diff --git a/.CI/Jenkinsfile b/.CI/Jenkinsfile
index 3a27007ca..6d34d8285 100644
--- a/.CI/Jenkinsfile
+++ b/.CI/Jenkinsfile
@@ -31,6 +31,7 @@ pipeline {
       sh 'latexmk -pdf MLS.tex'
       sh 'latexml MLS.tex --includestyles --path=media --dest MLS.xml'
       sh 'latexmlpost MLS.xml -format html -pmml --splitat=chapter --splitnaming=labelrelative --javascript=LaTeXML-maybeMathjax.js --navigationtoc=context --css=css/MLS.css --css=css/MLS-navbar-left.css --dest MLS.html'
+      sh '.scripts/patch-viewport.sh'
       sh 'ln -s preface.html Chx1.html'
       sh 'ln -s lexical-structure.html Ch2.html'
       sh 'ln -s operators-and-expressions.html Ch3.html'
diff --git a/.scripts/patch-viewport.sh b/.scripts/patch-viewport.sh
new file mode 100755
index 000000000..1f25a7afa
--- /dev/null
+++ b/.scripts/patch-viewport.sh
@@ -0,0 +1,5 @@
+#!/bin/sh -xe
+
+sed -i.bak 's;</head>;<meta name="viewport" content="width=device-width, initial-scale=1">\
+</head>;' *.html
+rm *.html.bak # MacOS sed does not support -i without extension
diff --git a/Makefile b/Makefile
index 495801f1c..9244fd77b 100644
--- a/Makefile
+++ b/Makefile
@@ -25,3 +25,4 @@ MLS.pdf: *.tex chapters/*.tex
 MLS.html: MLS.tex chapters/*.tex
 	$(LATEXMLPREFIX)latexml MLS.tex --includestyles --path=media --dest MLS.xml
 	$(LATEXMLPREFIX)latexmlpost MLS.xml -format html -pmml --splitat=chapter --splitnaming=labelrelative --javascript=LaTeXML-maybeMathjax.js --navigationtoc=context --css=css/MLS.css --css=css/MLS-navbar-left.css --dest $@
+	./scripts/patch-viewport.sh