diff --git a/README.md b/README.md
index 67b4299..17e976a 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,7 @@
 - [x] 支持链接微信图文，外链自动转为文末索引
 - [x] 支持一键复制并粘贴到公众号后台
 - [x] 支持图片上传并将 URL 插入编辑器光标定位处
+- [ ] 实现自定义 CSS 并实时渲染（待开发）
 
 ![select-and-replace-color-theme](./assets/images/select-and-replace-color-theme.gif)
 
diff --git a/libs/css/show-hint.css b/libs/css/show-hint.css
new file mode 100644
index 0000000..5617ccc
--- /dev/null
+++ b/libs/css/show-hint.css
@@ -0,0 +1,36 @@
+.CodeMirror-hints {
+  position: absolute;
+  z-index: 10;
+  overflow: hidden;
+  list-style: none;
+
+  margin: 0;
+  padding: 2px;
+
+  -webkit-box-shadow: 2px 3px 5px rgba(0,0,0,.2);
+  -moz-box-shadow: 2px 3px 5px rgba(0,0,0,.2);
+  box-shadow: 2px 3px 5px rgba(0,0,0,.2);
+  border-radius: 3px;
+  border: 1px solid silver;
+
+  background: white;
+  font-size: 90%;
+  font-family: monospace;
+
+  max-height: 20em;
+  overflow-y: auto;
+}
+
+.CodeMirror-hint {
+  margin: 0;
+  padding: 0 4px;
+  border-radius: 2px;
+  white-space: pre;
+  color: black;
+  cursor: pointer;
+}
+
+li.CodeMirror-hint-active {
+  background: #08f;
+  color: white;
+}
diff --git a/libs/scripts/css-hint.js b/libs/scripts/css-hint.js
new file mode 100644
index 0000000..980d119
--- /dev/null
+++ b/libs/scripts/css-hint.js
@@ -0,0 +1,66 @@
+// CodeMirror, copyright (c) by Marijn Haverbeke and others
+// Distributed under an MIT license: https://codemirror.net/LICENSE
+
+(function(mod) {
+  if (typeof exports == "object" && typeof module == "object") // CommonJS
+    mod(require("../../lib/codemirror"), require("../../mode/css/css"));
+  else if (typeof define == "function" && define.amd) // AMD
+    define(["../../lib/codemirror", "../../mode/css/css"], mod);
+  else // Plain browser env
+    mod(CodeMirror);
+})(function(CodeMirror) {
+  "use strict";
+
+  var pseudoClasses = {"active":1, "after":1, "before":1, "checked":1, "default":1,
+    "disabled":1, "empty":1, "enabled":1, "first-child":1, "first-letter":1,
+    "first-line":1, "first-of-type":1, "focus":1, "hover":1, "in-range":1,
+    "indeterminate":1, "invalid":1, "lang":1, "last-child":1, "last-of-type":1,
+    "link":1, "not":1, "nth-child":1, "nth-last-child":1, "nth-last-of-type":1,
+    "nth-of-type":1, "only-of-type":1, "only-child":1, "optional":1, "out-of-range":1,
+    "placeholder":1, "read-only":1, "read-write":1, "required":1, "root":1,
+    "selection":1, "target":1, "valid":1, "visited":1
+  };
+
+  CodeMirror.registerHelper("hint", "css", function(cm) {
+    var cur = cm.getCursor(), token = cm.getTokenAt(cur);
+    var inner = CodeMirror.innerMode(cm.getMode(), token.state);
+    if (inner.mode.name != "css") return;
+
+    if (token.type == "keyword" && "!important".indexOf(token.string) == 0)
+      return {list: ["!important"], from: CodeMirror.Pos(cur.line, token.start),
+              to: CodeMirror.Pos(cur.line, token.end)};
+
+    var start = token.start, end = cur.ch, word = token.string.slice(0, end - start);
+    if (/[^\w$_-]/.test(word)) {
+      word = ""; start = end = cur.ch;
+    }
+
+    var spec = CodeMirror.resolveMode("text/css");
+
+    var result = [];
+    function add(keywords) {
+      for (var name in keywords)
+        if (!word || name.lastIndexOf(word, 0) == 0)
+          result.push(name);
+    }
+
+    var st = inner.state.state;
+    if (st == "pseudo" || token.type == "variable-3") {
+      add(pseudoClasses);
+    } else if (st == "block" || st == "maybeprop") {
+      add(spec.propertyKeywords);
+    } else if (st == "prop" || st == "parens" || st == "at" || st == "params") {
+      add(spec.valueKeywords);
+      add(spec.colorKeywords);
+    } else if (st == "media" || st == "media_parens") {
+      add(spec.mediaTypes);
+      add(spec.mediaFeatures);
+    }
+
+    if (result.length) return {
+      list: result,
+      from: CodeMirror.Pos(cur.line, start),
+      to: CodeMirror.Pos(cur.line, end)
+    };
+  });
+});
diff --git a/libs/scripts/show-hint.js b/libs/scripts/show-hint.js
new file mode 100644
index 0000000..d70b2ab
--- /dev/null
+++ b/libs/scripts/show-hint.js
@@ -0,0 +1,460 @@
+// CodeMirror, copyright (c) by Marijn Haverbeke and others
+// Distributed under an MIT license: https://codemirror.net/LICENSE
+
+(function(mod) {
+  if (typeof exports == "object" && typeof module == "object") // CommonJS
+    mod(require("../../lib/codemirror"));
+  else if (typeof define == "function" && define.amd) // AMD
+    define(["../../lib/codemirror"], mod);
+  else // Plain browser env
+    mod(CodeMirror);
+})(function(CodeMirror) {
+  "use strict";
+
+  var HINT_ELEMENT_CLASS        = "CodeMirror-hint";
+  var ACTIVE_HINT_ELEMENT_CLASS = "CodeMirror-hint-active";
+
+  // This is the old interface, kept around for now to stay
+  // backwards-compatible.
+  CodeMirror.showHint = function(cm, getHints, options) {
+    if (!getHints) return cm.showHint(options);
+    if (options && options.async) getHints.async = true;
+    var newOpts = {hint: getHints};
+    if (options) for (var prop in options) newOpts[prop] = options[prop];
+    return cm.showHint(newOpts);
+  };
+
+  CodeMirror.defineExtension("showHint", function(options) {
+    options = parseOptions(this, this.getCursor("start"), options);
+    var selections = this.listSelections()
+    if (selections.length > 1) return;
+    // By default, don't allow completion when something is selected.
+    // A hint function can have a `supportsSelection` property to
+    // indicate that it can handle selections.
+    if (this.somethingSelected()) {
+      if (!options.hint.supportsSelection) return;
+      // Don't try with cross-line selections
+      for (var i = 0; i < selections.length; i++)
+        if (selections[i].head.line != selections[i].anchor.line) return;
+    }
+
+    if (this.state.completionActive) this.state.completionActive.close();
+    var completion = this.state.completionActive = new Completion(this, options);
+    if (!completion.options.hint) return;
+
+    CodeMirror.signal(this, "startCompletion", this);
+    completion.update(true);
+  });
+
+  CodeMirror.defineExtension("closeHint", function() {
+    if (this.state.completionActive) this.state.completionActive.close()
+  })
+
+  function Completion(cm, options) {
+    this.cm = cm;
+    this.options = options;
+    this.widget = null;
+    this.debounce = 0;
+    this.tick = 0;
+    this.startPos = this.cm.getCursor("start");
+    this.startLen = this.cm.getLine(this.startPos.line).length - this.cm.getSelection().length;
+
+    var self = this;
+    cm.on("cursorActivity", this.activityFunc = function() { self.cursorActivity(); });
+  }
+
+  var requestAnimationFrame = window.requestAnimationFrame || function(fn) {
+    return setTimeout(fn, 1000/60);
+  };
+  var cancelAnimationFrame = window.cancelAnimationFrame || clearTimeout;
+
+  Completion.prototype = {
+    close: function() {
+      if (!this.active()) return;
+      this.cm.state.completionActive = null;
+      this.tick = null;
+      this.cm.off("cursorActivity", this.activityFunc);
+
+      if (this.widget && this.data) CodeMirror.signal(this.data, "close");
+      if (this.widget) this.widget.close();
+      CodeMirror.signal(this.cm, "endCompletion", this.cm);
+    },
+
+    active: function() {
+      return this.cm.state.completionActive == this;
+    },
+
+    pick: function(data, i) {
+      var completion = data.list[i];
+      if (completion.hint) completion.hint(this.cm, data, completion);
+      else this.cm.replaceRange(getText(completion), completion.from || data.from,
+                                completion.to || data.to, "complete");
+      CodeMirror.signal(data, "pick", completion);
+      this.close();
+    },
+
+    cursorActivity: function() {
+      if (this.debounce) {
+        cancelAnimationFrame(this.debounce);
+        this.debounce = 0;
+      }
+
+      var pos = this.cm.getCursor(), line = this.cm.getLine(pos.line);
+      if (pos.line != this.startPos.line || line.length - pos.ch != this.startLen - this.startPos.ch ||
+          pos.ch < this.startPos.ch || this.cm.somethingSelected() ||
+          (!pos.ch || this.options.closeCharacters.test(line.charAt(pos.ch - 1)))) {
+        this.close();
+      } else {
+        var self = this;
+        this.debounce = requestAnimationFrame(function() {self.update();});
+        if (this.widget) this.widget.disable();
+      }
+    },
+
+    update: function(first) {
+      if (this.tick == null) return
+      var self = this, myTick = ++this.tick
+      fetchHints(this.options.hint, this.cm, this.options, function(data) {
+        if (self.tick == myTick) self.finishUpdate(data, first)
+      })
+    },
+
+    finishUpdate: function(data, first) {
+      if (this.data) CodeMirror.signal(this.data, "update");
+
+      var picked = (this.widget && this.widget.picked) || (first && this.options.completeSingle);
+      if (this.widget) this.widget.close();
+
+      this.data = data;
+
+      if (data && data.list.length) {
+        if (picked && data.list.length == 1) {
+          this.pick(data, 0);
+        } else {
+          this.widget = new Widget(this, data);
+          CodeMirror.signal(data, "shown");
+        }
+      }
+    }
+  };
+
+  function parseOptions(cm, pos, options) {
+    var editor = cm.options.hintOptions;
+    var out = {};
+    for (var prop in defaultOptions) out[prop] = defaultOptions[prop];
+    if (editor) for (var prop in editor)
+      if (editor[prop] !== undefined) out[prop] = editor[prop];
+    if (options) for (var prop in options)
+      if (options[prop] !== undefined) out[prop] = options[prop];
+    if (out.hint.resolve) out.hint = out.hint.resolve(cm, pos)
+    return out;
+  }
+
+  function getText(completion) {
+    if (typeof completion == "string") return completion;
+    else return completion.text;
+  }
+
+  function buildKeyMap(completion, handle) {
+    var baseMap = {
+      Up: function() {handle.moveFocus(-1);},
+      Down: function() {handle.moveFocus(1);},
+      PageUp: function() {handle.moveFocus(-handle.menuSize() + 1, true);},
+      PageDown: function() {handle.moveFocus(handle.menuSize() - 1, true);},
+      Home: function() {handle.setFocus(0);},
+      End: function() {handle.setFocus(handle.length - 1);},
+      Enter: handle.pick,
+      Tab: handle.pick,
+      Esc: handle.close
+    };
+
+    var mac = /Mac/.test(navigator.platform);
+
+    if (mac) {
+      baseMap["Ctrl-P"] = function() {handle.moveFocus(-1);};
+      baseMap["Ctrl-N"] = function() {handle.moveFocus(1);};
+    }
+
+    var custom = completion.options.customKeys;
+    var ourMap = custom ? {} : baseMap;
+    function addBinding(key, val) {
+      var bound;
+      if (typeof val != "string")
+        bound = function(cm) { return val(cm, handle); };
+      // This mechanism is deprecated
+      else if (baseMap.hasOwnProperty(val))
+        bound = baseMap[val];
+      else
+        bound = val;
+      ourMap[key] = bound;
+    }
+    if (custom)
+      for (var key in custom) if (custom.hasOwnProperty(key))
+        addBinding(key, custom[key]);
+    var extra = completion.options.extraKeys;
+    if (extra)
+      for (var key in extra) if (extra.hasOwnProperty(key))
+        addBinding(key, extra[key]);
+    return ourMap;
+  }
+
+  function getHintElement(hintsElement, el) {
+    while (el && el != hintsElement) {
+      if (el.nodeName.toUpperCase() === "LI" && el.parentNode == hintsElement) return el;
+      el = el.parentNode;
+    }
+  }
+
+  function Widget(completion, data) {
+    this.completion = completion;
+    this.data = data;
+    this.picked = false;
+    var widget = this, cm = completion.cm;
+    var ownerDocument = cm.getInputField().ownerDocument;
+    var parentWindow = ownerDocument.defaultView || ownerDocument.parentWindow;
+
+    var hints = this.hints = ownerDocument.createElement("ul");
+    var theme = completion.cm.options.theme;
+    hints.className = "CodeMirror-hints " + theme;
+    this.selectedHint = data.selectedHint || 0;
+
+    var completions = data.list;
+    for (var i = 0; i < completions.length; ++i) {
+      var elt = hints.appendChild(ownerDocument.createElement("li")), cur = completions[i];
+      var className = HINT_ELEMENT_CLASS + (i != this.selectedHint ? "" : " " + ACTIVE_HINT_ELEMENT_CLASS);
+      if (cur.className != null) className = cur.className + " " + className;
+      elt.className = className;
+      if (cur.render) cur.render(elt, data, cur);
+      else elt.appendChild(ownerDocument.createTextNode(cur.displayText || getText(cur)));
+      elt.hintId = i;
+    }
+
+    var container = completion.options.container || ownerDocument.body;
+    var pos = cm.cursorCoords(completion.options.alignWithWord ? data.from : null);
+    var left = pos.left, top = pos.bottom, below = true;
+    var offsetLeft = 0, offsetTop = 0;
+    if (container !== ownerDocument.body) {
+      // We offset the cursor position because left and top are relative to the offsetParent's top left corner.
+      var isContainerPositioned = ['absolute', 'relative', 'fixed'].indexOf(parentWindow.getComputedStyle(container).position) !== -1;
+      var offsetParent = isContainerPositioned ? container : container.offsetParent;
+      var offsetParentPosition = offsetParent.getBoundingClientRect();
+      var bodyPosition = ownerDocument.body.getBoundingClientRect();
+      offsetLeft = (offsetParentPosition.left - bodyPosition.left - offsetParent.scrollLeft);
+      offsetTop = (offsetParentPosition.top - bodyPosition.top - offsetParent.scrollTop);
+    }
+    hints.style.left = (left - offsetLeft) + "px";
+    hints.style.top = (top - offsetTop) + "px";
+
+    // If we're at the edge of the screen, then we want the menu to appear on the left of the cursor.
+    var winW = parentWindow.innerWidth || Math.max(ownerDocument.body.offsetWidth, ownerDocument.documentElement.offsetWidth);
+    var winH = parentWindow.innerHeight || Math.max(ownerDocument.body.offsetHeight, ownerDocument.documentElement.offsetHeight);
+    container.appendChild(hints);
+    var box = hints.getBoundingClientRect(), overlapY = box.bottom - winH;
+    var scrolls = hints.scrollHeight > hints.clientHeight + 1
+    var startScroll = cm.getScrollInfo();
+
+    if (overlapY > 0) {
+      var height = box.bottom - box.top, curTop = pos.top - (pos.bottom - box.top);
+      if (curTop - height > 0) { // Fits above cursor
+        hints.style.top = (top = pos.top - height - offsetTop) + "px";
+        below = false;
+      } else if (height > winH) {
+        hints.style.height = (winH - 5) + "px";
+        hints.style.top = (top = pos.bottom - box.top - offsetTop) + "px";
+        var cursor = cm.getCursor();
+        if (data.from.ch != cursor.ch) {
+          pos = cm.cursorCoords(cursor);
+          hints.style.left = (left = pos.left - offsetLeft) + "px";
+          box = hints.getBoundingClientRect();
+        }
+      }
+    }
+    var overlapX = box.right - winW;
+    if (overlapX > 0) {
+      if (box.right - box.left > winW) {
+        hints.style.width = (winW - 5) + "px";
+        overlapX -= (box.right - box.left) - winW;
+      }
+      hints.style.left = (left = pos.left - overlapX - offsetLeft) + "px";
+    }
+    if (scrolls) for (var node = hints.firstChild; node; node = node.nextSibling)
+      node.style.paddingRight = cm.display.nativeBarWidth + "px"
+
+    cm.addKeyMap(this.keyMap = buildKeyMap(completion, {
+      moveFocus: function(n, avoidWrap) { widget.changeActive(widget.selectedHint + n, avoidWrap); },
+      setFocus: function(n) { widget.changeActive(n); },
+      menuSize: function() { return widget.screenAmount(); },
+      length: completions.length,
+      close: function() { completion.close(); },
+      pick: function() { widget.pick(); },
+      data: data
+    }));
+
+    if (completion.options.closeOnUnfocus) {
+      var closingOnBlur;
+      cm.on("blur", this.onBlur = function() { closingOnBlur = setTimeout(function() { completion.close(); }, 100); });
+      cm.on("focus", this.onFocus = function() { clearTimeout(closingOnBlur); });
+    }
+
+    cm.on("scroll", this.onScroll = function() {
+      var curScroll = cm.getScrollInfo(), editor = cm.getWrapperElement().getBoundingClientRect();
+      var newTop = top + startScroll.top - curScroll.top;
+      var point = newTop - (parentWindow.pageYOffset || (ownerDocument.documentElement || ownerDocument.body).scrollTop);
+      if (!below) point += hints.offsetHeight;
+      if (point <= editor.top || point >= editor.bottom) return completion.close();
+      hints.style.top = newTop + "px";
+      hints.style.left = (left + startScroll.left - curScroll.left) + "px";
+    });
+
+    CodeMirror.on(hints, "dblclick", function(e) {
+      var t = getHintElement(hints, e.target || e.srcElement);
+      if (t && t.hintId != null) {widget.changeActive(t.hintId); widget.pick();}
+    });
+
+    CodeMirror.on(hints, "click", function(e) {
+      var t = getHintElement(hints, e.target || e.srcElement);
+      if (t && t.hintId != null) {
+        widget.changeActive(t.hintId);
+        if (completion.options.completeOnSingleClick) widget.pick();
+      }
+    });
+
+    CodeMirror.on(hints, "mousedown", function() {
+      setTimeout(function(){cm.focus();}, 20);
+    });
+
+    CodeMirror.signal(data, "select", completions[this.selectedHint], hints.childNodes[this.selectedHint]);
+    return true;
+  }
+
+  Widget.prototype = {
+    close: function() {
+      if (this.completion.widget != this) return;
+      this.completion.widget = null;
+      this.hints.parentNode.removeChild(this.hints);
+      this.completion.cm.removeKeyMap(this.keyMap);
+
+      var cm = this.completion.cm;
+      if (this.completion.options.closeOnUnfocus) {
+        cm.off("blur", this.onBlur);
+        cm.off("focus", this.onFocus);
+      }
+      cm.off("scroll", this.onScroll);
+    },
+
+    disable: function() {
+      this.completion.cm.removeKeyMap(this.keyMap);
+      var widget = this;
+      this.keyMap = {Enter: function() { widget.picked = true; }};
+      this.completion.cm.addKeyMap(this.keyMap);
+    },
+
+    pick: function() {
+      this.completion.pick(this.data, this.selectedHint);
+    },
+
+    changeActive: function(i, avoidWrap) {
+      if (i >= this.data.list.length)
+        i = avoidWrap ? this.data.list.length - 1 : 0;
+      else if (i < 0)
+        i = avoidWrap ? 0  : this.data.list.length - 1;
+      if (this.selectedHint == i) return;
+      var node = this.hints.childNodes[this.selectedHint];
+      if (node) node.className = node.className.replace(" " + ACTIVE_HINT_ELEMENT_CLASS, "");
+      node = this.hints.childNodes[this.selectedHint = i];
+      node.className += " " + ACTIVE_HINT_ELEMENT_CLASS;
+      if (node.offsetTop < this.hints.scrollTop)
+        this.hints.scrollTop = node.offsetTop - 3;
+      else if (node.offsetTop + node.offsetHeight > this.hints.scrollTop + this.hints.clientHeight)
+        this.hints.scrollTop = node.offsetTop + node.offsetHeight - this.hints.clientHeight + 3;
+      CodeMirror.signal(this.data, "select", this.data.list[this.selectedHint], node);
+    },
+
+    screenAmount: function() {
+      return Math.floor(this.hints.clientHeight / this.hints.firstChild.offsetHeight) || 1;
+    }
+  };
+
+  function applicableHelpers(cm, helpers) {
+    if (!cm.somethingSelected()) return helpers
+    var result = []
+    for (var i = 0; i < helpers.length; i++)
+      if (helpers[i].supportsSelection) result.push(helpers[i])
+    return result
+  }
+
+  function fetchHints(hint, cm, options, callback) {
+    if (hint.async) {
+      hint(cm, callback, options)
+    } else {
+      var result = hint(cm, options)
+      if (result && result.then) result.then(callback)
+      else callback(result)
+    }
+  }
+
+  function resolveAutoHints(cm, pos) {
+    var helpers = cm.getHelpers(pos, "hint"), words
+    if (helpers.length) {
+      var resolved = function(cm, callback, options) {
+        var app = applicableHelpers(cm, helpers);
+        function run(i) {
+          if (i == app.length) return callback(null)
+          fetchHints(app[i], cm, options, function(result) {
+            if (result && result.list.length > 0) callback(result)
+            else run(i + 1)
+          })
+        }
+        run(0)
+      }
+      resolved.async = true
+      resolved.supportsSelection = true
+      return resolved
+    } else if (words = cm.getHelper(cm.getCursor(), "hintWords")) {
+      return function(cm) { return CodeMirror.hint.fromList(cm, {words: words}) }
+    } else if (CodeMirror.hint.anyword) {
+      return function(cm, options) { return CodeMirror.hint.anyword(cm, options) }
+    } else {
+      return function() {}
+    }
+  }
+
+  CodeMirror.registerHelper("hint", "auto", {
+    resolve: resolveAutoHints
+  });
+
+  CodeMirror.registerHelper("hint", "fromList", function(cm, options) {
+    var cur = cm.getCursor(), token = cm.getTokenAt(cur)
+    var term, from = CodeMirror.Pos(cur.line, token.start), to = cur
+    if (token.start < cur.ch && /\w/.test(token.string.charAt(cur.ch - token.start - 1))) {
+      term = token.string.substr(0, cur.ch - token.start)
+    } else {
+      term = ""
+      from = cur
+    }
+    var found = [];
+    for (var i = 0; i < options.words.length; i++) {
+      var word = options.words[i];
+      if (word.slice(0, term.length) == term)
+        found.push(word);
+    }
+
+    if (found.length) return {list: found, from: from, to: to};
+  });
+
+  CodeMirror.commands.autocomplete = CodeMirror.showHint;
+
+  var defaultOptions = {
+    hint: CodeMirror.hint.auto,
+    completeSingle: true,
+    alignWithWord: true,
+    closeCharacters: /[\s()\[\]{};:>,]/,
+    closeOnUnfocus: true,
+    completeOnSingleClick: true,
+    container: null,
+    customKeys: null,
+    extraKeys: null
+  };
+
+  CodeMirror.defineOption("hintOptions", null);
+});