/* ============================================================
   全局重置与基础样式
   ============================================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Microsoft Yahei", "PingFang SC", Arial, sans-serif;
}

body {
    background-color: #f5f8ff;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 5%;
    flex: 1;
}

/* ============================================================
   导航栏
   ============================================================ */
header {
    background: #fff;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
    position: sticky;
    top: 0;
    z-index: 999;
}

.navbar-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 75px;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 12px;
    color: #212529;
    text-decoration: none;
    font-weight: 700;
    font-size: clamp(1.1rem, 2vw, 1.3rem);
}

.nav-brand img {
    height: clamp(2.2rem, 4vw, 3.2rem);
}

.menu-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    z-index: 1000;
}

.bar {
    width: 24px;
    height: 2.5px;
    background-color: #333;
    margin: 3px 0;
    transition: 0.3s;
    border-radius: 3px;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-links a {
    color: #495057;
    text-decoration: none;
    font-size: clamp(0.9rem, 1.5vw, 1.05rem);
    position: relative;
    padding: 0.5rem 0;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: #007bff;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: #007bff;
    transition: width 0.3s ease;
}

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

/* ============================================================
   Banner
   ============================================================ */
.header-banner {
    padding: 40px 20px;
    text-align: center;
    margin-bottom: 24px;
}

.banner-title {
    font-size: 32px;
    font-weight: 700;
    color: #1a73e8;
    margin: 0 0 12px;
    line-height: 1.3;
}

.banner-subtitle {
    font-size: 16px;
    color: #475569;
    margin: 0 0 16px;
    line-height: 1.6;
    font-weight: 500;
}

.banner-desc {
    font-size: 15px;
    color: #64748b;
    max-width: 720px;
    margin: 0 auto;
    line-height: 1.7;
}

@media (max-width: 640px) {
    .header-banner {
        padding: 24px 16px;
    }
    .banner-title {
        font-size: 20px;
        margin-bottom: 8px;
    }
    .banner-subtitle {
        font-size: 13px;
        line-height: 1.7;
    }
    .banner-desc {
        font-size: 13px;
        text-align: left;
    }
}

/* ============================================================
   卡片容器：PC 两列，平板/手机一列
   ============================================================ */
.card-container {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
    margin-bottom: 3rem;
}

.card-group {
    background: #fff;
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
    border: 1px solid #e8f1ff;
    min-width: 0;
}

.card-group:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.08);
    border-color: #d1e7ff;
}

.card-title {
    font-size: clamp(1.2rem, 2vw, 1.5rem);
    margin-bottom: 1.8rem;
    color: #212529;
    display: flex;
    align-items: center;
    gap: 12px;
    padding-bottom: 1rem;
    border-bottom: 2px solid #007bff;
    font-weight: 600;
}

.card-title i {
    color: #007bff;
    font-size: 1.4rem;
}

.card-items {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
}

.card-item {
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 1.1rem 0.8rem;
    background: #fafdff;
    border: 1px solid #e8f1ff;
    border-radius: 8px;
    text-decoration: none;
    color: #495057;
    transition: all 0.3s ease;
    font-size: clamp(0.9rem, 1.5vw, 1.05rem);
    position: relative;
    overflow: hidden;
}

.card-item:hover {
    border-color: #007bff;
    color: #007bff;
    background-color: #eaf5ff;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 123, 255, 0.1);
}

.card-item::before {
    content: "\f0eb";
    font-family: "Font Awesome 6 Free";
    font-weight: 900;
    position: absolute;
    top: 8px;
    right: 8px;
    font-size: 0.6rem;
    color: #007bff;
    opacity: 0;
    transition: opacity 0.3s;
}

.card-item:hover::before {
    opacity: 0.7;
}

/* ============================================================
   响应式：平板 / 手机
   ============================================================ */
@media (max-width: 1024px) {
    .card-container {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    .card-items {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 768px) {
    .navbar-container {
        height: 70px;
        position: relative;
    }
    .menu-toggle {
        display: flex;
    }
    .nav-links {
        position: fixed;
        top: 0;
        right: -100%;
        height: 100vh;
        width: 220px;
        background-color: #fff;
        flex-direction: column;
        justify-content: center;
        padding: 2rem;
        gap: 2rem;
        box-shadow: -2px 0 15px rgba(0, 0, 0, 0.1);
        transition: 0.3s ease;
        z-index: 999;
    }
    .nav-links.active {
        right: 0;
    }
    .nav-links a {
        font-size: 1rem;
        padding: 0.8rem 1rem;
        width: 100%;
        text-align: left;
        border-radius: 6px;
    }
    .nav-links a:hover {
        background-color: #f5f8ff;
    }
    .card-group {
        padding: 1.5rem;
    }
    .header-banner {
        padding: 2rem 0;
    }
}

@media (max-width: 480px) {
    .card-container {
        gap: 1.2rem;
    }
    .card-items {
        grid-template-columns: repeat(2, 1fr);
        gap: 0.9rem;
    }
    .card-item {
        padding: 0.9rem 0.6rem;
        font-size: 0.85rem;
    }
    .banner-title {
        font-size: clamp(1.3rem, 3vw, 1.8rem);
    }
}

/* ============================================================
   SEO 介绍区
   ============================================================ */
.intro-section {
    margin: 40px 0;
    padding: 8px 0;
    color: #475569;
    font-size: 15px;
    line-height: 1.85;
}

.intro-section h2 {
    font-size: 1.25rem;
    color: #1a73e8;
    margin-bottom: 14px;
    font-weight: 600;
}

.intro-section p {
    margin-bottom: 12px;
}

.intro-section p:last-child {
    margin-bottom: 0;
}

.intro-section strong {
    color: #1a73e8;
    font-weight: 500;
}

.intro-section a {
    color: #1a73e8;
    text-decoration: underline;
}

@media (max-width: 640px) {
    .intro-section {
        padding: 8px 0;
        margin: 24px 0;
        font-size: 14px;
        line-height: 1.8;
    }
    .intro-section h2 {
        font-size: 1.05rem;
    }
}

/* ============================================================
   友情链接（纯文字，无卡片）
   ============================================================ */
.friend-links-section {
    margin: 0 0 2rem;
    padding: 0;
    background: transparent;
    border: none;
    box-shadow: none;
    text-align: center;
}

.friend-links-title {
    font-size: 0.95rem;
    color: #6c757d;
    font-weight: 500;
    margin-bottom: 0.8rem;
}

.friend-links-title i {
    color: #1a73e8;
    margin-right: 4px;
}

.friend-links {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.5rem 1.5rem;
}

.friend-links a {
    color: #6c757d;
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.25s ease;
}

.friend-links a:hover {
    color: #1a73e8;
}

@media (max-width: 640px) {
    .friend-links {
        gap: 0.4rem 1rem;
    }
    .friend-links a {
        font-size: 0.85rem;
    }
}

/* ============================================================
   页脚
   ============================================================ */
footer {
    text-align: center;
    padding: 2.5rem 5%;
    color: #6c757d;
    background-color: #fff;
    border-top: 1px solid #e8f1ff;
    margin-top: auto;
}

footer .footer-title {
    font-size: 1.1rem;
    color: #212529;
    margin-bottom: 1rem;
    font-weight: 600;
}

footer .footer-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 1.2rem;
    flex-wrap: wrap;
}

footer .footer-links a {
    color: #6c757d;
    text-decoration: none;
    transition: color 0.3s;
}

footer .footer-links a:hover {
    color: #007bff;
}

footer .copyright {
    font-size: clamp(0.85rem, 1.5vw, 0.95rem);
    margin-top: 1rem;
}