app.css

/* 
 * Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license.
 * See LICENSE in the project root for license information.
 */

html,
body {
    width: 100%;
    height: 100%;
    margin: 0;
    padding: 0;
}

ul,
p,
h1,
h2,
h3,
h4,
h5,
h6 {
    margin: 0;
    padding: 0;
}

.ms-welcome {
    position: relative;
    display: -webkit-flex;
    display: flex;
    -webkit-flex-direction: column;
    flex-direction: column;
    -webkit-flex-wrap: nowrap;
    flex-wrap: nowrap;
    min-height: 500px;
    min-width: 320px;
    overflow: auto;
    overflow-x: hidden;
}

.ms-welcome__header {
    min-height: 250px;
    padding: 20px;
    padding-bottom: 30px;
    display: -webkit-flex;
    display: flex;
    -webkit-flex-direction: column;
    flex-direction: column;
    -webkit-flex-wrap: nowrap;
    flex-wrap: nowrap;
    -webkit-align-items: center;
    align-items: center;
    -webkit-justify-content: flex-end;
    justify-content: flex-end;
}

.ms-welcome__header > h1 {
    margin-top: 30px;
    text-align: center;
}

.ms-welcome__main {
    display: -webkit-flex;
    display: flex;
    -webkit-flex-direction: column;
    flex-direction: column;
    -webkit-flex-wrap: nowrap;
    flex-wrap: nowrap;
    -webkit-align-items: center;
    align-items: center;
    -webkit-flex: 1 0 0;
    flex: 1 0 0;
    padding: 30px 20px;
}

.ms-welcome__main > h2 {
    width: 100%;
    text-align: center;
}

.ms-welcome__features {
    list-style-type: none;
    margin-top: 30px;
}

.ms-welcome__features.ms-List .ms-ListItem {
    padding: 0px;
    padding-bottom: 20px;
    display: -webkit-flex;
    display: flex;
    -webkit-flex-direction: row;
    flex-direction: row;
    -webkit-flex-wrap: nowrap;
    flex-wrap: nowrap;
    -webkit-align-items: center;
    align-items: center;
}

.ms-welcome__features.ms-List .ms-ListItem > .ms-Icon {
    font-size: 14pt;
}

.ms-welcome__features.ms-List .ms-ListItem > .ms-Icon {
    margin-right: 10px;
}

.ms-welcome__action.ms-Button--hero {
    margin-top: 30px;
    display: -webkit-flex;
    display: flex;
    -webkit-flex-direction: row;
    flex-direction: row;
    -webkit-flex-wrap: nowrap;
    flex-wrap: nowrap;
    -webkit-justify-content: center;
    justify-content: center;
    -webkit-align-items: center;
    align-items: center;
}

.ms-welcome__action.ms-Button--hero .ms-Button-icon .ms-Icon {
    margin-left: 5px;
    margin-top: 4px;
    border: none;
    font-size: 14pt;
}

.ms-welcome__action.ms-Button--hero:hover .ms-Button-icon .ms-Icon {
    border: none;
}

@media (min-width: 0) and (max-width: 350px) {
    .ms-welcome__features {
        width: 100%;
    }
}