#multi-step-form input.invalid {
    border: 2px solid rgba(255, 122, 122, .9) !important;
    background: rgba(255, 122, 122, .5) !important;
    color: rgba(255, 122, 122, .9) !important;
}

/* Hide all steps by default: */
#multi-step-form .tab {
    display: none;
}

/* Make circles that indicate the steps of the form: */
#multi-step-form #step-box {
    box-sizing: border-box;
    text-align: center;
}

#multi-step-form .step {
    height: 30px;
    width: 30px;
    margin: 0 2px;
    background-color: #bbbbbb;
    border: none;
    border-radius: 50%;
    display: inline-block;
    opacity: 0.5;
}

/* Mark the active step: */
#multi-step-form .step.active {
    opacity: 1;
}

/* Mark the steps that are finished and valid: */
#multi-step-form .step.finish {
    background-color: #4CAF50;
}