style.css

body, html {
    height: 100%;
}

.container {
    width: auto;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

iframe {
    width: 60%;
    height: 63%;
    border-radius: 0.25rem;
}

.url-loader-container {
    margin-top: 2rem;
    width: 60%;
    display: flex;
    flex-direction: row;
    justify-content: center;
    align-items: center;
}

input.url-input-box {
    width: 40%;
    height: 1.6rem;
    padding: .375rem .75rem;
    font-size: 1rem;
    line-height: 1.5;
    color: #495057;
    border: 1px solid #ced4da;
    border-radius: 0.25rem;
}

button.load-video-button {
    color: #fff;
    line-height: 1.5;
    background-color: #87ceeb;
    padding: .375rem .75rem;
    font-size: 1rem;
    border: 1px solid transparent;
    border-radius: 0.25rem;
    margin: 10px;
}

span.author {
    margin-top: 2rem;
    font-family:  "Arial";
    font-weight: 400;
    color: #495057;
}