#container {
    display: flex; /* displays flex-items (children) inline */
    flex-direction: column; /* stacks them vertically */
    height: 100%; /* needs to take the parents height, alternative: body {display: flex} */
}

main {
    flex: 1;
    overflow: auto;
}

article {
    height: 100%; /* takes the visible area of the "main" div */
    overflow: auto; /* recommended */
    border-bottom: 1px solid;
    border-top: 1px solid;
    background: lightgreen;
    padding: 5px;
}

ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
}

.aside {
    margin-top: 25px;
    background-color: #016f1d;
    padding: 5px;
    color: #ffffff;
    font-size: 16px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
}

.aside h3 {
    margin-top: 5px;
    text-align: center;
}

/* For mobile phones: */
[class*="col-"] {
    width: 100%;
}

article .btn {
    font-size: 18px;
    font-weight: bold;
    line-height: 50px;
    width: 100%;
    padding: 4px;
    margin-bottom: 3px;
    background-color: #333;
    color: #fff;
    border: none;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
}

article .btn:hover {
    background-color: grey;
}

.text-input {
    width: 100%;
    padding: 5px;
    margin: 5px 0;
}

.zutat {
    width: 100%;
    text-align: center;
    border: none;
}