footer {
    min-height: auto;
}

#openMenuButton {
    display: none;
}

.btn-outline-darkgray {
    color: black;
    border-color: darkgray;
    border-width: 2px;
    background-color: transparent;
    transition: all 0.3s ease;
}

.btn-outline-darkgray:hover {
    color: white;
    background-color: blueviolet;
    border-color: blueviolet;
}

.btn-outline-darkgray:active,
.btn-outline-darkgray:focus {
    color: white;
    background-color: #7a28cc;  /* 少し暗い blueviolet */
    border-color: #7a28cc;
    box-shadow: 0 0 0 0.25rem rgba(138, 43, 226, 0.25);  /* blueviolet の透明バージョン */
}