add initial marp implementation with sample content and build configuration

node_modules/@marp-team/marpit/lib/postcss/root/rem.js

@@ -0,0 +1,27 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.rem = exports.default = void 0;
+var _postcss_plugin = _interopRequireDefault(require("../../helpers/postcss_plugin"));
+var _font_size = require("./font_size");
+function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
+/** @module */
+
+const skipParsingMatcher = /("[^"]*"|'[^']*'|(?:attr|url|var)\([^)]*\))/g;
+
+/**
+ * Marpit PostCSS rem plugin.
+ *
+ * Replace `rem` unit to calculated value from CSS variable.
+ *
+ * @function rem
+ */
+const rem = exports.rem = (0, _postcss_plugin.default)('marpit-postcss-rem', () => css => css.walkDecls(decl => {
+  decl.value = decl.value.split(skipParsingMatcher).map((v, i) => {
+    if (i % 2) return v;
+    return v.replace(/(\d*\.?\d+)rem\b/g, (_, num) => `calc(var(${_font_size.rootFontSizeCustomProp}, 1rem) * ${num})`);
+  }).join('');
+}));
+var _default = exports.default = rem;