feat(theme): add support for custom themes

src/scripts/theme.js

@@ -0,0 +1,29 @@
+const LIGHT_THEME = {
+  'primary-text': '#25313b',
+  'neutral-text': '#777',
+  'background': '#fff',
+  'hover-background': '#eee',
+};
+const DARK_THEME = {
+  'primary-text': '#8A9EBA',
+  'neutral-text': '#36527A',
+  'background': '#22272e',
+  'hover-background': '#30404D',
+};
+
+let THEME;
+
+const normalizeKey = (k) =>
+  k
+    .replace(/([A-Z])/g, '-$1')
+    .toLowerCase()
+    .replace(/^theme-/, '');
+
+export const loadTheme = (props, style) => {
+  THEME = props.theme == 'dark' ? DARK_THEME : LIGHT_THEME;
+  Object.entries(props)
+    .filter(([k, v]) => v && /^theme[A-Z]/.test(k))
+    .map(([k, v]) => [normalizeKey(k), v])
+    .forEach(([k, v]) => (THEME[k] = v));
+  Object.entries(THEME).forEach(([k, v]) => style.setProperty(`--${k}`, v));
+};