/* ============================================
   公共样式 — 头部、底部、重置、设计 token
   所有页面共享
   ============================================ */

/* ---- 重置与基础 ---- */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* 颜色 */
    --color-brand-gold: #DBAE75;
    --color-deep-navy: #192431;
    --color-card-navy: #27313E;
    --color-bg: #F7F8FA;
    --color-white: #FFFFFF;
    --color-text: #333333;
    --color-text-soft: #999999;
    --color-footer-text: #C9CDD4;
    --color-divider: #86909C;
    --color-overlay-dark: rgba(25, 36, 49, 0.5);
    --color-overlay-darker: rgba(25, 36, 49, 0.7);
    --color-overlay-light: rgba(25, 36, 49, 0.4);
    --color-placeholder: #D9D9D9;

    /* 尺寸 */
    --container-max: 1920px;
    --container-side: 72px;
    --section-side: 80px;
    --radius-card: 12px;
    --radius-btn: 8px;

    /* 字体 */
    --font-cn: 'PingFang SC', 'Microsoft YaHei', -apple-system, BlinkMacSystemFont, sans-serif;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-cn);
    color: var(--color-text);
    background: var(--color-bg);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

img {
    max-width: 100%;
    display: block;
}

a {
    color: inherit;
    text-decoration: none;
}

ul,
ol {
    list-style: none;
}

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

/* ============================================
   顶部导航
   ============================================ */
.site-header {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 72px;
    background: var(--color-overlay-light);
    z-index: 100;
}

.header-inner {
    max-width: var(--container-max);
    height: 100%;
    margin: 0 auto;
    padding: 0 var(--container-side);
    display: flex;
    align-items: center;
    position: relative;
    justify-content: center;
}

.logo {
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    display: flex;
    align-items: center;
    height: 36px;
}

.logo img {
    height: 36px;
    width: auto;
}

.main-nav {
    display: flex;
    gap: 100px;
    align-items: center;
}

.nav-item {
    position: relative;
    font-size: 14px;
    color: var(--color-white);
    padding-bottom: 4px;
    transition: color 0.2s;
}

.nav-item:hover,
.nav-item.is-active {
    color: var(--color-brand-gold);
}

.nav-item.is-active::after {
    content: '';
    position: absolute;
    left: 50%;
    bottom: -14px;
    transform: translateX(-50%);
    width: 24px;
    height: 2px;
    background: var(--color-brand-gold);
}

.menu-toggle {
    display: none;
}

/* ============================================
   页脚
   ============================================ */
.site-footer {
    background: var(--color-deep-navy);
    color: var(--color-footer-text);
    padding: 80px var(--container-side) 30px;
}

.footer-inner {
    max-width: 1000px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 50px;
}

.footer-title {
    color: var(--color-white);
    font-size: 14px;
    font-weight: 400;
    margin-bottom: 30px;
    line-height: 1.4;
}

.footer-list li {
    margin-bottom: 14px;
}

.footer-list a {
    color: var(--color-footer-text);
    font-size: 12px;
    line-height: 1.4;
    transition: color 0.2s;
    display: flex;
    align-items: center;
    gap: 6px;
}

.footer-list a::before {
    content: '';
    display: inline-block;
    width: 4px;
    height: 4px;
    border-radius: 50%;
    background: var(--color-footer-text);
    flex-shrink: 0;
}

.footer-list a:hover {
    color: var(--color-brand-gold);
}

.footer-divider {
    max-width: 1000px;
    margin: 30px auto 16px;
    border: 0;
    border-top: 1px solid var(--color-divider);
}

.footer-meta {
    max-width: 1000px;
    margin: 0 auto;
    text-align: center;
    font-size: 12px;
    line-height: 1.4;
    color: var(--color-footer-text);
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
}

.footer-meta p {
    margin-bottom: 4px;
}

.footer-meta a {
    color: var(--color-footer-text);
    transition: color 0.2s;
    text-decoration: underline;
}

.footer-meta a:hover {
    color: var(--color-brand-gold);
}

/* ============================================
   响应式 - 头尾
   ============================================ */

/* 平板 (≤ 1200px) */
@media (max-width: 1200px) {
    :root {
        --container-side: 32px;
        --section-side: 32px;
    }

    .main-nav {
        gap: 56px;
    }

    .footer-inner {
        gap: 32px;
    }
}

/* 手机 (≤ 768px) */
@media (max-width: 768px) {
    :root {
        --container-side: 20px;
        --section-side: 20px;
    }

    .site-header {
        height: 56px;
    }

    .header-inner {
        padding: 0 var(--container-side);
    }

    .main-nav {
        display: none;
        position: absolute;
        top: 56px;
        left: 0;
        right: 0;
        flex-direction: column;
        background: var(--color-deep-navy);
        gap: 0;
        padding: 12px 0;
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
    }

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

    .nav-item {
        padding: 14px 24px;
        width: 100%;
        text-align: center;
    }

    .nav-item.is-active::after {
        display: none;
    }

    .menu-toggle {
        display: flex;
        align-items: center;
        justify-content: center;
        width: 36px;
        height: 36px;
        color: var(--color-white);
        font-size: 22px;
        position: absolute;
        right: 20px;
        top: 50%;
        transform: translateY(-50%);
    }

    .site-footer {
        padding: 40px var(--container-side) 24px;
    }

    .footer-inner {
        grid-template-columns: 1fr 1fr;
        gap: 28px 20px;
    }

    .footer-title {
        margin-bottom: 14px;
    }

    .footer-divider {
        margin: 24px auto 12px;
    }

    .footer-meta {
        font-size: 11px;
    }

    .footer-meta p {
        line-height: 1.6;
    }
}

/* 超小屏 (≤ 480px) */
@media (max-width: 480px) {
    .footer-inner {
        grid-template-columns: 1fr;
    }
}

/* ============================================
   回到顶部按钮
   ============================================ */
.back-to-top {
    position: fixed;
    bottom: 40px;
    right: 40px;
    width: 50px;
    height: 50px;
    background: var(--color-brand-gold);
    color: var(--color-white);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s, visibility 0.3s;
    z-index: 1000;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background: #c49a65;
}

@media (max-width: 768px) {
    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 44px;
        height: 44px;
        font-size: 18px;
    }
}