diff --git a/.ruby-version b/.ruby-version
new file mode 100644
index 0000000..0bee604
--- /dev/null
+++ b/.ruby-version
@@ -0,0 +1 @@
+2.3.3
diff --git a/Gemfile b/Gemfile
index 0e9d7ef..74e62de 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,6 +2,8 @@
 # the following line to use "http://" instead
 source 'https://rubygems.org'
 
+ruby "2.3.3"
+
 gem "bourbon"
 
 gem "middleman"
diff --git a/Gemfile.lock b/Gemfile.lock
index 0a48a37..a6d14f5 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -9,7 +9,7 @@ GEM
     addressable (2.5.0)
       public_suffix (~> 2.0, >= 2.0.2)
     backports (3.6.8)
-    bourbon (4.2.7)
+    bourbon (4.3.0)
       sass (~> 3.4)
       thor (~> 0.19)
     coffee-script (2.4.1)
@@ -20,12 +20,12 @@ GEM
       sass (>= 3.2, < 3.5)
     concurrent-ruby (1.0.4)
     contracts (0.13.0)
-    dotenv (2.1.1)
+    dotenv (2.2.0)
     em-websocket (0.5.1)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
     erubis (2.7.0)
-    eventmachine (1.2.1)
+    eventmachine (1.2.2)
     execjs (2.7.0)
     fast_blank (1.0.0)
     fastimage (2.0.1)
@@ -35,7 +35,7 @@ GEM
       tilt
     hamster (3.0.0)
       concurrent-ruby (~> 1.0)
-    hashie (3.4.6)
+    hashie (3.5.1)
     http_parser.rb (0.6.0)
     i18n (0.7.0)
     kramdown (1.13.2)
@@ -46,17 +46,17 @@ GEM
     mgd (0.2.0)
       middleman (>= 3.0.0)
       trollop (= 2.1.2)
-    middleman (4.2.0)
+    middleman (4.2.1)
       coffee-script (~> 2.2)
       compass-import-once (= 1.0.5)
       haml (>= 4.0.5)
       kramdown (~> 1.2)
-      middleman-cli (= 4.2.0)
-      middleman-core (= 4.2.0)
+      middleman-cli (= 4.2.1)
+      middleman-core (= 4.2.1)
       sass (>= 3.4.0, < 4.0)
-    middleman-cli (4.2.0)
+    middleman-cli (4.2.1)
       thor (>= 0.17.0, < 2.0)
-    middleman-core (4.2.0)
+    middleman-core (4.2.1)
       activesupport (>= 4.2, < 5.1)
       addressable (~> 2.3)
       backports (~> 3.6)
@@ -96,13 +96,13 @@ GEM
     rack-livereload (0.3.16)
       rack
     rb-fsevent (0.9.8)
-    rb-inotify (0.9.7)
+    rb-inotify (0.9.8)
       ffi (>= 0.5.0)
     sass (3.4.23)
     servolux (0.12.0)
     thor (0.19.4)
     thread_safe (0.3.5)
-    tilt (2.0.5)
+    tilt (2.0.6)
     trollop (2.1.2)
     tzinfo (1.2.2)
       thread_safe (~> 0.1)
@@ -120,5 +120,8 @@ DEPENDENCIES
   tzinfo-data
   wdm (~> 0.1.0)
 
+RUBY VERSION
+   ruby 2.3.3p222
+
 BUNDLED WITH
-   1.13.6
+   1.14.3