:root {
    --primary: #3498db;
    --secondary: #2c3e50;
    --bg: #f4f6f9;
    --white: #ffffff;
    --text: #333;
}

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

body {
    background-color: var(--bg);
    color: var(--text);
    min-height: 100vh;
    display: flex;
}

body.login-page {
    display: flex;
    justify-content: center;
    align-items: center;
    background: var(--primary);
}

.sidebar {
    width: 250px;
    background: var(--secondary);
    color: white;
    padding: 1rem;
    position: fixed;
    height: 100%;
    top: 0;
    left: 0;
}

.main-content {
    margin-left: 250px;
    padding: 2rem;
    width: 100%;
}

.nav-links {
    list-style: none;
    margin-top: 2rem;
}

.nav-links a {
    display: block;
    color: #ecf0f1;
    text-decoration: none;
    padding: 10px;
    margin-bottom: 5px;
    border-radius: 4px;
    transition: 0.2s;
}

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

.card {
    background: var(--white);
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    margin-bottom: 1rem;
}

table {
    width: 100%;
    border-collapse: collapse;
    background: var(--white);
    margin-top: 1rem;
    border-radius: 8px;
    overflow: hidden;
}

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

th {
    background: var(--secondary);
    color: white;
}

input, select, textarea {
    width: 100%;
    padding: 10px;
    margin: 5px 0 15px;
    border: 1px solid #ddd;
    border-radius: 4px;
}

.btn {
    background: var(--secondary);
    color: white;
    padding: 10px 20px;
    border: none;
    cursor: pointer;
    border-radius: 4px;
    transition: 0.3s;
}

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

.login-box {
    background: var(--white);
    padding: 2rem;
    border-radius: 8px;
    width: 350px;
    text-align: center;
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
}

h2 {
    color: var(--secondary);
    margin-bottom: 1rem;
}