diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6c7e31b..fa5858f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -3,12 +3,12 @@ name: CI
 on:
   push:
     branches:
-    - master
+      - master
   pull_request:
     types:
-    - opened
-    - synchronize
-    - reopened
+      - opened
+      - synchronize
+      - reopened
 
 jobs:
   ubuntu:
@@ -19,107 +19,107 @@ jobs:
       fail-fast: false
       matrix:
         os:
-        - ubuntu-latest
+          - ubuntu-latest
         ruby:
-        - "3.3"
-        - "3.2"
-        - "3.1"
-        - "3.0"
-        - "2.7"
-        - "2.6"
-        - "2.5"
-        - debug
+          - "3.3"
+          - "3.2"
+          - "3.1"
+          - "3.0"
+          - "2.7"
+          - "2.6"
+          - "2.5"
+          - debug
 
     steps:
-    - uses: actions/checkout@v3
-      with:
-        fetch-depth: 1
-
-    - uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: ${{ matrix.ruby }}
-
-    - run: rake build
-
-    - name: Install irb for old Ruby
-      if: |
-        matrix.ruby == '2.5' ||
-        matrix.ruby == '2.4' ||
-        matrix.ruby == '2.3'
-      run: |
-        cat <<GEMFILE > Gemfile.irb
-        source 'https://rubygems.org'
-        gem 'irb'
-        GEMFILE
-        BUNDLE_GEMFILE=Gemfile.irb bundle install --jobs 4 --retry 3
-
-    - run: gem install pkg/*.gem
-
-    - run: ruby -r iruby -e "p IRuby::SessionAdapter.select_adapter_class"
-      env:
-        IRUBY_SESSION_ADAPTER: ffi-rzmq
-
-    - name: Install requirements on ubuntu
-      run: |
-        sudo apt update
-        sudo apt install -y --no-install-recommends \
-                 libczmq-dev \
-                 python3 \
-                 python3-pip \
-                 python3-setuptools
-        sudo pip3 install wheel
-        sudo pip3 install -r ci/requirements.txt
-
-    - run: bundle install --jobs 4 --retry 3
-
-    - name: Run tests
-      env:
-        PYTHON: python3
-        ADAPTERS: cztop ffi-rzmq
-      run: |
-        for adapter in $ADAPTERS; do
-          export IRUBY_TEST_SESSION_ADAPTER_NAME=$adapter
-          bundle exec rake test TESTOPTS="-v"
-        done
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 1
+
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+
+      - run: rake build
+
+      - name: Install irb for old Ruby
+        if: |
+          matrix.ruby == '2.5' ||
+          matrix.ruby == '2.4' ||
+          matrix.ruby == '2.3'
+        run: |
+          cat <<GEMFILE > Gemfile.irb
+          source 'https://rubygems.org'
+          gem 'irb'
+          GEMFILE
+          BUNDLE_GEMFILE=Gemfile.irb bundle install --jobs 4 --retry 3
+
+      - run: gem install pkg/*.gem
+
+      - run: ruby -r iruby -e "p IRuby::SessionAdapter.select_adapter_class"
+        env:
+          IRUBY_SESSION_ADAPTER: ffi-rzmq
+
+      - name: Install requirements on ubuntu
+        run: |
+          sudo apt update
+          sudo apt install -y --no-install-recommends \
+                   libczmq-dev \
+                   python3 \
+                   python3-pip \
+                   python3-setuptools
+          sudo pip3 install wheel
+          sudo pip3 install -r ci/requirements.txt
+
+      - run: bundle install --jobs 4 --retry 3
+
+      - name: Run tests
+        env:
+          PYTHON: python3
+          ADAPTERS: cztop ffi-rzmq
+        run: |
+          for adapter in $ADAPTERS; do
+            export IRUBY_TEST_SESSION_ADAPTER_NAME=$adapter
+            bundle exec rake test TESTOPTS="-v"
+          done
 
   windows:
     name: Windows
     runs-on: windows-latest
 
     steps:
-    - uses: actions/checkout@v3
-      with:
-        fetch-depth: 1
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 1
 
-    - uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: "3.0"
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: "3.0"
 
-    - run: rake build
+      - run: rake build
 
-    - run: gem install pkg/*.gem
+      - run: gem install pkg/*.gem
 
-    - run: ruby -r iruby -e "p IRuby::SessionAdapter.select_adapter_class"
-      env:
-        IRUBY_SESSION_ADAPTER: ffi-rzmq
+      - run: ruby -r iruby -e "p IRuby::SessionAdapter.select_adapter_class"
+        env:
+          IRUBY_SESSION_ADAPTER: ffi-rzmq
 
   macos:
     name: macOS
     runs-on: macos-latest
 
     steps:
-    - uses: actions/checkout@v3
-      with:
-        fetch-depth: 1
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 1
 
-    - uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: "3.0"
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: "3.0"
 
-    - run: rake build
+      - run: rake build
 
-    - run: gem install pkg/*.gem
+      - run: gem install pkg/*.gem
 
-    - run: ruby -r iruby -e "p IRuby::SessionAdapter.select_adapter_class"
-      env:
-        IRUBY_SESSION_ADAPTER: ffi-rzmq
+      - run: ruby -r iruby -e "p IRuby::SessionAdapter.select_adapter_class"
+        env:
+          IRUBY_SESSION_ADAPTER: ffi-rzmq
diff --git a/README.md b/README.md
index 9052d4b..1e3faa2 100644
--- a/README.md
+++ b/README.md
@@ -10,11 +10,11 @@ IRuby is a Ruby kernel for [Jupyter project](http://try.jupyter.org/).
 
 You can try IRuby with a sample notebook on Binder (the same link as the banner placed above):
 
-https://mybinder.org/v2/gh/RubyData/binder/master?filepath=ruby-data.ipynb
+<https://mybinder.org/v2/gh/RubyData/binder/master?filepath=ruby-data.ipynb>
 
 The following URL launches JupyterLab directly on Binder.
 
-https://mybinder.org/v2/gh/RubyData/binder/master?filepath=../lab
+<https://mybinder.org/v2/gh/RubyData/binder/master?filepath=../lab>
 
 ## Installation
 
@@ -31,13 +31,12 @@ The following dependencies are optional.
 
 * [Pry][Pry], if you want to use [Pry][Pry] instead of IRB for the code execution backend
 
-
 ### Installing Jupyter Notebook and/or JupyterLab
 
 See the official document to know how to install Jupyter Notebook and/or JupyterLab.
 
-* https://jupyter.readthedocs.io/en/latest/install/notebook-classic.html
-* https://jupyter.readthedocs.io/en/latest/install.html
+* <https://jupyter.readthedocs.io/en/latest/install/notebook-classic.html>
+* <https://jupyter.readthedocs.io/en/latest/install.html>
 
 ### Ubuntu
 
@@ -106,7 +105,7 @@ iruby register --force
 
 ### Docker
 
-Try [RubyData Docker Stacks](https://github.com/RubyData/docker-stacks). 
+Try [RubyData Docker Stacks](https://github.com/RubyData/docker-stacks).
 Running jupyter notebook:
 
 ```shell
@@ -123,7 +122,7 @@ You can use Java classes in your IRuby notebook.
 After installation, make sure that your `env` is set up to use jruby.
 
 ```shell
-$ env ruby -v
+env ruby -v
 ```
 
 If you use RVM, it is enough to switch the current version to jruby.
@@ -131,7 +130,7 @@ If you use RVM, it is enough to switch the current version to jruby.
 If you have already used IRuby with a different version, you need to generate a new kernel:
 
 ```shell
-$ iruby register --force
+iruby register --force
 ```
 
 ### Install the development version of IRuby
@@ -182,7 +181,7 @@ Contributions to IRuby are very welcome.
 
 To former contributors
 
-In February 2021, [IRuby became the canonical repository](https://github.com/SciRuby/iruby/issues/285) and is no longer a fork from [minrk/iruby](https://github.com/minrk/iruby). Please fork from this repository again before making pull requests. 
+In February 2021, [IRuby became the canonical repository](https://github.com/SciRuby/iruby/issues/285) and is no longer a fork from [minrk/iruby](https://github.com/minrk/iruby). Please fork from this repository again before making pull requests.
 
 ## License