/* ===============================
   nav.css — Header / Navigation
   =============================== */

/* ---------- Base ---------- */
header {
    max-width: 1100px;
    margin: 0 auto;
    padding: 3rem 1.25rem 2.5rem;
    position: relative;
}

/* ---------- Title ---------- */
header .title {
    text-align: center;
    margin-bottom: 1.5rem;
}

header .title a {
    font-size: 1.6rem;
    font-weight: 500;
    letter-spacing: .02em;
    transition: opacity .2s ease;
}

header .title a:hover {
    opacity: 0.8;
}

/* ---------- PC Nav ---------- */
nav.pc-nav {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1.5rem;
    font-size: .9rem;
}

nav.pc-nav a {
    position: relative;
    padding: .25rem 0;
    transition: text-decoration .2s ease;
}

nav.pc-nav a:hover {
    text-decoration: underline;
    text-underline-offset: 4px;
}

/* Dropdown */
.dropdown {
    position: relative;
    display: inline-block;
}

.dropdown-menu {
    position: absolute;
    left: 0;
    top: 1.8rem;
    background: #fff;
    border: 1px solid #e5e7eb;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, .08);
    padding: .5rem 1rem;
    min-width: 120px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-5px);
    transition: all .3s ease;
    z-index: 20;
}

.dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu a {
    display: block;
    padding: .3rem 0;
    font-size: .9rem;
}

/* ---------- Hamburger (Default Hidden) ---------- */
.hamburger {
    display: none;
    position: absolute;
    right: 1.5rem;
    top: 2.8rem;
    width: 28px;
    height: 18px;
    flex-direction: column;
    justify-content: space-between;
    cursor: pointer;
    z-index: 100;
}

.hamburger span {
    display: block;
    height: 2px;
    width: 100%;
    background: #1a1a1a;
    border-radius: 2px;
    transition: all .3s ease;
}

.hamburger.active span:nth-child(1) {
    transform: translateY(8px) rotate(45deg);
}

.hamburger.active span:nth-child(2) {
    opacity: 0;
}

.hamburger.active span:nth-child(3) {
    transform: translateY(-8px) rotate(-45deg);
}

/* ---------- Mobile Menu ---------- */
.mobile-menu {
    display: none;
    flex-direction: column;
    align-items: center;
    background: #fff;
    border-top: 1px solid #eee;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.08);
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    z-index: 99;
}

.mobile-menu.open {
    display: flex;
    animation: fadeSlide .25s ease;
}

.mobile-menu a {
    padding: 0.8rem 0;
    font-size: 1rem;
}

.mobile-menu .sub {
    font-size: .85rem;
    color: #555;
}

@keyframes fadeSlide {
    from {
        opacity: 0;
        transform: translateY(-5px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ---------- Responsive (スマホ用) ---------- */
@media (max-width: 768px) {
    header {
        display: flex;
        align-items: center;
        justify-content: center;
        padding: 2rem 1rem;
    }

    header .title {
        margin: 0;
    }

    nav.pc-nav {
        display: none;
    }

    .hamburger {
        display: flex;
        position: absolute;
        right: 1.5rem;
        top: 50%;
        transform: translateY(-50%);
    }
}