51help TIY
码：
<!DOCTYPE html> <html> <head> <style> p:first-child i { background:yellow; } </style> </head> <body> <p>I am a <i>strong</i> man. I am a <i>strong</i> man.</p> <p>I am a <i>strong</i> man. I am a <i>strong</i> man.</p> <p><b>注释：</b>对于 IE8 的 :first-child <!DOCTYPE>。</p> </body> </html>
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