body {
    font-family: Arial, sans-serif;
    margin: 0;
    background: #f5f7fb;
}

nav {
    background: #1f2937;
    padding: 14px 20px;
}

nav a {
    color: white;
    margin-right: 14px;
    text-decoration: none;
}

main, .container {
    max-width: 1100px;
    margin: 30px auto;
    background: white;
    padding: 24px;
    border-radius: 10px;
}

input, button {
    display: block;
    margin: 10px 0;
    padding: 10px;
    width: 100%;
    max-width: 420px;
}

button {
    background: #2563eb;
    color: white;
    border: none;
    cursor: pointer;
}

.grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    margin-bottom: 24px;
}

.card {
    background: #eef2ff;
    padding: 16px;
    border-radius: 8px;
}

table {
    width: 100%;
    border-collapse: collapse;
}

th, td {
    border: 1px solid #ddd;
    padding: 10px;
}

th {
    background: #f3f4f6;
}