ts: Convert css_variables.js to TypeScript.

tools/test-js-with-node

@@ -73,7 +73,7 @@ EXEMPT_FILES = make_set(
         "web/src/confirm_dialog.js",
         "web/src/copy_and_paste.js",
         "web/src/csrf.ts",
-        "web/src/css_variables.js",
+        "web/src/css_variables.ts",
         "web/src/dark_theme.js",
         "web/src/debug.js",
         "web/src/deprecated_feature_notice.js",

web/src/css_variables.js

@@ -1,39 +0,0 @@
-/* eslint-env commonjs */
-
-"use strict";
-
-// Media query breakpoints according to Bootstrap 4.5
-const xs = 0;
-const sm = 576;
-const md = 768;
-const lg = 992;
-const xl = 1200;
-
-// Breakpoints for mobile devices used by Google Chrome as of Version 86
-const ml = 425; // Mobile large
-const mm = 375; // Mobile medium
-const ms = 320; // Mobile small
-
-module.exports = {
-    media_breakpoints: {
-        xs_min: xs + "px",
-        sm_min: sm + "px",
-        md_min: md + "px",
-        lg_min: lg + "px",
-        xl_min: xl + "px",
-        ml_min: ml + "px",
-        mm_min: mm + "px",
-        ms_min: ms + "px",
-    },
-
-    media_breakpoints_num: {
-        xs,
-        sm,
-        md,
-        lg,
-        xl,
-        ml,
-        mm,
-        ms,
-    },
-};

web/src/css_variables.ts

@@ -0,0 +1,33 @@
+// Media query breakpoints according to Bootstrap 4.5
+const xs = 0;
+const sm = 576;
+const md = 768;
+const lg = 992;
+const xl = 1200;
+
+// Breakpoints for mobile devices used by Google Chrome as of Version 86
+const ml = 425; // Mobile large
+const mm = 375; // Mobile medium
+const ms = 320; // Mobile small
+
+export const media_breakpoints = {
+    xs_min: `${xs}px`,
+    sm_min: `${sm}px`,
+    md_min: `${md}px`,
+    lg_min: `${lg}px`,
+    xl_min: `${xl}px`,
+    ml_min: `${ml}px`,
+    mm_min: `${mm}px`,
+    ms_min: `${ms}px`,
+};
+
+export const media_breakpoints_num = {
+    xs,
+    sm,
+    md,
+    lg,
+    xl,
+    ml,
+    mm,
+    ms,
+};