message: Adds a function for calculating actual line-heights
diff: import { css } from 'styled-components';
  -export default {
  - size: {
  +const size = {
  root: {
  desktop: '16px',
  mobile: '13px',
  @@ -18,12 +17,16 @@ export default {
  h4: '1.5rem',
  h5: '1.25rem',
  h6: '1rem',
  - },
  +};
  - lineHeight: {
  +const lineHeight = {
  base: 1.33,
  tall: 1.5,
  - },
  +};
  +
  +export default {
  + size,
  + lineHeight,
  font: {
  sans: "'Arial', 'Helvetica Neue', 'Helvetica', sans-serif",
  @@ -37,4 +40,12 @@ export default {
  -moz-osx-font-smoothing: grayscale;
  `,
  },
  +
  + functions: {
  + calculateLineHeight(fontSizeName, lineHeightName) {
  + const fontSizeValue = parseFloat(size[fontSizeName], 10);
  + const lineHeightValue = lineHeight[lineHeightName];
  + return fontSizeValue * lineHeightValue;
  + },
  + },
  };
  