/* ===== CSS Variables - 黑红白 + 圆角风格 ===== */
:root {
    --primary-bg: #000000;        /* 主背景：纯黑 */
    --secondary-bg: #111111;      /* 次级背景：深黑 */
    --accent-red: #FF003C;        /* 主强调色：鲜艳红 */
    --accent-red-light: #FF3366;  /* 悬停色：亮红 */
    --accent-neutral: #444444;    /* 中性强调色：中灰 */
    --text-primary: #FFFFFF;      /* 主文字：纯白 */
    --text-secondary: #CCCCCC;    /* 次级文字：浅灰 */
    --text-light: #999999;        /* 辅助文字：中灰 */
    --border-color: #333333;      /* 边框/分割线：深灰 */
    --shadow-subtle: 0 8px 30px rgba(255, 0, 60, 0.15); /* 红色阴影 */
    --shadow-card: 0 10px 30px rgba(0, 0, 0, 0.6);
    --transition: all 0.3s ease;
    --section-padding: 100px 0;
    --border-radius: 12px;        /* 圆角大小 */
    --btn-border-radius: 50px;    /* 按钮圆角 */
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background-color: var(--primary-bg);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}


/* ===== 下拉菜单样式 ===== */
.dropdown {
    position: relative;
}

.dropdown > a {
    display: flex;
    align-items: center;
    justify-content: center;
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 220px;
    background-color: rgba(0, 0, 0, 0.98);
    backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    border-top: 2px solid var(--accent-red);
    list-style: none;
    padding: 15px 0;
    margin-top: 20px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all 0.3s ease;
    z-index: 1001;
    border-radius: 8px;
    box-shadow: var(--shadow-card);
}

/* 桌面端悬停效果 */
@media (min-width: 901px) {
    .dropdown:hover .dropdown-menu {
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
    }
}

.dropdown-menu li {
    margin: 0;
    padding: 0;
}

.dropdown-menu a {
    display: block;
    padding: 12px 25px;
    font-size: 0.9rem;
    color: var(--text-secondary);
    transition: all 0.3s ease;
    border-left: 2px solid transparent;
}

.dropdown-menu a:hover {
    color: var(--text-primary);
    background-color: rgba(255, 0, 60, 0.05);
    border-left: 2px solid var(--accent-red);
    padding-left: 30px;
}

/* 移动端下拉菜单调整 */
@media (max-width: 900px) {
    .dropdown > a {
        justify-content: center;
    }

    .dropdown-menu {
        position: static;
        background-color: transparent;
        border: none;
        border-left: 2px solid rgba(255, 0, 60, 0.3);
        margin: 5px 0 5px 10px;
        padding: 0px 0;
        opacity: 1;
        visibility: visible;
        transform: none;
        display: none;
        min-width: auto;
        width: calc(100%);
        box-shadow: none;
        transition: none;
    }

    .dropdown.active .dropdown-menu {
        display: block;
    }

    .dropdown-menu a {
        padding: 5px 10px;
        border-left: none;
    }

    .dropdown-menu a:hover {
        border-left: none;
        padding-left: 10px;
    }

    /* 修复导航链接间距 */
    .nav-links li {
        margin: 5px 0;
    }
}

/* 修复桌面端导航链接间距 */
@media (min-width: 901px) {
    .nav-links li {
        margin-left: 30px;
    }
}