/* ==============================================
 * nav.css - 主导航
 * ============================================== */

.site-nav {
    position: sticky;
    top: 0;
    z-index: var(--z-nav);
    background: var(--gradient-nav);
}

.site-nav__inner {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    height: 64px;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-6);
}

.nav-list {
    display: flex;
    align-items: center;
    gap: var(--space-8);
    height: 100%;
}

.nav-item {
    position: relative;
    height: 100%;
    display: flex;
    align-items: center;
}

.nav-link {
    display: flex;
    align-items: center;
    color: rgba(255, 255, 255, 0.92);
    font-size: var(--fs-base);
    font-weight: 500;
    letter-spacing: 1px;
    padding: 0 var(--space-2);
    height: 100%;
    transition: color var(--duration-fast) var(--ease-out);
    position: relative;
}

.nav-link::after {
    content: "";
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    bottom: 14px;
    width: 0;
    height: 3px;
    background: #fff;
    border-radius: 2px;
    transition: width var(--duration-base) var(--ease-out);
}

.nav-link:hover {
    color: #fff;
}
.nav-link:hover::after,
.nav-link.is-active::after {
    width: 28px;
}

/* 当前页指示：active  */
.nav-link.is-active {
    color: #fff;
    font-weight: 600;
}

/* 禁用链接（仅展示，不可点击） */
.nav-link--disabled {
    color: rgba(255, 255, 255, 0.5);
    cursor: default;
    user-select: none;
}
.nav-link--disabled:hover {
    color: rgba(255, 255, 255, 0.5);
}
.nav-link--disabled::after {
    display: none;
}

/* —— 移动端汉堡按钮 —— */
.nav-toggle {
    display: none;
    width: 32px;
    height: 32px;
    position: relative;
}
.nav-toggle span {
    position: absolute;
    left: 4px;
    right: 4px;
    height: 2px;
    background: #fff;
    border-radius: 2px;
    transition: transform var(--duration-base), opacity var(--duration-fast);
}
.nav-toggle span:nth-child(1) { top: 9px; }
.nav-toggle span:nth-child(2) { top: 15px; }
.nav-toggle span:nth-child(3) { top: 21px; }

@media (max-width: 900px) {
    .site-nav__inner {
        justify-content: flex-end;
        height: 56px;
    }
    .nav-list {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        background: var(--gradient-nav);
        padding: var(--space-3) 0;
        gap: 0;
        max-height: 0;
        overflow: hidden;
        transition: max-height var(--duration-base) var(--ease-in-out);
    }
    .site-nav.is-open .nav-list {
        max-height: 540px;
    }
    .nav-item {
        width: 100%;
        height: 44px;
    }
    .nav-link {
        padding: 0 var(--space-8);
        width: 100%;
    }
    .nav-link::after {
        bottom: 10px;
    }
    .nav-toggle {
        display: block;
    }
}