index.css

body,
html {
    padding: 0;
    margin: 0;
    font-family: sans-serif;
    height: 100vh;
    background: linear-gradient(rgb(0, 98, 255), rgb(36, 0, 128));
    color: white;
    user-select: none;
}

h1 {
    text-align: center;
}

.main-container {
    max-width: 520px;
    margin: auto;
    position: relative;
    top: 20%;
    text-align: center;
    padding: 15px;
    background-color: rgb(78, 8, 8);
    border-radius: 10px;
}

input {
    padding: 10px;
    font-size: 15px;
    border-radius: 8px;
    width: 60%;
    border: none;
    margin-right: 5px;
}

button {
    padding: 10px;
    font-size: 15px;
    border-radius: 8px;
    width: 15%;
    font-weight: bold;
    background-color: black;
    color: aqua;
    border: none;
}

button:hover {
    background-color: aqua;
    color: black;
    cursor: pointer;
}

ul {
    list-style: none;
    padding: 0;
    margin: 10px 0;
    display: flex;
    flex-direction: column;
    margin: 20px 10%;
    gap: 10px;
}

ul li {
    max-width: 95%;
    background-color: blueviolet;
    padding: 10px;
    border-radius: 5px;
    font-weight: bold;
}