WH Smith reported a fall in sales in the 18 weeks to 27 July, but the newsagent and bookshop chain said it is continuing to grow margins.Total sales were down by 1% from the same period the previous year, or by 4% on a like-for-like basis, excluding the impact of new openings. In the travel division, which operates in railway stations and airports, total sales were up by 2%, but like-for-like sales fell by 2%. The company "saw a further period of gross margin expansion."High street sales were down by 3% overall and by 4% on a like-for-like basis. Gross margins also grew in the division. WH Smith has been shifting its sales into higher margin areas, moving out of categories such as entertainment."The economic environment remains uncertain and whilst we continue to be cautious about consumer spending, we remain confident in the outcome for the full year," WH Smith said.---RG