/* 基础样式：工业风核心基调 */
:root {
    --industrial-blue: #1E88E5; /* 工业蓝主色 */
    --dark-gray: #2C3E50; /* 深灰背景 */
    --light-gray: #F5F5F5; /* 浅灰背景 */
    --metal-silver: #E0E0E0; /* 金属银 */
    --text-dark: #333333; /* 文字深色 */
    --text-light: #FFFFFF; /* 文字浅色 */
    --shadow: 0 4px 12px rgba(0,0,0,0.1); /* 基础阴影 */
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Montserrat', '思源黑体', sans-serif;
}

body {
    background-color: var(--light-gray);
    color: var(--text-dark);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color 0.3s;
}

/* 1. 导航栏样式优化 */
.navbar {
    background-color: var(--dark-gray);
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
    transition: all 0.3s ease;
}

.navbar-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.navbar-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text-light);
}

.navbar-brand i {
    color: var(--industrial-blue);
    font-size: 1.6rem;
}

.navbar-toggler {
    display: none;
    background: none;
    border: none;
    color: var(--text-light);
    font-size: 1.5rem;
    cursor: pointer;
}

.navbar-nav {
    display: flex;
    gap: 30px;
    list-style: none;
}

.nav-link {
    color: var(--metal-silver);
    font-weight: 500;
    position: relative;
    padding: 5px 0;
}

.nav-link:hover {
    color: var(--industrial-blue);
}

.nav-link::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 0;
    height: 2px;
    background-color: var(--industrial-blue);
    transition: width 0.3s;
}

.nav-link:hover::after {
    width: 100%;
}

/* 滚动时导航栏变化 */
.navbar.scrolled {
    padding: 10px 0;
    background-color: rgba(44, 62, 80, 0.95);
    box-shadow: 0 4px 15px rgba(0,0,0,0.25);
}


/* 2. 主内容区基础样式 */
main {
    flex: 1;
}

/* 按钮基础样式（全局通用） */
.btn {
    display: inline-block;
    background-color: var(--industrial-blue);
    color: var(--text-light);
    border: none;
    padding: 10px 24px;
    border-radius: 4px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn:hover {
    background-color: #1565C0;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.15);
}

.btn-outline {
    background-color: transparent;
    border: 2px solid var(--industrial-blue);
    color: var(--industrial-blue);
}

.btn-outline:hover {
    background-color: var(--industrial-blue);
    color: var(--text-light);
}


/* 3. 页脚样式优化 */
.footer {
    background-color: var(--dark-gray);
    color: var(--metal-silver);
    padding: 60px 0 30px;
    margin-top: 80px;
}

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

.footer-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
}

.footer-col h5 {
    color: var(--text-light);
    font-size: 1.2rem;
    margin-bottom: 25px;
    position: relative;
    padding-bottom: 10px;
}

.footer-col h5::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 40px;
    height: 2px;
    background-color: var(--industrial-blue);
}

.footer-col p {
    margin-bottom: 15px;
    line-height: 1.7;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 12px;
}

.footer-links a:hover {
    color: var(--industrial-blue);
    padding-left: 5px;
}

.footer-contact p {
    display: flex;
    align-items: center;
    gap: 10px;
}

.footer-contact i {
    color: var(--industrial-blue);
    width: 20px;
}

.footer-bottom {
    margin-top: 50px;
    padding-top: 20px;
    border-top: 1px solid rgba(255,255,255,0.1);
    text-align: center;
    font-size: 0.9rem;
}


/* 4. 响应式适配 */
@media (max-width: 768px) {
    .navbar-toggler {
        display: block;
    }

    .navbar-nav {
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: var(--dark-gray);
        flex-direction: column;
        gap: 0;
        padding: 20px 0;
        box-shadow: 0 10px 10px rgba(0,0,0,0.2);
        transform: translateY(-100%);
        opacity: 0;
        pointer-events: none;
        transition: all 0.3s ease;
    }

    .navbar-nav.active {
        transform: translateY(0);
        opacity: 1;
        pointer-events: auto;
    }

    .navbar-nav li {
        padding: 0 20px;
    }

    .nav-link {
        display: block;
        padding: 12px 0;
    }
}