trilium/static/style.css

.note-editable {
    /* This is because with empty content height of editor is 0 and it's impossible to click into it */
    min-height: 400px;
}

#top-message {
    display: none; /* initial state is hidden */
    background-color: greenyellow;
    color: green;
    padding: 5px;
    border-radius: 10px;
}