/* ==========================================================================
   组件：顶部导航
   首页（body.is-home）为透明叠在 Hero 之上，滚动或移动端展开后转实底
   ========================================================================== */

.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: var(--header-height);
    background-color: rgba(255, 255, 255, 0.92);
    backdrop-filter: saturate(180%) blur(14px);
    border-bottom: 1px solid var(--line);
    transition: background-color 0.3s ease, border-color 0.3s ease,
        box-shadow 0.3s ease;
}

/* 底部金线：实底状态下居中渐显，与页脚金线呼应 */
.site-header::after {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    bottom: -1px;
    height: 2px;
    background: linear-gradient(90deg, rgba(205, 164, 95, 0) 0%,
        rgba(205, 164, 95, 0.78) 50%, rgba(205, 164, 95, 0) 100%);
    opacity: 0;
    transition: opacity 0.3s ease;
    pointer-events: none;
}

body:not(.is-home) .site-header::after,
body.is-home .site-header.is-scrolled::after,
body.is-home .site-header.is-menu-open::after {
    opacity: 1;
}

.site-header__inner {
    display: flex;
    align-items: center;
    height: 100%;
    gap: 28px;
}

/* --------------------------------------------------------------------------
   品牌区
   -------------------------------------------------------------------------- */

.site-logo {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    flex-shrink: 0;
    color: var(--brand);
}

.site-logo img {
    width: 40px;
    height: 40px;
    border-radius: 10px;
}

.site-logo__text {
    font-family: var(--font-serif);
    font-size: 22px;
    font-weight: 700;
    letter-spacing: 0.06em;
    line-height: 1;
}

/* --------------------------------------------------------------------------
   主导航
   -------------------------------------------------------------------------- */

.site-nav {
    display: flex;
    align-items: center;
    gap: 34px;
    margin-left: auto;
}

.site-nav__link {
    position: relative;
    padding: 6px 0;
    font-size: 16px;
    letter-spacing: 0.04em;
    color: var(--text);
    transition: color 0.2s ease;
}

.site-nav__link::after {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    bottom: 0;
    height: 1px;
    background-color: currentColor;
    transform: scaleX(0);
    transition: transform 0.25s ease;
}

.site-nav__link:hover {
    color: var(--brand);
}

.site-nav__link:hover::after {
    transform: scaleX(1);
}

/* --------------------------------------------------------------------------
   右侧 CTA
   -------------------------------------------------------------------------- */

.site-header__cta {
    flex-shrink: 0;
    padding: 12px 28px;
    letter-spacing: 0.06em;
}

/* --------------------------------------------------------------------------
   移动端汉堡按钮
   -------------------------------------------------------------------------- */

.nav-toggle {
    display: none;
    margin-left: auto;
    width: 40px;
    height: 40px;
    border: none;
    background: transparent;
    cursor: pointer;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
}

.nav-toggle span {
    display: block;
    height: 2px;
    width: 22px;
    margin: 0 auto;
    background-color: var(--text);
    transition: transform 0.2s ease, opacity 0.2s ease;
}

.nav-toggle[aria-expanded='true'] span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.nav-toggle[aria-expanded='true'] span:nth-child(2) {
    opacity: 0;
}

.nav-toggle[aria-expanded='true'] span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* --------------------------------------------------------------------------
   首页：导航透明叠在 Hero 之上
   -------------------------------------------------------------------------- */

body.is-home {
    padding-top: 0;
}

body.is-home .site-header {
    background-color: transparent;
    border-bottom-color: transparent;
    backdrop-filter: none;
}

body.is-home .site-header .site-logo,
body.is-home .site-header .site-nav__link {
    color: #fff;
    text-shadow: 0 1px 16px rgba(20, 8, 9, 0.45);
}

body.is-home .site-header .site-nav__link:hover {
    color: var(--gold);
}

body.is-home .site-header .nav-toggle span {
    background-color: #fff;
}

body.is-home .site-header .site-header__cta {
    background-color: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.42);
    color: #fff;
    backdrop-filter: blur(6px);
}

body.is-home .site-header .site-header__cta:hover {
    background-color: rgba(255, 255, 255, 0.22);
    box-shadow: none;
}

/* 滚动后 / 移动端菜单展开后恢复浅色实底 */

body.is-home .site-header.is-scrolled,
body.is-home .site-header.is-menu-open {
    background-color: rgba(255, 252, 251, 0.96);
    border-bottom-color: var(--line);
    backdrop-filter: saturate(180%) blur(14px);
    box-shadow: 0 6px 24px rgba(36, 29, 30, 0.07);
}

body.is-home .site-header.is-scrolled .site-logo,
body.is-home .site-header.is-scrolled .site-nav__link,
body.is-home .site-header.is-menu-open .site-logo,
body.is-home .site-header.is-menu-open .site-nav__link {
    color: var(--text);
    text-shadow: none;
}

body.is-home .site-header.is-scrolled .nav-toggle span,
body.is-home .site-header.is-menu-open .nav-toggle span {
    background-color: var(--text);
}

body.is-home .site-header.is-scrolled .site-header__cta,
body.is-home .site-header.is-menu-open .site-header__cta {
    background-color: var(--brand);
    border-color: var(--brand);
    color: #fff;
    backdrop-filter: none;
}

/* --------------------------------------------------------------------------
   响应式
   -------------------------------------------------------------------------- */

@media (max-width: 768px) {
    .site-logo img {
        width: 34px;
        height: 34px;
        border-radius: 8px;
    }

    .site-logo__text {
        font-size: 19px;
        letter-spacing: 0.04em;
    }

    .site-nav {
        position: absolute;
        top: var(--header-height);
        left: 0;
        right: 0;
        flex-direction: column;
        align-items: stretch;
        gap: 0;
        margin-left: 0;
        padding: 8px 0;
        background-color: #fff;
        border-bottom: 1px solid var(--line);
        box-shadow: var(--shadow);
        display: none;
    }

    .site-nav.is-open {
        display: flex;
    }

    .site-nav__link {
        padding: 13px 24px;
        font-size: 15px;
    }

    .site-nav__link::after {
        display: none;
    }

    .nav-toggle {
        display: flex;
    }

    .site-header__cta {
        display: none;
    }
}