 0, .5);
}

.container > .button1 {
    opacity: 0.5;
    float: left;
    display: inline-block;
    font-size: 18px;
    padding: 0 12px;
    line-height: 24px;
    border-radius: 4px;
    cursor: pointer;
    
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

.container > .button2 {
    opacity: 0.5;
    float: left;
    display: inline-block;
    font-size: 18px;
    padding: 0 12px;
    line-height: 24px;
    border-radius: 4px;
    cursor: pointer;
    
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}
.container > .button3 {
    opacity: 0.5;
    float: left;
    display: inline-block;
    
    padding: 0 12px;
    font-size: 18px;
    line-height: 24px;
    border-radius: 4px;
    cursor: pointer;
    
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

.container > .button4 {
    opacity: 0.5;
    float: left;
    display: inline-block;
    
    padding: 0 12px;
    font-size: 18px;
    line-height: 24px;
    border-radius: 4px;
    cursor: pointer;
    
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

.container > .button1:hover {opacity: 1;}
.container > .button2:hover {opacity: 1;}
.container > .button3:hover {opacity: 1;}
.container > .button4:hover {opacity: 1;}