github_corner.js

function GithubCornerTopRight(
    url = "https://github.com/pomodorozhong/github-corners",
    backgroundColor = "#151513",
    foregroundColor = "#ffffff"
) {
    let container = document.createElement("div");
    document.body.appendChild(container);

    // Create a shadow root
    let shadowRoot = container.attachShadow({ mode: "open" });

    let wrapper = document.createElement("div");
    wrapper.innerHTML = `
        <div class="github-corner">
            <svg width="80" height="80" viewBox="0 0 250 250" style="fill:${backgroundColor}; color:${foregroundColor}; position: absolute; top: 0; border: 0; right: 0;" aria-hidden="true">
                <a href="${url}" style="pointer-events:auto">
                    <path d="M0,0 L250,250 L250,0 Z"></path>
                </a>
                <path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path>
                <path d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2" fill="currentColor" style="transform-origin: 130px 106px;"
                class="octo-arm"></path>
                <path d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4 L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0 C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6 C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1 C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9 141.8,141.8 Z"
                fill="currentColor" class="octo-body"></path>
            </svg>
        </div>`;

    // Create some CSS to apply to the shadow dom
    let style = document.createElement("style");
    style.textContent = `
        .github-corner:hover .octo-arm {
            animation: octocat-wave 560ms ease-in-out
        }
        
        .github-corner {
            pointer-events: none
        }
        
        @keyframes octocat-wave {
            0%,
            100% {
                transform: rotate(0)
            }
            20%,
            60% {
                transform: rotate(-25deg)
            }
            40%,
            80% {
                transform: rotate(10deg)
            }
        }
        
        @media (max-width:500px) {
            .github-corner:hover .octo-arm {
                animation: none
            }
            .github-corner .octo-arm {
                animation: octocat-wave 560ms ease-in-out
            }
        }`;
    shadowRoot.appendChild(style);
    shadowRoot.appendChild(wrapper);
}

// white on black
let your_url = "https://github.com/pomodorozhong/github-corners";
GithubCornerTopRight(your_url);

// black on white
// GithubCornerTopRight(your_url, "#ffffff", "#000000");