Exercism.io -- Hide comment panel to increase readability of code panel

tampermonkey.js

// ==UserScript==
// @name         Exercism panel expand
// @namespace    Exercism
// @version      0.1
// @description  Expand coding panel by hiding the comment panel
// @author       Tim Austin
// @match        https://exercism.io/*/solutions/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    function toggleElement() {
        const hideMessage = "Hide Comment Panel";
        const showMessage = "Show Comment Panel";
        
        const singlePanelClass = 'pure-u-md-1-1';
        const dualPanelClass = 'pure-u-md-1-2';

        const leftPanelQuery = 'div.panels > div.lhs';
        const rightPanelQuery = 'div.panels > div.rhs';

        const leftPanel = document.querySelector(leftPanelQuery);
        const rightPanel = document.querySelector(rightPanelQuery);

        const toggleHtml = `
          <div class="toggle-pane-width">
            <span class="button">${hideMessage}</span>
          </div>`;

        // Create the template element
        const template = document.createElement('template');

        template.innerHTML = toggleHtml.trim();

        //create the toggle div and style it
        const toggleDiv = template.content.firstChild;

        toggleDiv.style.marginBottom = "18px";
        toggleDiv.style.display = "flex";
        toggleDiv.style.justifyContent = "flex-end";


        //create the toggle button and style it
        const toggleButton = toggleDiv.querySelector(".button");

        toggleButton.style.border = "1px solid #CCCCCC";
        toggleButton.style.borderRadius = "3px";
        toggleButton.style.padding = "3px 3px 3px 3px";
        toggleButton.style.backgroundColor = "#EEEEEE";

        toggleButton.addEventListener("click", (e) => {
            if (rightPanel.style.display == "") {
                toggleButton.innerText = showMessage;
                
                rightPanel.style.display = "none";

                leftPanel.classList.remove(dualPanelClass);
                leftPanel.classList.add(singlePanelClass);
            } else {
                toggleButton.innerText = hideMessage;

                rightPanel.style.display = "";

                leftPanel.classList.remove(singlePanelClass);
                leftPanel.classList.add(dualPanelClass);
            }
        });

        return toggleDiv;
    }

    const tabsDiv = document.querySelector('div.panels div.tabs');
    const nextSiblingToTabsDiv = tabsDiv.nextElementSibling;
    const parentContainer = nextSiblingToTabsDiv.parentNode;

    // Insert the new toggle button
    parentContainer.insertBefore(toggleElement(), nextSiblingToTabsDiv);

})();

Install tampermonkey chrome extension (link), copy gist contents to a new script, navigate to a solution, then click the button!