Print CSS to fix printing problems

No more sidebar filling half of the printed pages, or unnecessary blank pages.

static/css/print.css

@@ -0,0 +1,19 @@
+.sidebar {
+  display: none !important;
+}
+
+.content {
+  margin: 0 auto;
+  width: 100%;
+  float: none;
+  display: initial;
+}
+
+.container {
+  width: 100%;
+  float: none;
+  display: initial;
+  padding-left:  1rem;
+  padding-right: 1rem;
+  margin: 0 auto;
+}