#app {
    display:flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100vh;
}
.form {
    margin: auto;
    max-width: 600px;
    width: 100%;
    padding: 50px;
    background-color: #fff;
    box-shadow: 0 25px 50px rgba(0, 0, 0, .05);
}
.flex {
    display: flex;
}
.flex-c {
    display: flex;
    align-items: center;
}
.flex-c-j {
    display: flex;
    align-items: center;
    justify-content: center;
}

@media screen and (max-width:600px) {
    .form{
        max-width: calc(100% - 30px);
        padding: 15px;
    }
}