:root {
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --danger-color: #e74c3c;
    --dark-color: #2c3e50;
    --light-color: #ecf0f1;
    --gray-color: #95a5a6;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --border-radius: 8px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    background: #f8f9fa;
    color: #333;
    margin: 0;
    padding: 0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

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

a:hover {
    opacity: 0.8;
}

/* Header */
.header {
    background: var(--dark-color);
    color: white;
    padding: 1rem 2rem;
    box-shadow: var(--shadow);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

.header h1 {
    margin: 0;
    font-size: 1.8rem;
}

.nav-link {
    color: white;
    margin-left: 1.5rem;
    padding: 0.5rem 0;
    position: relative;
}

.nav-link:hover {
    color: var(--light-color);
}

.nav-link.active {
    font-weight: bold;
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background: var(--secondary-color);
    border-radius: 3px;
}

/* Main Content */
.container {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 2rem;
    flex: 1;
}

.welcome {
    text-align: center;
    margin-bottom: 3rem;
}

.welcome h1 {
    color: var(--dark-color);
    margin-bottom: 1rem;
}

/* Cards */
.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.card {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    padding: 1.5rem;
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.card h2 {
    color: var(--dark-color);
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

/* Buttons */
.btn {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 0.6rem 1.2rem;
    border-radius: var(--border-radius);
    border: none;
    cursor: pointer;
    font-size: 1rem;
    transition: var(--transition);
    text-align: center;
    margin: 0.5rem 0.5rem 0.5rem 0;
}

.btn:hover {
    opacity: 0.9;
    transform: translateY(-2px);
}

.btn.secondary {
    background: var(--gray-color);
}

.btn.danger {
    background: var(--danger-color);
}

.action-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1rem;
}

/* Forms */
.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--dark-color);
}

.form-group input[type="text"],
.form-group input[type="password"] {
    width: 100%;
    padding: 0.8rem;
    border: 1px solid #ddd;
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(52, 152, 219, 0.2);
}

/* Login Page */
.login-container {
    max-width: 400px;
    margin: 4rem auto;
    padding: 2rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.login-container h1 {
    text-align: center;
    margin-bottom: 1.5rem;
    color: var(--dark-color);
}

.error-message {
    background: #fde8e8;
    color: var(--danger-color);
    padding: 0.8rem;
    border-radius: var(--border-radius);
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
}

/* Footer */
.footer {
    background: var(--dark-color);
    color: white;
    text-align: center;
    padding: 1.5rem;
    margin-top: auto;
}

.footer p {
    margin: 0;
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 768px) {
    .header {
        flex-direction: column;
        text-align: center;
        padding: 1rem;
    }
    
    .header nav {
        margin-top: 1rem;
    }
    
    .nav-link {
        margin: 0 0.5rem;
    }
    
    .container {
        padding: 0 1rem;
    }
    
    .dashboard-grid {
        grid-template-columns: 1fr;
    }
}