/* =========================================
   1. 全局变量与重置 (Global & Reset)
   ========================================= */
:root {
    --primary-color: #007bff;       /* 主色调：科技蓝 */
    --primary-hover: #0056b3;       /* 按钮悬停色 */
    --bg-color: #f8f9fa;            /* 全局背景灰白 */
    --white: #ffffff;
    --text-color: #333333;          /* 正文黑 */
    --text-light: #6c757d;          /* 辅助灰 */
    --footer-bg: #2c3e50;           /* 页脚深蓝灰 */
    --footer-text: #ecf0f1;         /* 页脚文字白 */

    --border-radius: 8px;
    --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color 0.2s;
}

/* =========================================
   2. 导航栏 (Header & Nav)
   ========================================= */
header {
    background-color: var(--white);
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
}

nav {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    margin-right: 2rem;
}

.menu {
    display: flex;
    gap: 20px;
    align-items: center;
}

.menu a:hover {
    color: var(--primary-color);
}

/* --- 语言选择器 (原生美化版) --- */
.lang-select-wrapper {
    display: flex;
    align-items: center;
    margin-left: 20px;
    padding: 5px;
    border: 1px solid #dee2e6;
    border-radius: 20px; /* 圆角药丸形状 */
    background-color: #fff;
    transition: border-color 0.2s;
}

.lang-select-wrapper:hover {
    border-color: var(--primary-color);
}

.lang-icon {
    width: 18px;
    height: 18px;
    color: #666;
    margin-left: 5px;
    margin-right: 2px;
}

.lang-select-wrapper select {
    background-color: transparent;
    border: none;
    padding: 4px 8px;
    font-size: 14px;
    color: #333;
    cursor: pointer;
    outline: none;
    font-family: inherit;
}

/* =========================================
   3. 主内容区域 (Main & Upload)
   ========================================= */
main {
    flex: 1;
    width: 100%;
    max-width: 1000px;
    margin: 0 auto;
    padding: 3rem 1rem;
    text-align: center;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: #2c3e50;
}

.hero p {
    font-size: 1.1rem;
    color: var(--text-light);
    margin-bottom: 2rem;
}

/* --- 上传框核心样式 --- */
.upload-area {
    background-color: var(--white);
    border: 2px dashed #cbd5e0;
    border-radius: var(--border-radius);
    padding: 4rem 2rem;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-bottom: 1rem;
    position: relative;
}

.upload-area:hover {
    border-color: var(--primary-color);
    background-color: #f0f7ff;
}

.upload-area button {
    background-color: var(--primary-color);
    color: var(--white);
    border: none;
    padding: 12px 30px;
    font-size: 1.1rem;
    border-radius: 50px;
    cursor: pointer;
    transition: background-color 0.3s;
    font-weight: 600;
}

.upload-area button:hover {
    background-color: var(--primary-hover);
}

/* =========================================
   4. 进度条样式 (Progress Bar)
   ========================================= */
.progress-bar-bg {
    width: 100%;
    height: 10px;
    background-color: #e9ecef;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: inset 0 1px 2px rgba(0,0,0,0.1);
}

.progress-fill {
    height: 100%;
    background-color: var(--primary-color);
    /* 条纹背景效果 */
    background-image: linear-gradient(45deg,rgba(255,255,255,.15) 25%,transparent 25%,transparent 50%,rgba(255,255,255,.15) 50%,rgba(255,255,255,.15) 75%,transparent 75%,transparent);
    background-size: 1rem 1rem;
    transition: width 0.3s ease;
}

/* 进度条动画 (上传完成后显示) */
.progress-fill.active {
    animation: progress-bar-stripes 1s linear infinite;
}

@keyframes progress-bar-stripes {
    0% { background-position: 1rem 0; }
    100% { background-position: 0 0; }
}

/* =========================================
   5. SEO 文章内容区域
   ========================================= */
.seo-content {
    text-align: left;
    background: var(--white);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    margin-top: 3rem;
}

.seo-content h2 {
    font-size: 1.8rem;
    margin-bottom: 1rem;
    color: #2c3e50;
    border-bottom: 2px solid #f0f0f0;
    padding-bottom: 10px;
}

.seo-content p {
    margin-bottom: 1rem;
    color: #4a4a4a;
}

/* =========================================
   6. 页脚 (Footer) - 深色版
   ========================================= */
footer {
    background-color: var(--footer-bg); /* 深色背景 #2c3e50 */
    color: var(--footer-text);          /* 浅色文字 #ecf0f1 */
    text-align: center;
    padding: 40px 0 20px;
    margin-top: auto;
}

.footer-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 页脚链接组 */
.footer-links {
    margin-bottom: 25px;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 25px;
}

.footer-links a {
    color: #bdc3c7; /* 浅灰，防止太白刺眼 */
    text-decoration: none;
    font-size: 14px;
    transition: all 0.2s;
}

.footer-links a:hover {
    color: var(--white);      /* 悬停变白 */
    text-decoration: underline;
}

/* 版权文字 */
.copyright {
    color: #7f8c8d; /* 深一点的灰色 */
    font-size: 13px;
    margin: 0;
}

/* =========================================
   7. 移动端适配 (Responsive)
   ========================================= */
@media (max-width: 600px) {
    nav {
        flex-direction: column;
        gap: 15px;
    }

    .menu {
        flex-direction: column;
        width: 100%;
        gap: 10px;
    }

    .lang-select-wrapper {
        margin-left: 0; /* 手机上取消左边距，居中显示 */
    }

    .hero h1 {
        font-size: 1.8rem;
    }

    .upload-area {
        padding: 2rem 1rem;
    }

    .footer-links {
        gap: 15px; /* 手机上链接间距缩小 */
    }
}