diff --git a/.github/semantic.yml b/.github/semantic.yml
new file mode 100644
index 000000000..e7f5bb59b
--- /dev/null
+++ b/.github/semantic.yml
@@ -0,0 +1,4 @@
+titleAndCommits: true
+allowMergeCommits: true
+allowRevertCommits: true
+anyCommit: true
diff --git a/build/build.js b/build/build.js
index 6fa2b123b..99e2f0c4a 100644
--- a/build/build.js
+++ b/build/build.js
@@ -59,6 +59,7 @@ const buildAllPlugin = function () {
     {name: 'emoji', input: 'emoji.js'},
     {name: 'external-script', input: 'external-script.js'},
     {name: 'front-matter', input: 'front-matter/index.js'},
+    {name: 'sideplus', input: 'sideplus/index.js'},
     {name: 'zoom-image', input: 'zoom-image.js'},
     {name: 'disqus', input: 'disqus.js'},
     {name: 'gitalk', input: 'gitalk.js'}
diff --git a/docs/plugins.md b/docs/plugins.md
index 2eb47ce57..15de43aa9 100644
--- a/docs/plugins.md
+++ b/docs/plugins.md
@@ -192,6 +192,21 @@ A docsify.js plugin for displaying tabbed content from markdown.
 
 Provided by [@jhildenbiddle](https://github.com/jhildenbiddle/docsify-tabs).
 
+## sideplus
+
+Using this plugin, you can expand/collapse sidebar items by click the arrow icon.
+
+```
+  <script>
+    window.$docsify = {
+      loadSidebar: true,
+      maxLevel: 6,
+      subMaxLevel: 6,
+    }
+  </script>
+  <script src="lib/plugins/sideplus.js"></script>
+```
+
 ## More plugins
 
 See [awesome-docsify](awesome?id=plugins)
diff --git a/src/core/event/scroll.js b/src/core/event/scroll.js
index 946589996..e39335722 100644
--- a/src/core/event/scroll.js
+++ b/src/core/event/scroll.js
@@ -1,21 +1,26 @@
-import Tweezer from 'tweezer.js';
 import { isMobile } from '../util/env';
 import * as dom from '../util/dom';
 import { removeParams } from '../router/util';
 import config from '../config';
+import Tweezer from 'tweezer.js';
 
 const nav = {};
 let hoverOver = false;
 let scroller = null;
-let enableScrollEvent = true;
 let coverHeight = 0;
 
+const scrollEvent = {
+  plugin: false,
+  enable: true,
+};
+export { scrollEvent };
+
 function scrollTo(el, offset = 0) {
   if (scroller) {
     scroller.stop();
   }
 
-  enableScrollEvent = false;
+  scrollEvent.enable = false;
   scroller = new Tweezer({
     start: window.pageYOffset,
     end: el.getBoundingClientRect().top + window.pageYOffset - offset,
@@ -23,20 +28,19 @@ function scrollTo(el, offset = 0) {
   })
     .on('tick', v => window.scrollTo(0, v))
     .on('done', () => {
-      enableScrollEvent = true;
+      scrollEvent.enable = true;
       scroller = null;
     })
     .begin();
 }
 
 function highlight(path) {
-  if (!enableScrollEvent) {
+  if (!scrollEvent.enable) {
     return;
   }
 
   const sidebar = dom.getNode('.sidebar');
   const anchors = dom.findAll('.anchor');
-  const wrap = dom.find(sidebar, '.sidebar-nav');
   let active = dom.find(sidebar, 'li.active');
   const doc = document.documentElement;
   const top = ((doc && doc.scrollTop) || document.body.scrollTop) - coverHeight;
@@ -70,12 +74,20 @@ function highlight(path) {
   li.classList.add('active');
   active = li;
 
+  if (!scrollEvent.plugin) {
+    scrollSidebarIntoView(active);
+  }
+}
+
+export function scrollSidebarIntoView(active) {
+  const sidebar = dom.getNode('.sidebar');
+  const wrap = dom.find(sidebar, '.sidebar-nav');
   // Scroll into view
   // https://github.com/vuejs/vuejs.org/blob/master/themes/vue/source/js/common.js#L282-L297
   if (!hoverOver && dom.body.classList.contains('sticky')) {
     const height = sidebar.clientHeight;
     const curOffset = 0;
-    const cur = active.offsetTop + active.clientHeight + 40;
+    const cur = active.offsetTop + active.clientHeight + height / 2;
     const isInView =
       active.offsetTop >= wrap.scrollTop && cur <= wrap.scrollTop + height;
     const notThan = cur - curOffset < height;
diff --git a/src/core/render/compiler.js b/src/core/render/compiler.js
index 4eaf51215..0638c321a 100644
--- a/src/core/render/compiler.js
+++ b/src/core/render/compiler.js
@@ -1,4 +1,3 @@
-import marked from 'marked';
 import { isAbsolutePath, getPath, getParentPath } from '../router/util';
 import { isFn, merge, cached, isPrimitive } from '../util/core';
 import { tree as treeTpl } from './tpl';
@@ -12,6 +11,7 @@ import { paragraphCompiler } from './compiler/paragraph';
 import { taskListCompiler } from './compiler/taskList';
 import { taskListItemCompiler } from './compiler/taskListItem';
 import { linkCompiler } from './compiler/link';
+import marked from 'marked';
 
 const cachedLinks = {};
 
@@ -278,7 +278,7 @@ export class Compiler {
       }
 
       const tree = this.cacheTree[currentPath] || genTree(toc, level);
-      html = treeTpl(tree, '<ul>{inner}</ul>');
+      html = treeTpl(tree);
       this.cacheTree[currentPath] = tree;
     }
 
diff --git a/src/core/render/tpl.js b/src/core/render/tpl.js
index 85efa436c..c672e010c 100644
--- a/src/core/render/tpl.js
+++ b/src/core/render/tpl.js
@@ -93,10 +93,12 @@ export function tree(toc, tpl = '<ul class="app-sub-sidebar">{inner}</ul>') {
 
   let innerHTML = '';
   toc.forEach(node => {
-    innerHTML += `<li><a class="section-link" href="${node.slug}">${node.title}</a></li>`;
+    innerHTML += `<li>`;
+    innerHTML += `<a class="section-link" href="${node.slug}">${node.title}</a>`;
     if (node.children) {
       innerHTML += tree(node.children, tpl);
     }
+    innerHTML += `</li>`;
   });
   return tpl.replace('{inner}', innerHTML);
 }
diff --git a/src/plugins/sideplus/index.js b/src/plugins/sideplus/index.js
new file mode 100644
index 000000000..436ac720b
--- /dev/null
+++ b/src/plugins/sideplus/index.js
@@ -0,0 +1,19 @@
+/* eslint-disable no-unused-vars */
+/* eslint-disable no-console */
+import { style } from './style';
+import { rebuild, collapse } from './sidebar';
+import { highlight } from './scroll';
+
+const install = function(hook, vm) {
+  hook.doneEach(function() {
+    rebuild();
+    highlight();
+  });
+
+  hook.mounted(function() {
+    style();
+    collapse();
+  });
+};
+
+$docsify.plugins = [].concat(install, $docsify.plugins);
diff --git a/src/plugins/sideplus/scroll.js b/src/plugins/sideplus/scroll.js
new file mode 100644
index 000000000..9d5322c37
--- /dev/null
+++ b/src/plugins/sideplus/scroll.js
@@ -0,0 +1,51 @@
+import { scrollSidebarIntoView, scrollEvent } from '../../core/event/scroll';
+
+export function highlight() {
+  const dom = Docsify.dom;
+  scrollEvent.plugin = true;
+
+  dom.off('scroll', () => highlightParent());
+  dom.on('scroll', () => highlightParent());
+}
+
+function highlightParent() {
+  if (!scrollEvent.enable) {
+    return;
+  }
+
+  const dom = Docsify.dom;
+
+  const sidebar = dom.getNode('.sidebar');
+  let active = dom.find(sidebar, 'li.active');
+  let parents = dom.findAll(sidebar, 'li.parent');
+
+  parents.forEach(node => node.classList.remove('parent'));
+  active = findParents(active);
+
+  scrollSidebarIntoView(active);
+}
+
+function findParents(active) {
+  if (!active) {
+    return active;
+  }
+
+  let top = active;
+  let node = active.parentNode;
+
+  while (node) {
+    if (node.classList.contains('app-sub-sidebar')) {
+      node = node.parentNode;
+      continue;
+    } else if (node.classList.contains('has-children')) {
+      node.classList.add('parent');
+      if (node.classList.contains('collapse')) {
+        top = node;
+      }
+      node = node.parentNode;
+      continue;
+    } else {
+      return top;
+    }
+  }
+}
diff --git a/src/plugins/sideplus/sidebar.js b/src/plugins/sideplus/sidebar.js
new file mode 100644
index 000000000..1cccf03e2
--- /dev/null
+++ b/src/plugins/sideplus/sidebar.js
@@ -0,0 +1,41 @@
+export function rebuild() {
+  const dom = Docsify.dom;
+
+  const sidebar = dom.getNode('.sidebar');
+  if (sidebar === null || sidebar === undefined) {
+    return;
+  }
+
+  const list = dom.findAll(sidebar, '.app-sub-sidebar li');
+
+  list.forEach(node => {
+    node.prepend(document.createElement('span'));
+    if (
+      node.lastChild &&
+      node.lastChild.classList &&
+      node.lastChild.classList.contains('app-sub-sidebar')
+    ) {
+      node.classList.add('has-children');
+    }
+  });
+}
+
+export function collapse() {
+  const dom = Docsify.dom;
+
+  const sidebar = dom.getNode('.sidebar');
+  if (sidebar === null || sidebar === undefined) {
+    return;
+  }
+
+  dom.on(sidebar, 'click', ({ target }) => {
+    if (
+      target.nodeName === 'SPAN' &&
+      target.nextSibling &&
+      target.nextSibling.classList &&
+      target.nextSibling.classList.contains('section-link')
+    ) {
+      dom.toggleClass(target.parentNode, 'collapse');
+    }
+  });
+}
diff --git a/src/plugins/sideplus/style.js b/src/plugins/sideplus/style.js
new file mode 100644
index 000000000..128107b16
--- /dev/null
+++ b/src/plugins/sideplus/style.js
@@ -0,0 +1,41 @@
+export function style() {
+  const code = `
+  .app-sub-sidebar li:before {
+    content: '';
+    padding: 0;
+  }
+  .app-sub-sidebar li > span:after {
+    content: '\\00A0';
+    font-size: 12px;
+    line-height: 1em;
+    padding: 0 12px 0 0;
+    float: left;
+  }
+  .app-sub-sidebar li.has-children > span:after {
+    -webkit-writing-mode: vertical-lr;
+        -ms-writing-mode: tb-lr;
+            writing-mode: vertical-lr;
+    content: '\\276F';
+    font-size: 12px;
+    line-height: 1em;
+    padding: 12px 3px 0 0;
+    float: left;
+  }
+  .app-sub-sidebar li.has-children.collapse > span:after {
+    -webkit-writing-mode: horizontal-tb;
+        -ms-writing-mode: lr-tb;
+            writing-mode: horizontal-tb;
+    content: '\\276F';
+    font-size: 12px;
+    line-height: 1em;
+    padding: 9px 7px 0 2px;
+    float: left;
+  }
+  .sidebar li.collapse.parent > a {
+    border-right: 2px solid;
+    color: var(--theme-color, #42b983);
+    font-weight: 600;
+  }`;
+
+  Docsify.dom.style(code);
+}