feat: turn into custom editor

Closes #67

.gitignore

@@ -4,3 +4,5 @@ node_modules
 *.vsix
 
 .DS_Store
+
+media/bpmn-editor.*

media/reset.css

@@ -0,0 +1,30 @@
+html {
+	box-sizing: border-box;
+	font-size: 13px;
+}
+
+*,
+*:before,
+*:after {
+	box-sizing: inherit;
+}
+
+body,
+h1,
+h2,
+h3,
+h4,
+h5,
+h6,
+p,
+ol,
+ul {
+	margin: 0;
+	padding: 0;
+	font-weight: normal;
+}
+
+img {
+	max-width: 100%;
+	height: auto;
+}

media/vscode.css

@@ -0,0 +1,85 @@
+:root {
+	--container-paddding: 20px;
+	--input-padding-vertical: 6px;
+	--input-padding-horizontal: 4px;
+	--input-margin-vertical: 4px;
+	--input-margin-horizontal: 0;
+}
+
+body {
+	padding: 0;
+	color: var(--vscode-foreground);
+	font-size: var(--vscode-font-size);
+	font-weight: var(--vscode-font-weight);
+	font-family: var(--vscode-font-family);
+	background-color: var(--vscode-editor-background);
+}
+
+ol,
+ul {
+	padding-left: var(--container-paddding);
+}
+
+*:focus {
+	outline-color: var(--vscode-focusBorder) !important;
+}
+
+a {
+	color: var(--vscode-textLink-foreground);
+}
+
+a:hover,
+a:active {
+	color: var(--vscode-textLink-activeForeground);
+}
+
+code {
+	font-size: var(--vscode-editor-font-size);
+	font-family: var(--vscode-editor-font-family);
+}
+
+button {
+	border: none;
+	padding: var(--input-padding-vertical) var(--input-padding-horizontal);
+	width: 100%;
+	text-align: center;
+	outline: 1px solid transparent;
+	outline-offset: 2px !important;
+	color: var(--vscode-button-foreground);
+	background: var(--vscode-button-background);
+}
+
+button:hover {
+	cursor: pointer;
+	background: var(--vscode-button-hoverBackground);
+}
+
+button:focus {
+	outline-color: var(--vscode-focusBorder);
+}
+
+button.secondary {
+	color: var(--vscode-button-secondaryForeground);
+	background: var(--vscode-button-secondaryBackground);
+}
+
+button.secondary:hover {
+	background: var(--vscode-button-secondaryHoverBackground);
+}
+
+input:not([type='checkbox']),
+textarea {
+	display: block;
+	width: 100%;
+	border: none;
+	font-family: var(--vscode-font-family);
+	padding: var(--input-padding-vertical) var(--input-padding-horizontal);
+	color: var(--vscode-input-foreground);
+	outline-color: var(--vscode-input-border);
+	background-color: var(--vscode-input-background);
+}
+
+input::placeholder,
+textarea::placeholder {
+	color: var(--vscode-input-placeholderForeground);
+}