Use monaco editor in demo

docs/assets/js/vs/editor/editor.main.css

@@ -0,0 +1,6 @@
+/*!-----------------------------------------------------------
+ * Copyright (c) Microsoft Corporation. All rights reserved.
+ * Version: 0.30.1(829382514cb1065f5ebb90f436e1c6103e153953)
+ * Released under the MIT license
+ * https://github.com/microsoft/vscode/blob/main/LICENSE.txt
+ *-----------------------------------------------------------*/.monaco-action-bar{white-space:nowrap;height:100%}.monaco-action-bar .actions-container{display:flex;margin:0 auto;padding:0;height:100%;width:100%;align-items:center}.monaco-action-bar.vertical .actions-container{display:inline-block}.monaco-action-bar .action-item{display:block;align-items:center;justify-content:center;cursor:pointer;position:relative}.monaco-action-bar .action-item.disabled{cursor:default}.monaco-action-bar .action-item .codicon,.monaco-action-bar .action-item .icon{display:block}.monaco-action-bar .action-item .codicon{display:flex;align-items:center;width:16px;height:16px}.monaco-action-bar .action-label{font-size:11px;padding:3px;border-radius:5px}.monaco-action-bar .action-item.disabled .action-label,.monaco-action-bar .action-item.disabled .action-label:before,.monaco-action-bar .action-item.disabled .action-label:hover{opacity:.4}.monaco-action-bar.vertical{text-align:left}.monaco-action-bar.vertical .action-item{display:block}.monaco-action-bar.vertical .action-label.separator{display:block;border-bottom:1px solid #bbb;padding-top:1px;margin-left:.8em;margin-right:.8em}.monaco-action-bar .action-item .action-label.separator{width:1px;height:16px;margin:5px 4px!important;cursor:default;min-width:1px;padding:0;background-color:#bbb}.secondary-actions .monaco-action-bar .action-label{margin-left:6px}.monaco-action-bar .action-item.select-container{overflow:hidden;flex:1;max-width:170px;min-width:60px;display:flex;align-items:center;justify-content:center;margin-right:10px}.monaco-action-bar .action-item.action-dropdown-item{display:flex}.monaco-action-bar .action-item.action-dropdown-item>.action-label{margin-right:1px}.monaco-aria-container{position:absolute;left:-999em}.monaco-text-button{box-sizing:border-box;display:flex;width:100%;padding:4px;text-align:center;cursor:pointer;justify-content:center;align-items:center}.monaco-text-button:focus{outline-offset:2px!important}.monaco-text-button:hover{text-decoration:none!important}.monaco-button.disabled,.monaco-button.disabled:focus{opacity:.4!important;cursor:default}.monaco-text-button>.codicon{margin:0 .2em;color:inherit!important}.monaco-button-dropdown{display:flex;cursor:pointer}.monaco-button-dropdown>.monaco-dropdown-button{margin-left:1px}.monaco-description-button{flex-direction:column}.monaco-description-button .monaco-button-label{font-weight:500}.monaco-description-button .monaco-button-description{font-style:italic}.monaco-custom-checkbox{margin-left:2px;float:left;cursor:pointer;overflow:hidden;opacity:.7;width:20px;height:20px;border:1px solid transparent;padding:1px;box-sizing:border-box;user-select:none;-webkit-user-select:none;-ms-user-select:none}.monaco-custom-checkbox.checked,.monaco-custom-checkbox:hover{opacity:1}.hc-black .monaco-custom-checkbox,.hc-black .monaco-custom-checkbox:hover{background:none}.monaco-custom-checkbox.monaco-simple-checkbox{height:18px;width:18px;border:1px solid transparent;border-radius:3px;margin-right:9px;margin-left:0;padding:0;opacity:1;background-size:16px!important}.monaco-custom-checkbox.monaco-simple-checkbox:not(.checked):before{visibility:hidden}@font-face{font-family:codicon;font-display:block;src:url(../base/browser/ui/codicons/codicon/codicon.ttf) format("truetype")}.codicon[class*=codicon-]{font:normal normal normal 16px/1 codicon;display:inline-block;text-decoration:none;text-rendering:auto;text-align:center;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;user-select:none;-webkit-user-select:none;-ms-user-select:none}.codicon-wrench-subaction{opacity:.5}@keyframes codicon-spin{to{transform:rotate(1turn)}}.codicon-gear.codicon-modifier-spin,.codicon-loading.codicon-modifier-spin,.codicon-notebook-state-executing.codicon-modifier-spin,.codicon-sync.codicon-modifier-spin{animation:codicon-spin 1.5s steps(30) infinite}.codicon-modifier-disabled{opacity:.4}.codicon-loading,.codicon-tree-item-loading:before{animation-duration:1s!important;animation-timing-function:cubic-bezier(.53,.21,.29,.67)!important}.context-view{position:absolute;z-index:2500}.context-view.fixed{all:initial;font-family:inherit;font-size:13px;position:fixed;z-index:2500;color:inherit}.monaco-count-badge{padding:3px 6px;border-radius:11px;font-size:11px;min-width:18px;min-height:18px;line-height:11px;font-weight:400;text-align:center;display:inline-block;box-sizing:border-box}.monaco-count-badge.long{padding:2px 3px;border-radius:2px;min-height:auto;line-height:normal}.monaco-dropdown{height:100%;padding:0}.monaco-dropdown>.dropdown-label{cursor:pointer;height:100%;display:flex;align-items:center;justify-content:center}.monaco-dropdown>.dropdown-label>.action-label.disabled{cursor:default}.monaco-dropdown-with-primary{display:flex!important;flex-direction:row;border-radius:5px}.monaco-dropdown-with-primary>.action-container>.action-label{margin-right:0}.monaco-dropdown-with-primary>.dropdown-action-container>.monaco-dropdLine truncated