style.css

body {
    background-color: #0f0f0f;
    color: #fff;
    font-family: 'Segoe UI', sans-serif;
    padding: 2em;
}
header {
    text-align: center;
    margin-bottom: 2em;
}
input {
    padding: 0.5em;
    width: 60%;
    margin-right: 1em;
}
button {
    padding: 0.6em 1.2em;
    background: #00ffff;
    border: none;
    color: #000;
    font-weight: bold;
    cursor: pointer;
}
pre {
    background: #1e1e1e;
    padding: 1em;
    margin-top: 1em;
    max-height: 300px;
    overflow-y: auto;
}