:root {
    --primary-color: #3b82f6;
    --bg-color: #f0f2f5;
    --card-bg: #ffffff;
    --text-color: #1e293b;
    --border-color: #e2e8f0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    line-height: 1.6;
}

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

.page {
    width: 100%;
}

#login {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.card {
    background: var(--card-bg);
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    text-align: center;
    width: 100%;
    max-width: 400px;
}

.card h1 {
    margin-top: 0;
}

#login-form input {
    width: 100%;
    padding: 12px;
    margin-bottom: 15px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    box-sizing: border-box;
}

#login-form button {
    width: 100%;
    padding: 12px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1.1rem;
    cursor: pointer;
    transition: background-color 0.2s;
}

#login-form button:hover {
    background-color: #2563eb;
}

.error-message {
    color: #ef4444;
    margin-top: 10px;
    min-height: 1.2em;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--card-bg);
    padding: 10px 20px;
    border-radius: 12px;
    margin-bottom: 20px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

header h2 {
    margin: 0;
}

header nav a, header nav button {
    margin-right: 15px;
    text-decoration: none;
    color: var(--primary-color);
    font-weight: 500;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

main h3 {
    margin-top: 0;
}

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

.stat-card {
    background: var(--card-bg);
    padding: 20px;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.stat-card h4 {
    margin-top: 0;
    color: #64748b;
}

.stat-card p {
    font-size: 2rem;
    font-weight: bold;
    margin-bottom: 0;
    color: var(--primary-color);
}