* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
    overflow: hidden;
}

nav {
    background: linear-gradient(90deg, #4f46e5, #7c3aed);
    color: white;
    padding: 20px 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

nav a {
    color: white;
    text-decoration: none;
    margin-left: 20px;
    padding: 8px 16px;
    border-radius: 6px;
    transition: background 0.3s;
}

nav a:hover {
    background: rgba(255,255,255,0.2);
}

.main-content {
    padding: 40px;
}

.checkin-card {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: white;
    padding: 40px;
    border-radius: 20px;
    margin-bottom: 40px;
    text-align: center;
}

#current-time {
    font-size: 2.5em;
    margin: 20px 0;
    font-weight: bold;
}

.checkin-form {
    max-width: 500px;
    margin: 30px auto 0;
}

textarea {
    width: 100%;
    padding: 15px;
    border: none;
    border-radius: 10px;
    font-size: 16px;
    margin-bottom: 20px;
    resize: vertical;
}

.checkin-btn {
    background: white;
    color: #f5576c;
    border: none;
    padding: 15px 40px;
    font-size: 18px;
    border-radius: 50px;
    cursor: pointer;
    font-weight: bold;
    transition: transform 0.3s;
}

.checkin-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.2);
}

.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 50px;
}

.feature {
    background: white;
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    text-align: center;
    transition: transform 0.3s;
}

.feature:hover {
    transform: translateY(-5px);
}

.auth-container {
    max-width: 400px;
    margin: 100px auto;
    background: white;
    padding: 40px;
    border-radius: 20px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.2);
}

.auth-container input {
    width: 100%;
    padding: 12px 20px;
    margin: 10px 0 20px;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    font-size: 16px;
}

.auth-container button {
    width: 100%;
    padding: 15px;
    background: linear-gradient(90deg, #4f46e5, #7c3aed);
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 16px;
    cursor: pointer;
}

.error {
    color: #dc2626;
    background: #fee2e2;
    padding: 10px;
    border-radius: 8px;
    margin-bottom: 20px;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 20px;
}

th, td {
    padding: 15px;
    text-align: left;
    border-bottom: 1px solid #e5e7eb;
}

th {
    background: #f9fafb;
    font-weight: 600;
}

.stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin: 30px 0;
}

.stat-card {
    background: white;
    padding: 20px;
    border-radius: 15px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    text-align: center;
}

.stat-number {
    font-size: 2.5em;
    font-weight: bold;
    color: #4f46e5;
    margin: 10px 0;
}
.success-message {
    background: #d1fae5;
    color: #065f46;
    padding: 12px 20px;
    border-radius: 8px;
    margin: 20px 0;
    text-align: center;
    border: 1px solid #a7f3d0;
}

.error-message {
    background: #fee2e2;
    color: #dc2626;
    padding: 12px 20px;
    border-radius: 8px;
    margin: 20px 0;
    text-align: center;
    border: 1px solid #fecaca;
}
/* 任务系统样式 */
.tasks-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

.task-category {
    margin-bottom: 25px;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.category-header {
    background: linear-gradient(90deg, #4f46e5, #7c3aed);
    color: white;
    padding: 15px 20px;
    font-size: 1.1em;
    font-weight: bold;
}

.task-list {
    background: white;
}

.task-item {
    padding: 15px 20px;
    border-bottom: 1px solid #e5e7eb;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background 0.3s;
}

.task-item:last-child {
    border-bottom: none;
}

.task-item:hover {
    background: #f9fafb;
}

.task-info h4 {
    margin: 0 0 5px 0;
    color: #333;
}

.task-meta {
    color: #666;
    font-size: 0.9em;
}

.task-actions {
    display: flex;
    gap: 10px;
}

.task-btn {
    padding: 8px 16px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: bold;
    transition: all 0.3s;
}

.task-btn.complete {
    background: #10b981;
    color: white;
}

.task-btn.complete:hover {
    background: #059669;
}

.task-btn.undo {
    background: #f59e0b;
    color: white;
}

.task-btn.undo:hover {
    background: #d97706;
}

.task-completed {
    opacity: 0.7;
}

.task-completed .task-info h4 {
    text-decoration: line-through;
    color: #9ca3af;
}

/* 统计卡片 */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin: 30px 0;
}

.stat-card {
    background: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    text-align: center;
}

.stat-value {
    font-size: 2.5em;
    font-weight: bold;
    color: #4f46e5;
    margin: 10px 0;
}

.stat-label {
    color: #666;
    font-size: 0.9em;
}