body {
    font-family: system-ui, sans-serif;
    background: #fff;
    color: #222;
    margin: 0;
    padding: 0;
}
main {
    max-width: 600px;
    margin: 2rem auto;
    padding: 1.5rem;
}
h1 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    text-align: center;
}
table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 2rem;
    font-size: 0.95rem;
}
th, td {
    border: 1px solid #ddd;
    padding: 0.3rem 0.5rem;
    text-align: center;
}
th {
    background: #f5f5f5;
    font-weight: 600;
}
form {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}
input[type="text"], input[type="number"] {
    flex: 1;
    padding: 0.4rem;
    border: 1px solid #ccc;
    border-radius: 3px;
    font-size: 1rem;
}
button {
    padding: 0.4rem 1rem;
    border: none;
    background: #222;
    color: #fff;
    border-radius: 3px;
    cursor: pointer;
    font-size: 1rem;
    transition: background 0.2s;
}
button:hover {
    background: #444;
}
#result {
    font-size: 1rem;
    margin-top: 0.5rem;
    min-height: 1.5em;
}