diff --git a/style.css b/style.css
new file mode 100644
index 0000000..c95aee5
--- /dev/null
+++ b/style.css
@@ -0,0 +1,22 @@
+* { box-sizing: border-box; }
+h1, h2, h3 { margin-bottom: 0.5rem; }
+h2 { border-bottom: 1px solid gray; margin-bottom: 0.5rem; }
+hr { border: none; border-top: 1px solid gray; }
+
+.alert { margin-left: 0; padding-left: 1rem; border-left: 3px solid black; }
+.alert.success { border-color: lime; }
+.alert.info { border-color: blue; }
+.alert.warning { border-color: gold; }
+.alert.danger { border-color: red; }
+.btn.danger, span.danger { color: red; }
+.btn.warning, span.warning { color: gold; }
+.unstyled-list { list-style: none; padding-left: 0; }
+.inline-list { list-style: none; margin-top: 0; }
+.inline-list li { display: inline-block; }
+.grid-wrapper { display: grid; grid-template-columns: repeat(auto-fill, 120px); }
+.d-flex { display: -webkit-flex; display: -moz-flex; display: flex; }
+.flex-fill { -webkit-flex: 1 1 auto; -moz-flex: 1 1 auto; flex: 1 1 auto; }
+
+@media screen and (min-width: 780px) {
+	body { max-width: 768px; margin: 0 auto; }
+}