html {
  font-size: 14px;
}

@media (min-width: 768px) {
  html {
    font-size: 16px;
  }
}

.btn:focus, .btn:active:focus, .btn-link.nav-link:focus, .form-control:focus, .form-check-input:focus {
  box-shadow: 0 0 0 0.1rem white, 0 0 0 0.25rem #258cfb;
}

html {
  position: relative;
  min-height: 100%;
}

body {
  margin-bottom: 60px;
}

<style >
.field-validation-error {
    color: #dc3545;
    font-size: 0.875em;
    display: block;
    margin-top: 0.25rem;
}

.input-validation-error {
    border-color: #dc3545;
}

.validation-summary-errors {
    color: #dc3545;
    margin-bottom: 1rem;
}

.validation-summary-errors ul {
    margin-bottom: 0;
    padding-left: 1.5rem;
}

</style >