body {
    width: fit-content;
}

.menu {
    display: flex;
    flex-direction: column; 
    width: 200px;    
}

.menu h2 {
    all: revert;
    background-color: navy;
    color: white;
    font-size: 1em;
    padding: .1em;
    margin: .25em;
}

.menu h3 {
    all: revert;
    color: navy;
    margin: .5em 0 0 0;
}

.menu a {
    margin-left: .5em;
}

.padding-em-1 {
    padding: 1em;
}

.padding-em-2 {
    padding: 0.5em;
}

.padding-em-3 {
    padding: 0.25em;
}

#contents_of_sub {
    margin: .25em;
    display: flex;
    flex-direction: column;
    background-color: #6FC;
    padding: .5em;
}

#contents_of_sub::before {
    content: "ページ目次";
    color: navy;
    font-weight: bold;
    font-size: 1.2em;
}

#contents_of_sub a {
    margin-left: 0;
}

#contents_of_sub a.H4 {
    margin-left: .5em;
    font-size: 0.8em;
    line-height: 1.1em;
}