1 files changed, 51 insertions, 0 deletions
diff --git a/packages/instant/src/style/media.ts b/packages/instant/src/style/media.ts
new file mode 100644
index 000000000..bbf376694
--- /dev/null
+++ b/packages/instant/src/style/media.ts
@@ -0,0 +1,51 @@
+import { InterpolationValue } from 'styled-components';
+
+import { css } from './theme';
+
+export enum ScreenWidths {
+    Sm = 40,
+    Md = 52,
+    Lg = 64,
+}
+
+export const generateMediaWrapper = (screenWidth: ScreenWidths) => (...args: any[]) => css`
+    @media (max-width: ${screenWidth}em) {
+        ${css.apply(css, args)};
+    }
+`;
+
+export const media = {
+    small: generateMediaWrapper(ScreenWidths.Sm),
+    medium: generateMediaWrapper(ScreenWidths.Md),
+    large: generateMediaWrapper(ScreenWidths.Lg),
+};
+
+export interface ScreenSpecification<T> {
+    default: T;
+    sm?: T;
+    md?: T;
+    lg?: T;
+}
+export type OptionallyScreenSpecific<T> = T | ScreenSpecification<T>;
+export type MediaChoice = OptionallyScreenSpecific<string>;
+/**
+ * Given a css property name and a OptionallyScreenSpecific value,
+ * generates css properties with screen-specific viewport styling
+ */
+export function stylesForMedia<T extends string | number>(
+    cssPropertyName: string,
+    choice: OptionallyScreenSpecific<T>,
+): InterpolationValue[] {
+    if (typeof choice === 'object') {
+        return css`
+        ${cssPropertyName}: ${choice.default};
+        ${choice.lg && media.large`${cssPropertyName}: ${choice.lg}`}
+        ${choice.md && media.medium`${cssPropertyName}: ${choice.md}`}
+        ${choice.sm && media.small`${cssPropertyName}: ${choice.sm}`}
+    `;
+    } else {
+        return css`
+            ${cssPropertyName}: ${choice};
+        `;
+    }
+}