Noty theme in CSS (not in JS as it recommends by default)

noty_flat_theme.css

/**
 * Noty 2.2.2 Theme: Flat UI colors
 * @author kottenator
 */
.flat .noty_bar {
    font: 16px/1.3 Arial, Liberation Sans, sans-serif;
    text-align: center;
    padding: 12px 15px 13px;
    position: relative;
    border: 2px solid #eee;
    background-color: #fff;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}

.flat:first-child .noty_bar {
    border-top-width: 2px;
    border-top-left-radius: 5px;
    border-top-right-radius: 5px;
}

#noty_top_layout_container .flat:first-child .noty_bar {
    border-top: none;
    border-top-left-radius: 0;
    border-top-right-radius: 0;
}

.flat:last-child .noty_bar {
    border-bottom-width: 2px;
    border-bottom-left-radius: 5px;
    border-bottom-right-radius: 5px;
}

#noty_bottom_layout_container .flat:last-child .noty_bar {
    border-bottom: none;
    border-bottom-left-radius: 0;
    border-bottom-right-radius: 0;
}

.flat .noty_bar.noty_type_error {
    background-color: #e74c3c;
    border-color: #c0392b;
    color: #fff;
}

.flat .noty_bar.noty_type_warning {
    background-color: #f1c513;
    border-color: #f39c12;
    color: #fff;
}

.flat .noty_bar.noty_type_success {
    background-color: #2ecc71;
    border-color: #27ae60;
    color: #fff;
}

.flat .noty_bar.noty_type_information {
    background-color: #3498db;
    border-color: #2980b9;
    color: #fff;
}

.flat.noty_container_type_alert + .flat.noty_container_type_alert,
.flat.noty_container_type_error + .flat.noty_container_type_error,
.flat.noty_container_type_warning + .flat.noty_container_type_warning,
.flat.noty_container_type_success + .flat.noty_container_type_success,
.flat.noty_container_type_information + .flat.noty_container_type_information,
.flat.noty_container_type_confirm + .flat.noty_container_type_confirm {
    margin-top: -2px;
}

noty_flat_theme.js

noty({ text: "Great success!", theme: "flat", type: "success" });

noty_flat_theme.scss

/**
* Noty 2.2.2 Theme: Flat UI colors
* @author kottenator
*/
.flat {
    .noty_bar {
        font: 16px/1.3 Arial, Liberation Sans, sans-serif;
        text-align: center;
        padding: 12px 15px 13px;
        position: relative;
        border: 2px solid #eee;
        background-color: #fff;
        -webkit-box-sizing: border-box;
        -moz-box-sizing: border-box;
        box-sizing: border-box;
    }

    &:first-child .noty_bar {
        border-top-width: 2px;
        border-top-left-radius: 5px;
        border-top-right-radius: 5px;

        #noty_top_layout_container & {
            border-top: none;
            border-top-left-radius: 0;
            border-top-right-radius: 0;
        }
    }

    &:last-child .noty_bar {
        border-bottom-width: 2px;
        border-bottom-left-radius: 5px;
        border-bottom-right-radius: 5px;

        #noty_bottom_layout_container & {
            border-bottom: none;
            border-bottom-left-radius: 0;
            border-bottom-right-radius: 0;
        }
    }

    .noty_bar.noty_type_error {
        background-color: #e74c3c;
        border-color: #c0392b;
        color: #fff;
    }

    .noty_bar.noty_type_warning {
        background-color: #f1c513;
        border-color: #f39c12;
        color: #fff;
    }

    .noty_bar.noty_type_success {
        background-color: #2ecc71;
        border-color: #27ae60;
        color: #fff;
    }

    .noty_bar.noty_type_information {
        background-color: #3498db;
        border-color: #2980b9;
        color: #fff;
    }
}

@each $type in alert, error, warning, success, information, confirm {
    .flat.noty_container_type_#{$type} + .flat.noty_container_type_#{$type} {
        margin-top: -2px;
    }
}