.fixed-nav {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: #fff;
    z-index: 1000;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    transition: transform 1s ease-in-out, opacity 1s ease-in-out;
    transform: translateY(-100%);
    opacity: 0;
    display: none; /* デフォルトでは非表示 */
}

.fixed-nav.slide-in {
    transform: translateY(0);
    opacity: 1;
}

.fixed-nav ul {
    display: flex;
    list-style-type: none;
    margin: 0;
    padding: 10px;
    justify-content: space-around;
}

.fixed-nav ul li {
    margin: 0 10px;
}

.fixed-nav ul li a {
    text-decoration: none;
    color: #000;
    font-weight: bold;
    position: relative;
}

.fixed-nav ul li a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    display: block;
    margin-top: 5px;
    left: 0;
    background: #ddd;
    transition: width 0.3s ease;
    -webkit-transition: width 0.3s ease;
}

.fixed-nav ul li.active a::after {
    width: 100%;
}

/* スマートフォン表示用のメディアクエリ */
@media (max-width: 767px) {
    .fixed-nav {
        display: block; /* スマートフォンでは表示 */
    }
}