This technique works well for simple gradients that need to expand and contract in a horizontal or vertical direction.

对于需要沿水平或垂直方向扩展或收缩的简单渐变，这种技术是有效的。

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As the armor of horizontal sites like Groupon and LivingSocial begins to dent due to aggressive contract terms, saturation by deal seekers, and shaky financials, market forces are shifting in favor of deal sites from local and niche publishers with an audience, brand authority and sales team already in place.

FORBES: The Trouble With Groupon: Daily Deal Sites Need To Go Local