/* ==================== CSS变量与基础 ==================== */
:root {
    --white: #ffffff;
    --black: #000000;
    --gray-50: #fafafa;
    --gray-100: #f5f5f5;
    --gray-200: #e5e5e5;
    --gray-300: #d4d4d4;
    --gray-400: #a3a3a3;
    --gray-500: #737373;
    --gray-600: #525252;
    --gray-700: #404040;
    --gray-800: #262626;
    --gray-900: #171717;
    --font-mono: 'SF Mono', 'Fira Code', 'Courier New', monospace;
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 20px 50px rgba(0, 0, 0, 0.2);
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background: var(--white);
    color: var(--black);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a {
    color: var(--black);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    text-decoration: underline;
    text-underline-offset: 3px;
}

img {
    max-width: 100%;
    height: auto;
}

/* ==================== 导航栏 ==================== */
.navbar {
    background: var(--black);
    color: var(--white);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-md);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 60px;
}

.nav-brand {
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--white);
    display: flex;
    align-items: center;
    gap: 8px;
    letter-spacing: -0.5px;
}

.nav-brand:hover {
    text-decoration: none;
    opacity: 0.85;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 4px;
}

.nav-menu a {
    color: var(--gray-300);
    padding: 8px 14px;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 6px;
    transition: var(--transition);
}

.nav-menu a:hover {
    color: var(--white);
    background: var(--gray-800);
    text-decoration: none;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    width: 26px;
    height: 2px;
    background: var(--white);
    border-radius: 2px;
    transition: var(--transition);
}

/* ==================== 主内容 ==================== */
.main-content {
    flex: 1;
    padding: 30px 0;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ==================== Hero ==================== */
.hero-section {
    background: var(--black);
    color: var(--white);
    text-align: center;
    padding: 60px 20px;
    margin-bottom: 30px;
}

.hero-section h1 {
    font-size: 2.5rem;
    font-weight: 800;
    letter-spacing: -1px;
    margin-bottom: 8px;
}

.hero-section p {
    font-size: 1.15rem;
    color: var(--gray-400);
}

/* ==================== 任务卡片网格 ==================== */
.task-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
    margin: 20px 0 30px;
}

.task-card {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-md);
    padding: 22px;
    transition: var(--transition);
}

.task-card:hover {
    border-color: var(--black);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.task-card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
}

.task-reward {
    background: var(--black);
    color: var(--white);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.task-title {
    font-size: 1.15rem;
    font-weight: 600;
    margin-bottom: 8px;
}

.task-desc {
    color: var(--gray-500);
    font-size: 0.9rem;
    margin-bottom: 12px;
    line-height: 1.5;
}

.task-meta {
    display: flex;
    gap: 16px;
    font-size: 0.85rem;
    color: var(--gray-500);
    margin-bottom: 15px;
}

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

/* ==================== 按钮 ==================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    padding: 10px 20px;
    border: 2px solid var(--black);
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    background: var(--white);
    color: var(--black);
}

.btn:hover {
    text-decoration: none;
}

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

.btn-primary:hover {
    background: var(--gray-800);
}

.btn-outline {
    background: var(--white);
    color: var(--black);
}

.btn-outline:hover {
    background: var(--gray-100);
}

.btn-error {
    background: var(--white);
    color: var(--black);
    border-color: var(--gray-400);
}

.btn-error:hover {
    background: var(--gray-900);
    color: var(--white);
}

.btn-success {
    background: var(--black);
    color: var(--white);
}

.btn-success:hover {
    background: var(--gray-800);
}

.btn-lg {
    padding: 14px 32px;
    font-size: 1.1rem;
}

.btn-sm {
    padding: 6px 12px;
    font-size: 0.85rem;
}

.btn-block {
    display: flex;
    width: 100%;
}

/* ==================== 表单 ==================== */
.form-group {
    margin-bottom: 18px;
}

.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 6px;
    font-size: 0.9rem;
}

.form-control {
    width: 100%;
    padding: 10px 14px;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    font-family: var(--font-sans);
    transition: var(--transition);
    background: var(--white);
    color: var(--black);
}

.form-control:focus {
    outline: none;
    border-color: var(--black);
}

textarea.form-control {
    resize: vertical;
    min-height: 100px;
}

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

.form-inline {
    width: auto;
    display: inline-block;
    padding: 4px 8px;
    font-size: 0.85rem;
}

/* ==================== 验证/认证页面 ==================== */
.auth-container {
    max-width: 460px;
    margin: 40px auto;
}

.auth-box {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: 35px;
}

.auth-box h2 {
    font-size: 1.35rem;
    margin-bottom: 25px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.auth-link {
    text-align: center;
    margin-top: 18px;
    color: var(--gray-500);
    font-size: 0.9rem;
}

/* ==================== 提醒 ==================== */
.alert {
    padding: 12px 18px;
    border-radius: var(--radius-sm);
    margin-bottom: 18px;
    font-size: 0.9rem;
}

.alert-error {
    background: var(--gray-100);
    border: 1px solid var(--gray-400);
    color: var(--black);
}

.alert-success {
    background: var(--gray-100);
    border: 1px solid var(--black);
    color: var(--black);
}

.alert-info {
    background: var(--gray-100);
    border: 1px solid var(--gray-300);
    color: var(--black);
}

/* ==================== 用户中心 ==================== */
.dashboard {
    margin-top: 20px;
}

.user-info-card {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: 30px;
    margin-bottom: 25px;
}

.balance-display {
    margin: 18px 0;
}

.balance-label {
    display: block;
    font-size: 0.85rem;
    color: var(--gray-500);
    margin-bottom: 4px;
}

.balance-amount {
    font-size: 2.5rem;
    font-weight: 800;
    letter-spacing: -1px;
}

.user-actions {
    display: flex;
    gap: 10px;
    margin-top: 15px;
}

/* ==================== 选项卡 ==================== */
.tabs {
    display: flex;
    gap: 0;
    border-bottom: 2px solid var(--gray-200);
    margin-bottom: 20px;
}

.tab-btn {
    padding: 10px 20px;
    border: none;
    background: none;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--gray-500);
    transition: var(--transition);
    border-bottom: 2px solid transparent;
    margin-bottom: -2px;
}

.tab-btn.active {
    color: var(--black);
    border-bottom-color: var(--black);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

/* ==================== 表格 ==================== */
.table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
}

.table th {
    background: var(--gray-100);
    padding: 12px 14px;
    text-align: left;
    font-weight: 600;
    border-bottom: 2px solid var(--gray-300);
}

.table td {
    padding: 10px 14px;
    border-bottom: 1px solid var(--gray-200);
}

.table tr:hover td {
    background: var(--gray-50);
}

/* ==================== 任务详情 ==================== */
.task-detail {
    margin-top: 20px;
}

.task-detail-card {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: 35px;
}

.task-detail-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 15px;
    flex-wrap: wrap;
    gap: 15px;
}

.task-detail-header h1 {
    font-size: 1.6rem;
    font-weight: 700;
}

.task-reward-badge {
    background: var(--black);
    color: var(--white);
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    font-weight: 700;
    font-size: 1rem;
    white-space: nowrap;
}

.task-detail-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    padding: 15px 0;
    border-bottom: 1px solid var(--gray-200);
    margin-bottom: 20px;
    color: var(--gray-500);
    font-size: 0.9rem;
}

.task-detail-meta span {
    display: flex;
    align-items: center;
    gap: 5px;
}

.task-detail-body {
    line-height: 1.8;
    margin-bottom: 25px;
}

.task-actions {
    padding-top: 20px;
    border-top: 1px solid var(--gray-200);
}

/* ==================== 提交记录卡片 ==================== */
.submissions-section {
    margin-top: 30px;
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: 25px;
}

.submissions-section h3 {
    font-size: 1.15rem;
    margin-bottom: 15px;
}

.submission-card {
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-sm);
    padding: 15px;
    margin-bottom: 10px;
}

.submission-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 8px;
}

.submission-status {
    font-weight: 600;
    font-size: 0.85rem;
    padding: 4px 10px;
    border-radius: 20px;
}

.status-accepted { background: var(--gray-200); color: var(--black); }
.status-submitted { background: var(--gray-300); color: var(--black); }
.status-approved { background: var(--black); color: var(--white); }
.status-rejected { background: var(--gray-100); border: 1px solid var(--gray-400); }

.submission-actions {
    margin-top: 10px;
    display: flex;
    gap: 8px;
}

/* ==================== 分页 ==================== */
.pagination {
    display: flex;
    justify-content: center;
    gap: 8px;
    margin-top: 30px;
}

.page-link {
    padding: 8px 14px;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    transition: var(--transition);
}

.page-link:hover {
    background: var(--gray-100);
    text-decoration: none;
}

.page-link.active {
    background: var(--black);
    color: var(--white);
    border-color: var(--black);
}

/* ==================== 空状态 ==================== */
.empty-state {
    text-align: center;
    padding: 50px 20px;
    color: var(--gray-400);
}

.empty-state i {
    font-size: 2.5rem;
    margin-bottom: 10px;
}

/* ==================== 页脚 ==================== */
.footer {
    background: var(--gray-100);
    border-top: 1px solid var(--gray-200);
    padding: 25px 0;
    margin-top: auto;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    text-align: center;
    color: var(--gray-500);
    font-size: 0.9rem;
}

.footer-container p {
    margin: 4px 0;
}

/* ==================== 充值 ==================== */
.recharge-info {
    text-align: center;
    margin: 10px 0;
    font-size: 1.1rem;
}

.recharge-rate {
    text-align: center;
    color: var(--gray-500);
    margin-bottom: 15px;
}

.quick-amounts {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
    margin-bottom: 18px;
}

.amount-btn {
    padding: 10px;
    border: 2px solid var(--gray-200);
    background: var(--white);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition);
}

.amount-btn:hover {
    border-color: var(--black);
    background: var(--gray-100);
}

.amount-btn.active {
    background: var(--black);
    color: var(--white);
    border-color: var(--black);
}

/* ==================== 通用辅助 ==================== */
.info-text {
    color: var(--gray-500);
    font-size: 0.9rem;
    margin: 10px 0;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.section-header h2 {
    font-size: 1.25rem;
}

.task-count {
    color: var(--gray-500);
    font-size: 0.9rem;
}

/* ==================== 管理员面板 ==================== */
.admin-navbar {
    background: var(--gray-900);
}

.admin-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 25px 20px;
}

.admin-dashboard h1 {
    font-size: 1.5rem;
    margin-bottom: 25px;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 16px;
}

.stat-card {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-md);
    padding: 22px;
    display: flex;
    align-items: center;
    gap: 16px;
    transition: var(--transition);
}

.stat-card:hover {
    border-color: var(--black);
    box-shadow: var(--shadow-sm);
}

.stat-card i {
    font-size: 2rem;
}

.stat-value {
    display: block;
    font-size: 1.6rem;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--gray-500);
}

.admin-section {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: 25px;
    margin: 0 auto 25px;
    max-width: 1200px;
}

.admin-section h2 {
    font-size: 1.2rem;
    margin-bottom: 18px;
}

.admin-table {
    overflow-x: auto;
}

/* ==================== 管理员登录 ==================== */
.admin-login-container {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background: var(--white);
}

.admin-login-box {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: 35px;
    width: 100%;
    max-width: 400px;
}

.admin-login-box h2 {
    font-size: 1.25rem;
    margin-bottom: 25px;
}

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

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.92);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.fade-in {
    animation: fadeInUp 0.5s ease forwards;
}

.slide-in {
    animation: slideInRight 0.4s ease forwards;
}

.scale-in {
    animation: scaleIn 0.35s ease forwards;
}

/* ==================== 响应式 ==================== */
@media (max-width: 768px) {
    .nav-toggle {
        display: flex;
    }
    
    .nav-menu {
        display: none;
        position: absolute;
        top: 60px;
        left: 0;
        right: 0;
        background: var(--black);
        flex-direction: column;
        padding: 10px 20px;
        box-shadow: var(--shadow-lg);
    }
    
    .nav-menu.active {
        display: flex;
    }
    
    .nav-menu a {
        padding: 12px 0;
        border-bottom: 1px solid var(--gray-800);
    }
    
    .hero-section h1 {
        font-size: 1.8rem;
    }
    
    .hero-section {
        padding: 40px 20px;
    }
    
    .task-grid {
        grid-template-columns: 1fr;
    }
    
    .task-detail-header {
        flex-direction: column;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: 1fr 1fr;
    }
    
    .quick-amounts {
        grid-template-columns: 1fr 1fr;
    }
    
    .user-actions {
        flex-direction: column;
    }
    
    .table {
        font-size: 0.8rem;
    }
    
    .table th, .table td {
        padding: 8px 6px;
    }
}

@media (max-width: 480px) {
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .auth-box {
        padding: 20px;
    }
    
    .task-detail-card {
        padding: 20px;
    }
}