mdb-ui-kit/scss/includes/_alerts.scss

.alert {
    border: 0;
    border-radius: 0;

    // SASS conversion note: please mirror any content change in _mixins-shared.scss alert-variations-content
    @include alert-variations(unquote(".alert"), unquote(""), $mdb-text-color-light);

    &-info, &-danger, &-warning, &-success {
        color: $mdb-text-color-light;
    }

    &-default {
        a, .alert-link {
            color: $mdb-text-color-primary;
        }
    }
}