.period-calculator-icon {
    display:inline-block;
    width:28px;
    height:28px;
    background: url('/images/svg/period-calculator.svg') no-repeat center center;
    background-size: contain;
}

.ovulation-calculator-icon {
    display:inline-block;
    width:28px;
    height:28px;
    background: url('/images/svg/ovulation-calculator.svg') no-repeat center center;
    background-size: contain;
}