body {
    font-family: Arial, sans-serif;
    margin: 0;
    background: #f4f6f8;
}

header {
    background: #1f2937;
    color: white;
    padding: 20px;
    text-align: center;
}

.container {
    padding: 30px;
    max-width: 1000px;
    margin: auto;
}

.card {
    content: center;
    background: white;
    padding: 20px;
    margin-bottom: 20px;
    border-radius: 10px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.08);
}

h1, h2, h3 {
    margin-top: 0;
}

input, button {
    padding: 10px;
    margin: 5px 0;
    width: 20%;
    border-radius: 5px;
    border: 1px solid #ccc;
}

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

button:hover {
    background: #1e40af;
}

.result {
    background: #eef2ff;
    padding: 15px;
    border-radius: 8px;
    margin-top: 15px;
}

.nav {
    text-align: center;
    margin-bottom: 20px;
}

.nav a {
    margin: 0 10px;
    text-decoration: none;
    color: #2563eb;
    font-weight: bold;
}