/* 重置默认样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* 基础样式 */
:root {
    /* 颜色 */
    --text-color: #1d1d1f;
    --text-color-secondary: #86868b;
    --link-color: #0066cc;
    --primary-color: #0066cc;
    --primary-color-dark: #0051d5;
    --border-color: #d2d2d7;
    --background-color: #f5f5f7;
    --background-hover: #f5f5f7;
    --color-primary: #0066cc;
    --color-primary-rgb: 0, 102, 204;
    --color-success: #34c759;
    --color-danger: #ff3b30;
    --text-primary: #1d1d1f;
    --text-secondary: #86868b;
    --card-background-color: rgba(255, 255, 255, 0.8);
    --card-shadow: 0 8px 16px rgba(0, 0, 0, 0.04);
    --card-border-radius: 12px;
    --modal-background: rgba(255, 255, 255, 0.72);

    /* 圆角 */
    --border-radius-small: 6px;
    --border-radius-base: 8px;
    --border-radius-large: 12px;
    --border-radius-xlarge: 16px;
    --border-radius-full: 9999px;

    /* 字体 */
    --font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
    --font-size-base: 17px;
    --font-size-small: 14px;
    --font-size-large: 20px;
    --line-height-base: 1.47059;

    /* 布局尺寸 */
    --spacing-base: 16px;
    --spacing-large: 24px;
    --header-height: 44px;
    --footer-height: 60px;
    --content-width: 1200px;

    /* 动画 */
    --transition-base: 0.3s ease;
    --transition-fast: 0.2s ease;
    --transition-slow: 0.4s ease;
}

/* 确保页面至少占满整个视口高度 */
html, body {
    height: 100%;
    margin: 0;
    padding: 0;
}

body {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background-color: var(--background-color);
    color: var(--text-color);
}

/* 主要内容区域 */
main {
    flex: 1;
    padding-bottom: 120px; /* 为固定定位的页脚留出空间 */
}

/* Hero 区域 */
.hero {
    background-color: #fafafa;
    color: var(--primary-color);
    text-align: center;
    padding: 120px 20px;
    margin-bottom: 40px;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 56px;
    font-weight: 600;
    margin-bottom: 20px;
    background: linear-gradient(90deg, #1d1d1f 0%, #434344 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero h2 {
    font-size: 28px;
    font-weight: 400;
    margin-bottom: 15px;
    color: var(--primary-color);
}

.hero p {
    font-size: 21px;
    color: var(--secondary-color);
}

/* 特性区域 */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    padding: 60px 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.feature-item {
    text-align: center;
    padding: 30px;
}

.feature-item h3 {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 15px;
}

.feature-item p {
    font-size: 17px;
    color: var(--secondary-color);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 40px;
    }

    .hero h2 {
        font-size: 24px;
    }

    .hero p {
        font-size: 18px;
    }

    .features {
        grid-template-columns: 1fr;
        padding: 40px 20px;
    }
}

/* 通用动画 */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-content, .feature-item {
    animation: fadeIn 1s ease-out forwards;
}

input, button {
    font-family: inherit;
    font-size: inherit;
    line-height: inherit;
}

/* 模态框样式 */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
    z-index: 1000;
}

.modal-overlay.show {
    opacity: 1;
    visibility: visible;
}

.modal-container {
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    width: 90%;
    max-width: 500px;
    max-height: 80vh;
    overflow-y: auto;
    transform: scale(0.9);
    opacity: 0;
    transition: transform 0.3s ease, opacity 0.3s ease;
}

.modal-overlay.show .modal-container {
    transform: scale(1);
    opacity: 1;
}

.modal-header {
    padding: 16px;
    border-bottom: 1px solid #e0e0e0;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-title {
    margin: 0;
    font-size: 18px;
    color: #333;
}

.modal-body {
    padding: 16px;
}

.modal-footer {
    padding: 16px;
    border-top: 1px solid #e0e0e0;
    display: flex;
    justify-content: flex-end;
    gap: 12px;
}

.modal-footer .btn {
    padding: 8px 16px;
    border-radius: 4px;
    font-size: 14px;
    cursor: pointer;
}

.modal-footer .btn-secondary {
    background-color: #f0f0f0;
    color: #333;
    border: 1px solid #d0d0d0;
}

.modal-footer .btn-primary {
    background-color: #007aff;
    color: white;
    border: none;
}