diff --git a/Gemfile b/Gemfile
index 9303bac..4003535 100644
--- a/Gemfile
+++ b/Gemfile
@@ -69,7 +69,7 @@ end
 gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
 
 gem 'annotate'
-gem 'bootstrap', '~> 4.0.0.alpha6'
+gem 'bootstrap', '~> 4.3.1'
 
 # for image attachments
 gem 'paperclip', '~> 5.0.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 6588fec..2a9ec43 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -44,15 +44,15 @@ GEM
       activerecord (>= 3.2, < 7.0)
       rake (>= 10.4, < 13.0)
     arel (7.1.4)
-    autoprefixer-rails (9.6.1.1)
+    autoprefixer-rails (9.7.0)
       execjs
     backports (3.15.0)
     bcrypt (3.1.13)
     bindex (0.8.1)
-    bootstrap (4.0.0)
-      autoprefixer-rails (>= 6.0.3)
-      popper_js (>= 1.12.9, < 2)
-      sass (>= 3.5.2)
+    bootstrap (4.3.1)
+      autoprefixer-rails (>= 9.1.0)
+      popper_js (>= 1.14.3, < 2)
+      sassc-rails (>= 2.0.0)
     builder (3.2.3)
     byebug (11.0.1)
     cancancan (2.3.0)
@@ -230,6 +230,16 @@ GEM
       sprockets (>= 2.8, < 4.0)
       sprockets-rails (>= 2.0, < 4.0)
       tilt (>= 1.1, < 3)
+    sassc (2.2.1)
+      ffi (~> 1.9)
+    sassc (2.2.1-x64-mingw32)
+      ffi (~> 1.9)
+    sassc-rails (2.1.2)
+      railties (>= 4.0.0)
+      sassc (>= 2.0)
+      sprockets (> 3.0)
+      sprockets-rails
+      tilt
     sexp_processor (4.12.1)
     spring (2.1.0)
     spring-watcher-listen (2.0.1)
@@ -273,7 +283,7 @@ PLATFORMS
 DEPENDENCIES
   annotate
   bcrypt (~> 3.1.11)
-  bootstrap (~> 4.0.0.alpha6)
+  bootstrap (~> 4.3.1)
   byebug
   cancancan (~> 2.0)
   coffee-rails (~> 4.2)