/* ==================== 基础重置与变量 ==================== */
:root {
    --primary: #1890ff;
    --primary-dark: #0c7bdb;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-600: #475569;
    --gray-800: #1e293b;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --radius-lg: 1rem;
    --radius-md: 0.75rem;
}

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

body {
    font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif;
    background: linear-gradient(135deg, var(--gray-50) 0%, var(--gray-100) 100%);
    color: var(--gray-800);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    /* 垂直排列子元素 */
    padding: 2rem 1rem;
}

.container {
    max-width: 1200px;
    width: 100%;
    margin: 0 auto;
    flex: 1;
    /* 占据剩余空间，将 footer 推到底部 */
}

/* ==================== 头部 ==================== */
.hero {
    text-align: center;
    margin-bottom: 3rem;
}

h1 {
    font-size: 2.5rem;
    font-weight: 600;
    background: linear-gradient(135deg, var(--primary), #5c6bc0);
    background-clip: text;
    -webkit-background-clip: text;
    color: transparent;
    margin-bottom: 0.5rem;
    letter-spacing: -0.02em;
}

.subtitle {
    font-size: 1.125rem;
    color: var(--gray-600);
    max-width: 600px;
    margin: 0 auto;
}

/* ==================== 卡片网格 ==================== */
.card-grid {
    display: grid;
    gap: 2rem;
    /* 默认手机单列 */
    grid-template-columns: 1fr;
}

/* 平板及以上：两列 */
@media (min-width: 768px) {
    .card-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* 超大屏幕：三列（可选） */
@media (min-width: 1400px) {
    .card-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

.card {
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(2px);
    border-radius: var(--radius-lg);
    padding: 1.75rem;
    box-shadow: var(--shadow-md);
    transition: all 0.25s ease;
    border: 1px solid rgba(255, 255, 255, 0.8);
    text-align: center;
    backdrop-filter: blur(4px);
}

.card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
    background: white;
}

.card-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.card h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--gray-800);
}

.card p {
    font-size: 0.95rem;
    color: var(--gray-600);
    margin-bottom: 1.5rem;
    line-height: 1.5;
}

.btn {
    display: inline-block;
    background: var(--primary);
    color: white;
    text-decoration: none;
    padding: 0.6rem 1.5rem;
    border-radius: 2rem;
    font-weight: 500;
    font-size: 0.9rem;
    transition: all 0.2s;
    border: none;
    cursor: pointer;
}

.btn:hover {
    background: var(--primary-dark);
    transform: scale(0.98);
    box-shadow: var(--shadow-sm);
}

/* ==================== 页脚 ==================== */
.footer {
    text-align: center;
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--gray-200);
    font-size: 0.8rem;
    color: var(--gray-600);
    max-width: 1200px;
    width: 100%;
    margin-left: auto;
    margin-right: auto;
}

/* ==================== 移动端适配 ==================== */
@media (max-width: 640px) {
    body {
        padding: 1rem;
    }

    h1 {
        font-size: 1.8rem;
    }

    .subtitle {
        font-size: 1rem;
    }

    .card-grid {
        gap: 1rem;
    }

    .card {
        padding: 1.25rem;
    }

    .card h3 {
        font-size: 1.25rem;
    }

    .btn {
        padding: 0.5rem 1.25rem;
    }
}

/* 可选：暗色模式支持（简单示例） */
@media (prefers-color-scheme: dark) {
    :root {
        --gray-50: #0f172a;
        --gray-100: #1e293b;
        --gray-200: #334155;
        --gray-600: #94a3b8;
        --gray-800: #e2e8f0;
    }

    body {
        background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
    }

    .card {
        background: rgba(30, 41, 59, 0.85);
        border-color: rgba(51, 65, 85, 0.5);
    }

    .card:hover {
        background: #1e293b;
        border-color: var(--primary);
    }

    .btn {
        background: var(--primary);
    }
}

/* ==================== 卡片左右布局 ==================== */
.card-horizontal {
    display: flex;
    flex-direction: row;
    align-items: center;
    gap: 1.5rem;
    text-align: left;
    padding: 1rem;
    height: 100%;
}

.card-image {
    flex-shrink: 0;
    width: 120px;
    height: 120px;
    border-radius: 12px;
    overflow: hidden;
    background: #f0f2f5;
}

.card-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.card-content {
    flex: 1;
}

/* 手机端恢复上下布局 */
@media (max-width: 640px) {
    .card-horizontal {
        flex-direction: column;
        text-align: center;
    }

    .card-image {
        width: 100%;
        max-width: 200px;
        height: auto;
        aspect-ratio: 1 / 1;
    }
}

.card-content h3 {
    margin: 0 0 0.5rem 0;
    font-size: 1.25rem;
}

.card-content p {
    margin: 0 0 1rem 0;
}