/* ==========================================
   华兴玖零 — 极简清爽风 · 思源宋体
   Clean Minimal Theme + Noto Serif SC
   ========================================== */

@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@300;400;500;600;700;900&display=swap');

/* ===== CSS 变量 ===== */
:root {
    /* 品牌色 — 克制优雅的红 */
    --primary: #c0392b;
    --primary-light: #e74c3c;
    --primary-bg: #fdf2f2;

    /* 浅色背景层 */
    --bg-page: #fafaf9;
    --bg-card: #ffffff;
    --bg-card-hover: #f8f8f7;
    --bg-muted: #f3f3f1;

    /* 文字 */
    --text-primary: #1a1a1a;
    --text-secondary: #5c5c5c;
    --text-muted: #999999;

    /* 边框 */
    --border: #e8e8e4;
    --border-light: #f0f0ec;

    /* 功能色 */
    --success: #27ae60;
    --error: #c0392b;

    /* 圆角 — 柔和 */
    --radius: 12px;
    --radius-sm: 8px;
    --radius-xs: 6px;

    /* 阴影 — 轻盈 */
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.04);
    --shadow: 0 2px 12px rgba(0,0,0,0.06);
    --shadow-lg: 0 8px 40px rgba(0,0,0,0.08);

    /* 字体 */
    --font-serif: 'Noto Serif SC', 'Source Han Serif SC', 'STSong', 'SimSun', serif;
    --font-mono: 'Consolas', 'SF Mono', 'Courier New', monospace;

    /* 间距 */
    --section-gap: 100px;
}

/* ===== 全局重置 ===== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-serif);
    background: var(--bg-page);
    color: var(--text-primary);
    line-height: 1.8;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* 滚动条 — 纤细 */
::-webkit-scrollbar { width: 4px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
    background: #ddd;
    border-radius: 2px;
}
::-webkit-scrollbar-thumb:hover { background: #bbb; }

/* ===== 选择颜色 ===== */
::selection {
    background: var(--primary);
    color: #fff;
}

/* ===== 链接 ===== */
a {
    color: var(--primary);
    text-decoration: none;
    transition: color 0.2s;
}
a:hover { color: var(--primary-light); }

/* ===== 导航栏 ===== */
.navbar {
    position: fixed;
    top: 0; left: 0; right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    padding: 0 48px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: all 0.3s;
}

.navbar .logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-family: var(--font-serif);
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: 0.02em;
}

.navbar .logo img {
    height: 32px;
    width: auto;
}

.nav-links {
    display: flex;
    gap: 40px;
    list-style: none;
    align-items: center;
}

.nav-links a {
    color: var(--text-secondary);
    font-size: 0.88rem;
    font-weight: 500;
    font-family: var(--font-serif);
    transition: all 0.2s;
    padding: 4px 0;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--primary);
}

.nav-links a.active {
    border-bottom: 2px solid var(--primary);
    padding-bottom: 2px;
}

/* ===== 按钮 ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    border-radius: var(--radius-xs);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    border: none;
    transition: all 0.25s;
    text-decoration: none;
    font-family: var(--font-serif);
    letter-spacing: 0.02em;
}

.btn-primary {
    background: var(--primary);
    color: #fff;
}
.btn-primary:hover {
    background: var(--primary-light);
    color: #fff;
    transform: translateY(-1px);
    box-shadow: 0 4px 16px rgba(192, 57, 43, 0.2);
}

.btn-outline {
    background: transparent;
    color: var(--text-primary);
    border: 1px solid var(--border);
}
.btn-outline:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: var(--primary-bg);
}

.btn-accent {
    background: var(--text-primary);
    color: #fff;
}
.btn-accent:hover {
    opacity: 0.85;
    transform: translateY(-1px);
}

/* ===== Hero 区域 ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    padding: 100px 48px 60px;
    background: var(--bg-page);
}

.hero-content {
    max-width: 1200px;
    width: 100%;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 80px;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-text h1 {
    font-family: var(--font-serif);
    font-size: 3.2rem;
    font-weight: 900;
    line-height: 1.2;
    margin-bottom: 20px;
    color: var(--text-primary);
    letter-spacing: 0.03em;
}

.hero-text h1 span {
    color: var(--primary);
}

.hero-text .subtitle {
    font-family: var(--font-serif);
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 36px;
    max-width: 480px;
    font-weight: 400;
    line-height: 1.8;
}

.hero-text .badge {
    display: inline-block;
    padding: 6px 18px;
    background: var(--primary-bg);
    border: 1px solid rgba(192, 57, 43, 0.15);
    border-radius: 20px;
    font-size: 0.8rem;
    color: var(--primary);
    margin-bottom: 28px;
    font-weight: 500;
    letter-spacing: 0.04em;
    font-family: var(--font-serif);
}

.hero-buttons {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

.hero-visual {
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

.hero-visual .drone-svg {
    width: 100%;
    max-width: 440px;
}

/* ===== 统计数据区 ===== */
.stats-section {
    padding: 48px 48px;
    background: #fff;
    border-top: 1px solid var(--border-light);
    border-bottom: 1px solid var(--border-light);
}

.stats-container {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 32px;
}

.stat-item {
    text-align: center;
    padding: 24px 16px;
}

.stat-item .stat-number {
    font-size: 2.8rem;
    font-weight: 900;
    font-family: var(--font-serif);
    color: var(--primary);
    line-height: 1;
}

.stat-item .stat-label {
    font-size: 0.84rem;
    color: var(--text-muted);
    margin-top: 8px;
    font-family: var(--font-serif);
    letter-spacing: 0.03em;
}

/* ===== 通用区块 ===== */
.section {
    padding: var(--section-gap) 48px;
    max-width: 1200px;
    margin: 0 auto;
}

.section-title {
    text-align: center;
    margin-bottom: 56px;
}

.section-title h2 {
    font-family: var(--font-serif);
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--text-primary);
    letter-spacing: 0.02em;
}

.section-title p {
    color: var(--text-secondary);
    font-size: 1rem;
    font-family: var(--font-serif);
    font-weight: 400;
}

/* ===== 产品特色卡片 ===== */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.feature-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 36px 32px;
    transition: all 0.3s;
}

.feature-card:hover {
    border-color: #ddd;
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.feature-card .feature-icon {
    width: 48px;
    height: 48px;
    background: var(--primary-bg);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--primary);
    font-family: var(--font-serif);
}

.feature-card h3 {
    font-family: var(--font-serif);
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--text-primary);
    letter-spacing: 0.02em;
}

.feature-card p {
    color: var(--text-secondary);
    font-size: 0.88rem;
    font-weight: 400;
    line-height: 1.8;
}

/* ===== 教学资源视频卡片 ===== */
.tutorials-grid {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.tutorial-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    transition: all 0.3s;
    cursor: pointer;
    display: block;
    text-decoration: none;
    color: inherit;
}

.tutorial-card:hover {
    border-color: #ddd;
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.tutorial-thumb {
    position: relative;
    width: 100%;
    height: 190px;
    background: var(--bg-muted);
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}

.tutorial-thumb img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.tutorial-play-icon {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0,0,0,0.25);
    opacity: 0;
    transition: opacity 0.3s;
}

.tutorial-card:hover .tutorial-play-icon { opacity: 1; }

.tutorial-play-icon svg {
    filter: drop-shadow(0 2px 8px rgba(0,0,0,0.3));
}

.tutorial-info {
    padding: 22px 20px;
}

.tutorial-info h3 {
    font-family: var(--font-serif);
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.tutorial-info p {
    font-size: 0.82rem;
    color: var(--text-secondary);
    margin-bottom: 12px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    font-weight: 400;
}

.tutorial-tag {
    display: inline-block;
    padding: 4px 12px;
    background: var(--primary-bg);
    border-radius: 12px;
    font-size: 0.72rem;
    color: var(--primary);
    font-weight: 500;
    font-family: var(--font-serif);
    letter-spacing: 0.03em;
}

/* ===== 页脚 ===== */
.footer {
    background: #fff;
    color: var(--text-primary);
    padding: 60px 48px 32px;
    border-top: 1px solid var(--border-light);
}

.footer-container { max-width: 1200px; margin: 0 auto; }

.footer-top {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 48px;
    margin-bottom: 40px;
}

.footer-brand .logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--text-primary);
    font-family: var(--font-serif);
}

.footer-brand .logo img {
    height: 30px;
    width: auto;
}

.footer-brand p {
    color: var(--text-muted);
    font-size: 0.86rem;
    max-width: 320px;
    font-weight: 400;
}

.footer-col h4 {
    font-family: var(--font-serif);
    font-size: 0.9rem;
    margin-bottom: 20px;
    color: var(--text-primary);
    letter-spacing: 0.03em;
    font-weight: 600;
}

.footer-col a {
    display: block;
    color: var(--text-muted);
    font-size: 0.84rem;
    margin-bottom: 12px;
    transition: all 0.2s;
    font-weight: 400;
}
.footer-col a:hover { color: var(--primary); }

.footer-bottom {
    padding-top: 28px;
    border-top: 1px solid var(--border-light);
    text-align: center;
    color: var(--text-muted);
    font-size: 0.8rem;
    font-weight: 400;
}

/* ===== 下载中心 ===== */
.search-bar {
    max-width: 800px;
    width: 100%;
    margin: 0 auto 32px;
    display: flex;
    gap: 12px;
    align-items: center;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 8px 8px 8px 24px;
    transition: all 0.25s;
}

.search-bar:focus-within {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(192, 57, 43, 0.06);
}

.search-bar input {
    flex: 1;
    background: transparent;
    border: none;
    outline: none;
    color: var(--text-primary);
    font-size: 1rem;
    padding: 10px 0;
    min-width: 0;
    font-family: var(--font-serif);
}

.search-bar input::placeholder { color: var(--text-muted); }

.filter-section {
    max-width: 1200px;
    margin: 0 auto 32px;
    display: flex;
    align-items: flex-start;
    gap: 16px;
    flex-wrap: wrap;
}

.filter-label {
    color: var(--text-secondary);
    font-size: 0.88rem;
    font-weight: 500;
    padding: 6px 0;
    white-space: nowrap;
    flex-shrink: 0;
    font-family: var(--font-serif);
}

.filter-chips {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    flex: 1;
}

.category-chip {
    padding: 6px 18px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 20px;
    color: var(--text-secondary);
    font-size: 0.84rem;
    cursor: pointer;
    transition: all 0.25s;
    font-family: var(--font-serif);
}

.category-chip:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: var(--primary-bg);
}

.category-chip.active {
    background: var(--primary);
    border-color: var(--primary);
    color: #fff;
    font-weight: 600;
}

/* 文件列表 */
.file-list {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
}

.file-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    display: flex;
    align-items: flex-start;
    gap: 20px;
    transition: all 0.25s;
}

.file-card:hover {
    border-color: #ddd;
    box-shadow: var(--shadow);
    transform: translateY(-1px);
}

.file-icon-box {
    width: 52px; height: 52px; min-width: 52px;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.85rem;
    font-weight: 700;
    color: #fff;
    font-family: var(--font-mono);
}

.file-info { flex: 1; min-width: 0; }

.file-info .file-name {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 6px;
    word-break: break-word;
    color: var(--text-primary);
    font-family: var(--font-serif);
}

.file-info .file-desc {
    color: var(--text-secondary);
    font-size: 0.82rem;
    margin-bottom: 10px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    font-weight: 400;
}

.file-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
    font-size: 0.76rem;
    color: var(--text-muted);
    margin-bottom: 14px;
    font-family: var(--font-serif);
}

.file-meta span {
    display: flex;
    align-items: center;
    gap: 4px;
}

.file-tags {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
    margin-bottom: 14px;
}

.file-tag {
    padding: 3px 10px;
    background: var(--primary-bg);
    border-radius: 10px;
    font-size: 0.72rem;
    color: var(--primary);
    font-family: var(--font-serif);
}

.file-download-btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 7px 18px;
    background: var(--primary);
    color: #fff;
    font-size: 0.82rem;
    font-weight: 500;
    border-radius: var(--radius-xs);
    transition: all 0.25s;
    cursor: pointer;
    border: none;
    font-family: var(--font-serif);
}

.file-download-btn:hover {
    background: var(--primary-light);
    transform: translateY(-1px);
    box-shadow: 0 2px 10px rgba(192, 57, 43, 0.2);
}

/* 空状态 */
.empty-state {
    text-align: center;
    padding: 80px 20px;
    color: var(--text-secondary);
}

.empty-state .empty-icon {
    font-size: 3rem;
    margin-bottom: 16px;
    opacity: 0.12;
    font-weight: 900;
    color: var(--text-muted);
}

/* ===== 管理后台 ===== */
.admin-wrapper {
    padding: 100px 48px 60px;
    min-height: 100vh;
}

.admin-container { max-width: 960px; margin: 0 auto; }

.admin-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 40px;
    flex-wrap: wrap;
    gap: 16px;
}

.admin-header h1 {
    font-family: var(--font-serif);
    font-size: 1.8rem;
    color: var(--text-primary);
    font-weight: 700;
    letter-spacing: 0.02em;
}

.admin-stats { display: flex; gap: 16px; }

.admin-stat {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 16px 24px;
    text-align: center;
}

.admin-stat .num {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--primary);
    font-family: var(--font-serif);
}

.admin-stat .label {
    font-size: 0.76rem;
    color: var(--text-muted);
    font-family: var(--font-serif);
}

/* 上传卡片 */
.upload-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    margin-bottom: 36px;
}

.upload-card h2 {
    font-family: var(--font-serif);
    font-size: 1.15rem;
    margin-bottom: 24px;
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--text-primary);
    font-weight: 600;
}

.upload-area {
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    padding: 40px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s;
    margin-bottom: 24px;
    position: relative;
    background: var(--bg-muted);
}

.upload-area:hover,
.upload-area.dragover {
    border-color: var(--primary);
    background: var(--primary-bg);
}

.upload-area .upload-icon {
    font-size: 2.5rem;
    color: var(--primary);
    margin-bottom: 12px;
    font-weight: 300;
}

.upload-area p {
    color: var(--text-secondary);
    font-size: 0.88rem;
    font-family: var(--font-serif);
}

.upload-area .selected-file {
    color: var(--primary);
    font-weight: 600;
    margin-top: 8px;
}

.upload-area input[type="file"] {
    position: absolute; inset: 0; opacity: 0; cursor: pointer;
}

.form-group { margin-bottom: 20px; }

.form-group label {
    display: block;
    font-size: 0.86rem;
    color: var(--text-secondary);
    margin-bottom: 8px;
    font-family: var(--font-serif);
    font-weight: 500;
    letter-spacing: 0.02em;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    background: var(--bg-page);
    border: 1px solid var(--border);
    border-radius: var(--radius-xs);
    padding: 12px 16px;
    color: var(--text-primary);
    font-size: 0.9rem;
    outline: none;
    transition: all 0.25s;
    font-family: var(--font-serif);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(192, 57, 43, 0.06);
}

.form-group textarea { resize: vertical; min-height: 80px; }

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

/* 管理文件列表 */
.admin-file-list {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
}

.admin-file-list-header {
    padding: 20px 24px;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.admin-file-list-header h2 {
    font-family: var(--font-serif);
    font-size: 1.05rem;
    color: var(--text-primary);
    font-weight: 600;
}

.admin-file-item {
    padding: 16px 24px;
    border-bottom: 1px solid var(--border-light);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    transition: all 0.2s;
}

.admin-file-item:hover { background: var(--bg-card-hover); }
.admin-file-item:last-child { border-bottom: none; }

.admin-file-info { flex: 1; min-width: 0; }

.admin-file-info .af-name {
    font-weight: 600;
    margin-bottom: 4px;
    word-break: break-word;
    color: var(--text-primary);
    font-family: var(--font-serif);
}

.admin-file-info .af-meta {
    font-size: 0.76rem;
    color: var(--text-muted);
    display: flex;
    gap: 14px;
    flex-wrap: wrap;
    font-family: var(--font-serif);
}

.btn-delete {
    padding: 7px 16px;
    background: var(--primary-bg);
    border: 1px solid rgba(192, 57, 43, 0.15);
    border-radius: var(--radius-xs);
    color: var(--primary);
    font-size: 0.82rem;
    cursor: pointer;
    transition: all 0.25s;
    white-space: nowrap;
    font-family: var(--font-serif);
}

.btn-delete:hover {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}

/* Toast */
.toast {
    position: fixed;
    top: 84px; right: 30px;
    z-index: 9999;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 14px 24px;
    display: flex;
    align-items: center;
    gap: 10px;
    box-shadow: var(--shadow-lg);
    transform: translateX(420px);
    transition: transform 0.3s;
    font-family: var(--font-serif);
}

.toast.show { transform: translateX(0); }
.toast.success { border-left: 3px solid var(--success); }
.toast.error { border-left: 3px solid var(--error); }

/* 加载动画 */
.loading {
    text-align: center;
    padding: 40px;
}

.spinner {
    width: 36px; height: 36px;
    border: 2px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
    margin: 0 auto 12px;
}

@keyframes spin { to { transform: rotate(360deg); } }

/* ===== 登录页 ===== */
.login-page {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-page);
}

.login-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 48px 40px;
    width: 400px;
    max-width: 90vw;
    box-shadow: var(--shadow-lg);
}

.login-logo {
    text-align: center;
    margin-bottom: 32px;
}

.login-logo img {
    height: 44px;
    width: auto;
}

.login-card h2 {
    text-align: center;
    font-family: var(--font-serif);
    font-size: 1.3rem;
    color: var(--text-primary);
    margin-bottom: 6px;
    font-weight: 700;
}

.login-card .hint {
    text-align: center;
    font-size: 0.82rem;
    color: var(--text-muted);
    margin-bottom: 30px;
    font-family: var(--font-serif);
}

.login-card label {
    display: block;
    font-size: 0.86rem;
    color: var(--text-secondary);
    margin-bottom: 8px;
    font-weight: 500;
    font-family: var(--font-serif);
}

.login-card input {
    width: 100%;
    padding: 12px 16px;
    background: var(--bg-page);
    border: 1px solid var(--border);
    border-radius: var(--radius-xs);
    color: var(--text-primary);
    font-size: 1rem;
    transition: all 0.25s;
    font-family: var(--font-serif);
}

.login-card input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(192, 57, 43, 0.06);
}

.login-card .btn-login {
    width: 100%;
    padding: 13px;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: var(--radius-xs);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.25s;
    font-family: var(--font-serif);
    letter-spacing: 0.06em;
    margin-top: 8px;
}

.login-card .btn-login:hover {
    background: var(--primary-light);
    box-shadow: 0 4px 16px rgba(192, 57, 43, 0.2);
}

.login-card .btn-login:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.login-error {
    background: var(--primary-bg);
    border: 1px solid rgba(192, 57, 43, 0.15);
    border-radius: var(--radius-xs);
    color: var(--primary);
    padding: 10px 14px;
    font-size: 0.82rem;
    text-align: center;
    margin-bottom: 16px;
    display: none;
    font-family: var(--font-serif);
}

.login-error.show { display: block; animation: shake 0.4s; }

.login-back {
    text-align: center;
    margin-top: 20px;
}

.login-back a {
    color: var(--text-muted);
    font-size: 0.82rem;
    font-family: var(--font-serif);
}
.login-back a:hover { color: var(--primary); }

@keyframes shake {
    0%,100% { transform: translateX(0); }
    25% { transform: translateX(-6px); }
    75% { transform: translateX(6px); }
}

/* ===== 移动端汉堡菜单 ===== */
.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 8px;
    z-index: 1001;
}

.nav-toggle span {
    width: 24px; height: 2px;
    background: var(--text-primary);
    transition: all 0.3s;
}

.nav-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}
.nav-toggle.active span:nth-child(2) { opacity: 0; }
.nav-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

.nav-menu-overlay {
    display: none;
    position: fixed;
    top: 64px; left: 0; right: 0; bottom: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    z-index: 999;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    padding-top: 40px;
    gap: 16px;
}

.nav-menu-overlay.open { display: flex; }

.nav-menu-overlay a {
    font-size: 1.2rem;
    color: var(--text-secondary);
    font-weight: 500;
    padding: 14px 32px;
    transition: all 0.2s;
    font-family: var(--font-serif);
    letter-spacing: 0.04em;
    border-radius: var(--radius-sm);
}

.nav-menu-overlay a:hover,
.nav-menu-overlay a.active {
    color: var(--primary);
    background: var(--primary-bg);
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
    .navbar { padding: 0 24px; }
    .nav-links { display: none; }
    .nav-toggle { display: flex; }

    .hero { padding: 90px 24px 40px; }
    .hero-content {
        grid-template-columns: 1fr;
        gap: 40px;
        text-align: center;
    }
    .hero-text h1 { font-size: 2rem; }
    .hero-text .subtitle { font-size: 0.92rem; }
    .hero-buttons { justify-content: center; }
    .hero-visual .drone-svg { max-width: 280px; }

    .stats-container { grid-template-columns: repeat(3, 1fr); gap: 16px; }
    .stat-item { padding: 16px 8px; }
    .stat-item .stat-number { font-size: 1.8rem; }
    .stat-item .stat-label { font-size: 0.74rem; }

    .features-grid { grid-template-columns: 1fr; }
    .tutorials-grid { grid-template-columns: 1fr; }
    .file-list { grid-template-columns: 1fr; }
    .file-card { padding: 18px; gap: 14px; }
    .file-icon-box { width: 44px; height: 44px; min-width: 44px; font-size: 0.78rem; }
    .file-info .file-name { font-size: 0.9rem; }
    .file-meta { gap: 10px; font-size: 0.72rem; }

    .footer-top { grid-template-columns: 1fr; gap: 32px; }
    .footer { padding: 48px 24px 24px; }

    .form-row { grid-template-columns: 1fr; }
    .admin-stats { flex-direction: row; flex-wrap: wrap; gap: 10px; }
    .admin-stat { padding: 12px 14px; flex: 1; min-width: 90px; }
    .admin-stat .num { font-size: 1.1rem; }
    .admin-header { flex-direction: column; align-items: flex-start; }
    .admin-header h1 { font-size: 1.4rem; }

    .section { padding: 60px 24px; }
    .section-title h2 { font-size: 1.6rem; }
    .admin-wrapper { padding: 90px 20px 40px; }

    .search-bar { padding: 8px 8px 8px 18px; gap: 8px; }
    .search-bar input { font-size: 0.9rem; padding: 8px 0; }
    .filter-section { gap: 10px; }
    .filter-label { font-size: 0.82rem; }
    .category-chip { padding: 5px 14px; font-size: 0.8rem; }

    .upload-card { padding: 20px 16px; }
    .upload-area { padding: 24px 16px; }
    .admin-file-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
        padding: 14px 16px;
    }
    .admin-file-info .af-meta { gap: 10px; font-size: 0.72rem; }
    .btn-delete { align-self: flex-end; }
    .toast { right: 16px; left: 16px; top: 80px; }
}

@media (max-width: 480px) {
    .stats-container { grid-template-columns: repeat(3, 1fr); gap: 8px; }
    .stat-item { padding: 12px 4px; }
    .stat-item .stat-number { font-size: 1.5rem; }
    .hero-text h1 { font-size: 1.7rem; }
    .hero-buttons { flex-direction: column; width: 100%; }
    .hero-buttons .btn { width: 100%; justify-content: center; }
    .file-card { flex-direction: column; align-items: flex-start; }
}