diff --git a/_src/lib/es6-proxy-polyfill.js b/_src/lib/es6-proxy-polyfill.js
new file mode 100644
index 0000000..57c45bb
--- /dev/null
+++ b/_src/lib/es6-proxy-polyfill.js
@@ -0,0 +1,495 @@
+// Constant variables
+var UNDEFINED; // => undefined
+var PROXY_TARGET = "[[ProxyTarget]]";
+var PROXY_HANDLER = "[[ProxyHandler]]";
+var GET = "[[Get]]";
+var SET = "[[Set]]";
+var CALL = "[[Call]]";
+var CONSTRUCT = "[[Construct]]";
+var PROTOTYPE = "__proto__";
+var PROXY_FLAG = "__PROXY__";
+var REVOKED_FLAG = "REVOKED";
+
+var defineProperty = Object.defineProperty;
+var defineProperties = Object.defineProperties;
+var getPrototypeOf = Object.getPrototypeOf;
+var getOwnPropertyDescriptor = Object.getOwnPropertyDescriptor;
+var supportES5 = defineProperties ? isNativeFn(defineProperties) : false;
+
+/**
+ * Return the prototype of proxy object
+ * @param {object} obj
+ * @returns {object}
+ */
+var getProxyProto = supportES5
+  ? Object[PROTOTYPE]
+    ? getPrototypeOf
+    : function (obj) {
+        return typeof obj === "function"
+          ? obj[PROTOTYPE] || {}
+          : getPrototypeOf(obj);
+      }
+  : function (obj) {
+      return (_isVbObject(obj) && _getVbInternalOf(obj)[PROTOTYPE]) || {};
+    };
+
+/**
+ * Check if `value` is a pristine native function
+ * @param {any} value
+ * @returns {boolean}
+ */
+function isNativeFn(value) {
+  return (
+    typeof value === "function" && /\[native code\]/.test(value.toString())
+  );
+}
+
+/**
+ * The Proxy constructor
+ * @constructor
+ * @param {object} target
+ * @param {object} handler
+ */
+function ProxyPolyfill(target, handler) {
+  if (this instanceof ProxyPolyfill) {
+    return createProxy(new Internal(target, handler));
+  } else {
+    throwTypeError("Constructor Proxy requires 'new'");
+  }
+}
+
+/**
+ * Create a revocable Proxy object
+ * @param {object} target
+ * @param {object} handler
+ * @returns {{proxy: object, revoke: function}}
+ */
+ProxyPolyfill.revocable = function (target, handler) {
+  if (this instanceof ProxyPolyfill.revocable) {
+    throwTypeError("Proxy.revocable is not a constructor");
+  }
+  var internal = new Internal(target, handler);
+  var proxy = createProxy(internal);
+  return {
+    proxy: proxy,
+    revoke: function () {
+      internal[PROXY_TARGET] = UNDEFINED;
+      internal[PROXY_HANDLER] = UNDEFINED;
+      if (!supportES5) {
+        getProxyProto(proxy)[PROXY_FLAG] = REVOKED_FLAG;
+      }
+    },
+  };
+};
+
+/**
+ * Create a Proxy object
+ * @param {Internal} internal
+ * @returns {object}
+ */
+function createProxy(internal) {
+  var target = internal[PROXY_TARGET];
+  var proxy;
+  if (typeof target === "function") {
+    proxy = proxyFunction(internal);
+  } else if (target instanceof Array) {
+    proxy = proxyArray(internal);
+  } else {
+    proxy = proxyObject(internal);
+  }
+  return proxy;
+}
+
+/**
+ * Internal data
+ * @constructor
+ * @param {object} target
+ * @param {object} handler
+ */
+function Internal(target, handler) {
+  if (!isObject(target) || !isObject(handler)) {
+    throwTypeError(
+      "Cannot create proxy with a non-object as target or handler",
+    );
+  }
+  if (
+    (getProxyProto(target) && getProxyProto(target)[PROXY_FLAG]) ||
+    (getProxyProto(handler) && getProxyProto(handler)[PROXY_FLAG]) ===
+      REVOKED_FLAG
+  ) {
+    throwTypeError(
+      "Cannot create proxy with a revoked proxy as target or handler",
+    );
+  }
+  this[PROXY_TARGET] = target;
+  this[PROXY_HANDLER] = handler;
+}
+
+/**
+ * The implementation of internal method [[Get]]
+ * @param {string} property
+ * @param {object} receiver
+ * @returns {any}
+ */
+Internal.prototype[GET] = function (property, receiver) {
+  var handler = this[PROXY_HANDLER];
+  validateProxyHanler(handler, "get");
+  if (handler.get == UNDEFINED) {
+    return this[PROXY_TARGET][property];
+  }
+  if (typeof handler.get === "function") {
+    return handler.get(this[PROXY_TARGET], property, receiver);
+  }
+  throwTypeError("Trap 'get' is not a function: " + handler.get);
+};
+
+/**
+ * The implementation of internal method [[Set]]
+ * @param {string} property
+ * @param {any} value
+ * @param {object} receiver
+ */
+Internal.prototype[SET] = function (property, value, receiver) {
+  var handler = this[PROXY_HANDLER];
+  validateProxyHanler(handler, "set");
+  if (handler.set == UNDEFINED) {
+    this[PROXY_TARGET][property] = value;
+  } else if (typeof handler.set === "function") {
+    var result = handler.set(this[PROXY_TARGET], property, value, receiver);
+    if (!result) {
+      // If the set() method returns false in strict-mode code, a TypeError will be thrown.
+      // throwTypeError("Trap 'set' returned false for property '" + property + "'");
+      console.warn("Trap 'set' returned false for property '" + property + "'");
+    }
+    return Boolean(result);
+  } else {
+    throwTypeError("Trap 'set' is not a function: " + handler.set);
+  }
+};
+
+/**
+ * The implementation of internal method [[Call]]
+ * @param {object} thisArg
+ * @param {any[]} argList
+ * @returns {any}
+ */
+Internal.prototype[CALL] = function (thisArg, argList) {
+  var handler = this[PROXY_HANDLER];
+  validateProxyHanler(handler, "apply");
+  if (handler.apply == UNDEFINED) {
+    return this[PROXY_TARGET].apply(thisArg, argList);
+  }
+  if (typeof handler.apply === "function") {
+    return handler.apply(this[PROXY_TARGET], thisArg, argList);
+  }
+  throwTypeError("Trap 'apply' is not a function: " + handler.apply);
+};
+
+/**
+ * The implementation of internal method [[Construct]]
+ * @param {any[]} argList
+ * @param {object} newTarget
+ * @returns {object}
+ */
+Internal.prototype[CONSTRUCT] = function (argList, newTarget) {
+  var handler = this[PROXY_HANDLER];
+  validateProxyHanler(handler, "construct");
+
+  var newObj;
+  if (handler.construct == UNDEFINED) {
+    newObj = evaluateNew(this[PROXY_TARGET], argList);
+  } else if (typeof handler.construct === "function") {
+    newObj = handler.construct(this[PROXY_TARGET], argList, newTarget);
+  } else {
+    throwTypeError("Trap 'construct' is not a function: " + handler.construct);
+  }
+
+  if (isObject(newObj)) {
+    return newObj;
+  } else {
+    throwTypeError("Trap 'construct' returned non-object: " + newObj);
+  }
+};
+
+/**
+ * Validate the proxy hanler
+ * @param {object} handler
+ * @param {string} trap
+ */
+function validateProxyHanler(handler, trap) {
+  if (!handler) {
+    throwTypeError(
+      "Cannot perform '" + trap + "' on a proxy that has been revoked",
+    );
+  }
+}
+
+/**
+ * Call constructor with 'new'
+ * @param {function} F constructor
+ * @param {any[]} argList
+ * @returns {object}
+ */
+function evaluateNew(F, argList) {
+  var params = [];
+  for (var i = 0, len = argList.length; i < len; ++i) {
+    params.push("args[" + i + "]");
+  }
+  var executor = new Function(
+    "Ctor",
+    "args",
+    "return new Ctor(" + params.join(", ") + ")",
+  );
+  return executor(F, argList);
+}
+
+/**
+ * Throw a type error
+ * @param {string} message
+ */
+function throwTypeError(message) {
+  throw new TypeError(message);
+}
+
+/**
+ * Check if value is the language type of Object
+ * @param {any} value
+ * @returns {boolean}
+ */
+function isObject(value) {
+  return value
+    ? typeof value === "object" || typeof value === "function"
+    : false;
+}
+
+/**
+ * Check if key is an own property of object
+ * @param {object} obj
+ * @param {string} key
+ * @returns {boolean}
+ */
+function hasOwnProperty(obj, key) {
+  return Object.prototype.hasOwnProperty.call(obj, key);
+}
+
+/**
+ * Hack `Object.getOwnPropertyNames`
+ */
+var getOwnPropertyNames =
+  Object.getOwnPropertyNames ||
+  function (obj) {
+    var names = [];
+    for (var key in obj) {
+      if (hasOwnProperty(obj, key)) {
+        names.push(key);
+      }
+    }
+    return names;
+  };
+
+/**
+ * Set the prototype of function
+ * @param {function} fn
+ * @param {object} proto
+ * @returns {object}
+ */
+var setFuncProto = isNativeFn(Object.setPrototypeOf)
+  ? Object.setPrototypeOf
+  : Object[PROTOTYPE]
+    ? function (fn, proto) {
+        fn[PROTOTYPE] = proto;
+        return fn;
+      }
+    : function (fn, proto) {
+        return defineProperty(fn, PROTOTYPE, { value: proto });
+      };
+
+/**
+ * Hack `Object.create`
+ */
+var objectCreate = supportES5
+  ? Object.create
+  : function (_, props) {
+      var obj = defineProperties({}, props);
+      if (_isVbObject(obj)) {
+        var proto = {};
+        proto[PROXY_FLAG] = UNDEFINED;
+        _getVbInternalOf(obj)[PROTOTYPE] = proto;
+      }
+      return obj;
+    };
+
+/**
+ * Hack `Object.assign`
+ */
+var objectAssign =
+  Object.assign ||
+  function (target, source) {
+    for (var key in source) {
+      if (hasOwnProperty(source, key)) {
+        target[key] = source[key];
+      }
+    }
+    return target;
+  };
+
+/**
+ * Proxy function
+ * @param {Internal} internal
+ * @returns {function}
+ */
+function proxyFunction(internal) {
+  var target = internal[PROXY_TARGET];
+
+  function P() {
+    return this instanceof P
+      ? internal[CONSTRUCT](arguments, P)
+      : internal[CALL](this, arguments);
+  }
+  P.prototype = target.prototype; // `prototype` is not configurable
+
+  if (supportES5) {
+    var descMap = observeProto(internal);
+    var newProto = objectCreate(getPrototypeOf(target), descMap);
+    setFuncProto(P, newProto);
+
+    descMap = observeProperties(target, internal);
+    for (var key in descMap) {
+      if (hasOwnProperty(P, key)) delete descMap[key];
+    }
+    defineProperties(P, descMap);
+  } else {
+    objectAssign(P, target);
+  }
+
+  return P;
+}
+
+/**
+ * Proxy array
+ * @param {Internal} internal
+ * @returns {object} array-like object
+ */
+function proxyArray(internal) {
+  var target = internal[PROXY_TARGET];
+
+  var descMap, newProto;
+  if (supportES5) {
+    descMap = observeProto(internal);
+    // Fix: `concat` does not work correctly on array-like object
+    descMap.concat.get = function () {
+      var val = internal[GET]("concat", this);
+      return val === Array.prototype.concat ? val.bind(target) : val;
+    };
+    newProto = objectCreate(getPrototypeOf(target), descMap);
+  }
+
+  descMap = observeProperties(target, internal);
+  // Observe the change of `length`, and synchronize
+  // the properties of Proxy object to target array
+  descMap.length.set = function (value) {
+    var lenDiff = value - target.length;
+    internal[SET]("length", value, this);
+    if (lenDiff) syncArrayElement(lenDiff, this, internal);
+  };
+
+  return objectCreate(newProto, descMap);
+}
+
+/**
+ * Proxy object
+ * @param {Internal} internal
+ * @returns {object}
+ */
+function proxyObject(internal) {
+  var target = internal[PROXY_TARGET];
+  var descMap, newProto;
+  if (supportES5) {
+    descMap = observeProto(internal);
+    newProto = objectCreate(getPrototypeOf(target), descMap);
+  }
+
+  descMap = observeProperties(target, internal);
+  return objectCreate(newProto, descMap);
+}
+
+/**
+ * Observe [[Prototype]]
+ * @param {Internal} internal
+ * @returns {object} descriptors
+ */
+function observeProto(internal) {
+  var descMap = {};
+  var proto = internal[PROXY_TARGET];
+  while ((proto = getPrototypeOf(proto))) {
+    var props = observeProperties(proto, internal);
+    objectAssign(descMap, props);
+  }
+  descMap[PROXY_FLAG] = {
+    get: function () {
+      return internal[PROXY_TARGET] ? UNDEFINED : REVOKED_FLAG;
+    },
+  };
+  return descMap;
+}
+
+/**
+ * Observe properties
+ * @param {object} obj
+ * @param {Internal} internal
+ * @returns {object} descriptors
+ */
+function observeProperties(obj, internal) {
+  var names = getOwnPropertyNames(obj);
+  var descMap = {};
+  for (var i = names.length - 1; i >= 0; --i) {
+    descMap[names[i]] = observeProperty(obj, names[i], internal);
+  }
+  return descMap;
+}
+
+/**
+ * Observe property
+ * @param {object} obj
+ * @param {string} prop
+ * @param {Internal} internal
+ * @returns {{get: function, set: function, enumerable: boolean, configurable: boolean}}
+ */
+function observeProperty(obj, prop, internal) {
+  var desc = getOwnPropertyDescriptor(obj, prop);
+  return {
+    get: function () {
+      return internal[GET](prop, this);
+    },
+    set: function (value) {
+      internal[SET](prop, value, this);
+    },
+    enumerable: desc.enumerable,
+    configurable: desc.configurable,
+  };
+}
+
+/**
+ * Sync array element from P to target
+ * @param {number} lenDiff
+ * @param {object} P
+ * @param {Internal} internal
+ */
+function syncArrayElement(lenDiff, P, internal) {
+  var target = internal[PROXY_TARGET];
+  if (lenDiff > 0) {
+    for (var tLen = target.length, i = tLen - lenDiff; i < tLen; ++i) {
+      var desc = getOwnPropertyDescriptor(P, i);
+      if (desc) defineProperty(target, i, desc);
+      else target[i] = UNDEFINED;
+      desc = observeProperty(target, i, internal);
+      defineProperty(P, i, desc);
+    }
+  } else {
+    for (var i = target.length, pLen = i - lenDiff; i < pLen; ++i) {
+      delete P[i];
+    }
+  }
+}
+
+export default typeof Proxy === "undefined" ? ProxyPolyfill : Proxy;
diff --git a/_src/lib/legacy-polyfill.js b/_src/lib/legacy-polyfill.js
new file mode 100644
index 0000000..96f220e
--- /dev/null
+++ b/_src/lib/legacy-polyfill.js
@@ -0,0 +1,14 @@
+import Es6ProxyPolyfill from "./es6-proxy-polyfill.js";
+import "promise-polyfill/src/polyfill";
+import "whatwg-fetch";
+import "events-polyfill";
+import "element-polyfill";
+import "@webcomponents/template/template.min.js";
+
+const globalObj =
+  (typeof globalThis !== "undefined" && globalThis) ||
+  (typeof self !== "undefined" && self) ||
+  // eslint-disable-next-line no-undef
+  (typeof global !== "undefined" && global) ||
+  {};
+globalObj.Proxy = typeof Proxy === "undefined" ? Es6ProxyPolyfill : Proxy;
diff --git a/_vite.config.mjs b/_vite.config.mjs
index 2a00a93..2245e87 100644
--- a/_vite.config.mjs
+++ b/_vite.config.mjs
@@ -107,6 +107,9 @@ export default defineConfig(({mode})=>({
     }),
     legacy({
       targets: [],
+      additionalLegacyPolyfills: [
+        resolve(__dirname, '_src/lib/legacy-polyfill.js'),
+      ],
     }),
     visualizer({
       filename: '_stats.html',
diff --git a/package-lock.json b/package-lock.json
index 16a8573..d2d0ce0 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -8,12 +8,16 @@
       "dependencies": {
         "@vitejs/plugin-legacy": "^5.3.2",
         "@vitejs/plugin-vue": "^5.0.4",
+        "@webcomponents/template": "^1.5.1",
         "bootstrap": "^5.3.3",
+        "element-polyfill": "^1.1.0",
+        "events-polyfill": "^2.1.2",
         "highlight.js": "^11.9.0",
         "lato-webfont": "^2.15.1",
         "liquidjs": "^10.10.2",
         "markup-js": "^1.5.21",
         "mustache": "^4.2.0",
+        "promise-polyfill": "^8.3.0",
         "sass": "^1.74.1",
         "sass-cast": "^0.5.6",
         "source-code-pro": "^2.38.0",
@@ -22,7 +26,8 @@
         "unplugin-vue-components": "^0.26.0",
         "vite": "^5.2.8",
         "vite-plugin-ruby": "^5.0.0",
-        "webfontloader": "^1.6.28"
+        "webfontloader": "^1.6.28",
+        "whatwg-fetch": "^3.6.20"
       },
       "devDependencies": {
         "prettier": "^3.2.5",
@@ -2393,6 +2398,11 @@
       "integrity": "sha512-PuJe7vDIi6VYSinuEbUIQgMIRZGgM8e4R+G+/dQTk0X1NEdvgvvgv7m+rfmDH1gZzyA1OjjoWskvHlfRNfQf3g==",
       "peer": true
     },
+    "node_modules/@webcomponents/template": {
+      "version": "1.5.1",
+      "resolved": "https://registry.npmjs.org/@webcomponents/template/-/template-1.5.1.tgz",
+      "integrity": "sha512-3e8bx+bgRhyuRwFrDGu7CalILomo11ixuMzVGvpXSxL8lX+ijCIG6J3kS4O/7nElVuKE7vkuXB1xD+RICDNCCg=="
+    },
     "node_modules/acorn": {
       "version": "8.11.3",
       "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.11.3.tgz",
@@ -2728,6 +2738,11 @@
       "resolved": "https://registry.npmjs.org/electron-to-chromium/-/electron-to-chromium-1.4.729.tgz",
       "integrity": "sha512-bx7+5Saea/qu14kmPTDHQxkp2UnziG3iajUQu3BxFvCOnpAJdDbMV4rSl+EqFDkkpNNVUFlR1kDfpL59xfy1HA=="
     },
+    "node_modules/element-polyfill": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/element-polyfill/-/element-polyfill-1.1.0.tgz",
+      "integrity": "sha512-t+hZSDS8by+uMyFwGXo8cn6Jf5VM7AjY+p2ZGg1s/E7vA3VmuVFJjKJO3GIPAgH3HfUm/9codl8yGo3GgcMH2A=="
+    },
     "node_modules/emoji-regex": {
       "version": "8.0.0",
       "resolved": "https://registry.npmjs.org/emoji-regex/-/emoji-regex-8.0.0.tgz",
@@ -2812,6 +2827,11 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/events-polyfill": {
+      "version": "2.1.2",
+      "resolved": "https://registry.npmjs.org/events-polyfill/-/events-polyfill-2.1.2.tgz",
+      "integrity": "sha512-vx4kpGzymyD3CEjmg2wTQA6k5e0RhGTkX3ZwfC9m/Ol7+me2tbVuJ0GjSd8eIJxFioubicA0nUL0SIOAyfrgZA=="
+    },
     "node_modules/fast-glob": {
       "version": "3.3.2",
       "resolved": "https://registry.npmjs.org/fast-glob/-/fast-glob-3.3.2.tgz",
@@ -3290,6 +3310,11 @@
         "url": "https://github.com/prettier/prettier?sponsor=1"
       }
     },
+    "node_modules/promise-polyfill": {
+      "version": "8.3.0",
+      "resolved": "https://registry.npmjs.org/promise-polyfill/-/promise-polyfill-8.3.0.tgz",
+      "integrity": "sha512-H5oELycFml5yto/atYqmjyigJoAo3+OXwolYiH7OfQuYlAqhxNvTfiNMbV9hsC6Yp83yE5r2KTVmtrG6R9i6Pg=="
+    },
     "node_modules/queue-microtask": {
       "version": "1.2.3",
       "resolved": "https://registry.npmjs.org/queue-microtask/-/queue-microtask-1.2.3.tgz",
@@ -3885,6 +3910,11 @@
       "resolved": "https://registry.npmjs.org/webpack-virtual-modules/-/webpack-virtual-modules-0.6.1.tgz",
       "integrity": "sha512-poXpCylU7ExuvZK8z+On3kX+S8o/2dQ/SVYueKA0D4WEMXROXgY8Ez50/bQEUmvoSMMrWcrJqCHuhAbsiwg7Dg=="
     },
+    "node_modules/whatwg-fetch": {
+      "version": "3.6.20",
+      "resolved": "https://registry.npmjs.org/whatwg-fetch/-/whatwg-fetch-3.6.20.tgz",
+      "integrity": "sha512-EqhiFU6daOA8kpjOWTL0olhVOF3i7OrFzSYiGsEMB8GcXS+RrzauAERX65xMeNWVqxA6HXH2m69Z9LaKKdisfg=="
+    },
     "node_modules/wrap-ansi": {
       "version": "7.0.0",
       "resolved": "https://registry.npmjs.org/wrap-ansi/-/wrap-ansi-7.0.0.tgz",
diff --git a/package.json b/package.json
index 8d3e7b3..a574430 100644
--- a/package.json
+++ b/package.json
@@ -8,12 +8,16 @@
   "dependencies": {
     "@vitejs/plugin-legacy": "^5.3.2",
     "@vitejs/plugin-vue": "^5.0.4",
+    "@webcomponents/template": "^1.5.1",
     "bootstrap": "^5.3.3",
+    "element-polyfill": "^1.1.0",
+    "events-polyfill": "^2.1.2",
     "highlight.js": "^11.9.0",
     "lato-webfont": "^2.15.1",
     "liquidjs": "^10.10.2",
     "markup-js": "^1.5.21",
     "mustache": "^4.2.0",
+    "promise-polyfill": "^8.3.0",
     "sass": "^1.74.1",
     "sass-cast": "^0.5.6",
     "source-code-pro": "^2.38.0",
@@ -22,7 +26,8 @@
     "unplugin-vue-components": "^0.26.0",
     "vite": "^5.2.8",
     "vite-plugin-ruby": "^5.0.0",
-    "webfontloader": "^1.6.28"
+    "webfontloader": "^1.6.28",
+    "whatwg-fetch": "^3.6.20"
   },
   "devDependencies": {
     "prettier": "^3.2.5",