html {
    display: flex;
    min-height: 100%;
    align-items: flex-start;
    justify-content: center;
    height: 100%;
}

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

body {
    display: flex;
    flex-direction: column;
    height: 100%;
    width: 100%;
}

#main-body {
    display: flex;
    width: 100%;
    border: none;
    flex: 1 1 auto;
}

.place-holder {
    width: 100%;
    height: 100%;
}

.place-holder:empty::before {
    content: attr(data-placeholder);
    color: var(--color-placeholder);
}

@media (min-width: 768px) {
    body {
        flex-direction: row;
    }

}