diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
index 8b4a56e..e2928c0 100644
--- a/.github/workflows/deploy.yml
+++ b/.github/workflows/deploy.yml
@@ -7,7 +7,7 @@ on:
 
 jobs:
   deploy:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
       - name: Setup mdBook
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..485dee6
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.idea