/* 基础变量 */
:root {
    --color-white: #ffffff;
    --color-bg-alt: #f8f9fa;
    --color-secondary: #4f585f;
    --color-menu: #304040;
    --color-menu-active: #00516f;
    --color-text: #53565b;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    color: var(--color-text);
    background-color: var(--color-white);
    line-height: 1.7;
}

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

.container {
    width: 90%;
    max-width: 1100px;
    margin: 0 auto;
}

/* 顶部导航 */
.header {
    background-color: var(--color-menu);
    color: var(--color-white);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.08);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    font-size: 1.25rem;
    font-weight: 600;
    letter-spacing: 1px;
}

.nav {
    display: flex;
    gap: 4px;
}

.nav a {
    padding: 8px 14px;
    border-radius: 4px;
    font-size: 0.95rem;
    transition: background-color 0.2s ease;
}

.nav a:hover,
.nav a:focus {
    background-color: var(--color-menu-active);
    outline: none;
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--color-white);
    font-size: 1.5rem;
    cursor: pointer;
}

/* 首页大图 */
.hero {
    position: relative;
    background: url('../images/banner.jpg') center/cover no-repeat;
    color: var(--color-white);
    padding: 120px 0 140px;
    text-align: center;
}

.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background-color: rgba(0, 81, 111, 0.55);
}

.hero .container {
    position: relative;
    z-index: 1;
}

.hero h1 {
    font-size: 2.2rem;
    font-weight: 600;
    margin-bottom: 16px;
    letter-spacing: 1px;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.25);
}

.hero p {
    font-size: 1.15rem;
    margin-bottom: 32px;
    opacity: 0.95;
    text-shadow: 0 1px 3px rgba(0, 0, 0, 0.25);
}

.btn {
    display: inline-block;
    background-color: var(--color-white);
    color: var(--color-menu-active);
    padding: 12px 32px;
    border-radius: 4px;
    font-weight: 500;
    transition: opacity 0.2s ease, transform 0.2s ease;
}

.btn:hover,
.btn:focus {
    opacity: 0.92;
    transform: translateY(-1px);
}

/* 通用区块 */
.section {
    padding: 72px 0;
}

.section-alt {
    background-color: var(--color-bg-alt);
}

.section h2 {
    font-size: 1.75rem;
    color: var(--color-menu);
    margin-bottom: 28px;
    text-align: center;
}

.section > .container > p {
    max-width: 760px;
    margin: 0 auto;
    text-align: center;
    font-size: 1.05rem;
}

/* 区块配图 */
.section-img {
    display: block;
    width: 100%;
    max-width: 760px;
    height: auto;
    margin: 0 auto 36px;
    border-radius: 6px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
}

/* 关于我们图文 */
.about-row {
    display: flex;
    align-items: center;
    gap: 40px;
    max-width: 960px;
    margin: 36px auto 0;
}

.about-img {
    width: 45%;
    max-width: 400px;
    height: auto;
    border-radius: 6px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
}

.about-row p {
    flex: 1;
    font-size: 1.05rem;
    text-align: left;
    line-height: 1.8;
}

/* 卡片 */
.cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 24px;
    margin-top: 36px;
}

.card {
    background-color: var(--color-white);
    border: 1px solid #e5e7eb;
    border-radius: 6px;
    padding: 28px;
    transition: box-shadow 0.2s ease, transform 0.2s ease;
}

.card:hover {
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.06);
    transform: translateY(-2px);
}

.card h3 {
    font-size: 1.15rem;
    color: var(--color-menu-active);
    margin-bottom: 12px;
}

.card p {
    font-size: 0.95rem;
    color: var(--color-text);
}

/* 解决方案列表 */
.solution-list {
    list-style: none;
    max-width: 760px;
    margin: 36px auto 0;
}

.solution-list li {
    padding: 18px 0;
    border-bottom: 1px solid #e5e7eb;
    font-size: 1.05rem;
}

.solution-list li:last-child {
    border-bottom: none;
}

.solution-list strong {
    color: var(--color-menu-active);
    font-weight: 600;
}

/* 联系信息 */
.contact-info {
    max-width: 500px;
    margin: 36px auto 0;
    text-align: center;
}

.contact-info p {
    margin-bottom: 10px;
    font-size: 1.05rem;
}

.contact-info span {
    color: var(--color-secondary);
    font-weight: 500;
}

/* 页脚 */
.footer {
    background-color: var(--color-menu);
    color: var(--color-white);
    padding: 24px 0;
    text-align: center;
    font-size: 0.9rem;
}

.footer .icp {
    margin-top: 8px;
    font-size: 0.85rem;
}

.footer .icp a {
    color: rgba(255, 255, 255, 0.8);
    transition: color 0.2s ease;
}

.footer .icp a:hover,
.footer .icp a:focus {
    color: var(--color-white);
}

/* 响应式 */
@media (max-width: 768px) {
    .menu-toggle {
        display: block;
    }

    .nav {
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        flex-direction: column;
        background-color: var(--color-menu);
        padding: 8px 0 16px;
        display: none;
        box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    }

    .nav.open {
        display: flex;
    }

    .nav a {
        padding: 12px 5%;
        border-radius: 0;
    }

    .hero {
        padding: 72px 0 88px;
    }

    .hero h1 {
        font-size: 1.7rem;
    }

    .section {
        padding: 52px 0;
    }

    .section-img {
        margin-bottom: 28px;
    }

    .about-row {
        flex-direction: column;
        gap: 24px;
    }

    .about-img {
        width: 100%;
        max-width: 100%;
    }

    .about-row p {
        text-align: center;
    }
}