HTML结构

<div class="line_01">小小分隔线 单标签实现</div>
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<div class="line_02"><span>小小分隔线 巧用色实现</span></div>
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<div class="line_03"><b></b><span>小小分隔线 inline-block实现</span><b></b></div>
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<div class="line_04"><b></b><span>小小分隔线 浮动来实现</span><b></b></div>
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<div class="line_05">———————————<span>小小分隔线 字符来实现</span>————————————</div>

对应的CSS

.demo{width:600px}
.line_01{padding:0 20px 0;margin:20px 0;line-height:1px;border-left:200px solid #ddd;border-right:200px solid #ddd;text-align:center}
.line_02{height:1px;border-top:1px solid #ddd;text-align:center}
.line_02 span{position:relative;top:-12px;background:#fff;padding:0 20px}
.line_03{width:600px}
.line_03 b{background:#ddd;margin-top:4px;display:inline-block;width:180px;height:1px;_overflow:hidden;vertical-align:middle}
.line_03 span{display:inline-block;width:220px;vertical-align:middle;text-align:center}
.line_04{width:600px}
.line_04{overflow:hidden;_zoom:1}
.line_04 b{background:#ddd;margin-top:12px;float:left;width:26%;height:1px;_overflow:hidden}
.line_04 span{padding:0 10px;width:32%;float:left;text-align:center}
.line_05{letter-spacing:-1px;color:#ddd}
.line_05 span{letter-spacing:0;color:#222;margin:0 20px}

演示：点击查看
来源：大前端