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

body {
    height: 100vh;
    background: #121212;
    display: flex;
    justify-content: center;
    align-items: center;
    font-family: Arial, sans-serif;
}

#container {
    background-color: #1e1e1e;
    border-radius: 20px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.5);
    padding: 20px;
    max-width: 400px;
    width: 90%;
}

input {
    width: 100%;
    height: 80px;
    font-size: 2rem;
    padding: 10px;
    margin-bottom: 20px;
    border-radius: 12px;
    border: none;
    text-align: right;
    background-color: #333;
    color: #fff;
}

#keys {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 15px;
    
}

button {
    height: 70px;
    font-size: 1.5rem;
    border-radius: 12px;
    border: none;
    background-color: orange;
    color: white;
    cursor: pointer;
    transition: background 0.2s;
}

button:hover {
    background-color: #666;
}

button:active {
    transform: scale(0.95);
}