code: function getBordersSize(styles, ...positions) {
      return positions.reduce((size, position) => {
          const value = styles['border-' + position + '-width'];
  
          return size + toFloat(value);
      }, 0);
  }
docs: Extracts borders size from provided styles.
  
  @param {CSSStyleDeclaration} styles
  @param {...string} positions - Borders positions (top, right, ...)
  @returns {number}