# 选择符 ``` <pre class="calibre19">``` <span class="token">!</span>important 优先权 transparent背景透明 inherit 继承父级样式 <span class="token1">rgba</span><span class="token2">(</span><span class="token3">125</span><span class="token2">,</span> <span class="token3">0</span><span class="token2">,</span> <span class="token3">0</span><span class="token2">,</span> <span class="token3">.3</span><span class="token2">)</span><span class="token2">;</span> ``` ``` 选择符 ``` <pre class="calibre16">``` E F 包含 E<span class="token">></span>F 子类 E<span class="token">+</span>F 相邻 E<span class="token">~</span>F兄弟 E<span class="token2">[</span>att<span class="token">=</span><span class="token4">"val"</span><span class="token2">]</span> 属性 a<span class="token2">:</span>link<span class="token2">{</span><span class="token2">}</span> a<span class="token2">:</span>visited<span class="token2">{</span><span class="token2">}</span> a<span class="token2">:</span>hover<span class="token2">{</span><span class="token2">}</span> a<span class="token2">:</span>active<span class="token2">{</span><span class="token2">}</span> input<span class="token2">:</span>focus<span class="token2">{</span><span class="token2">}</span>获得焦点 E<span class="token2">:</span>first<span class="token">-</span>child 第一个 E<span class="token2">:</span>last<span class="token">-</span>child 最后一个 li<span class="token2">:</span>nth<span class="token">-</span><span class="token1">child</span><span class="token2">(</span><span class="token3">2</span>n<span class="token2">)</span><span class="token2">{</span>color<span class="token2">:</span>#f00<span class="token2">;</span><span class="token2">}</span> 偶数 li<span class="token2">:</span>nth<span class="token">-</span><span class="token1">child</span><span class="token2">(</span><span class="token3">2</span>n<span class="token">+</span><span class="token3">1</span><span class="token2">)</span><span class="token2">{</span>color<span class="token2">:</span>#<span class="token3">000</span><span class="token2">;</span><span class="token2">}</span> 奇数 E<span class="token2">:</span><span class="token2">:</span>before 之前 E<span class="token2">:</span><span class="token2">:</span>after 之后 p<span class="token2">:</span><span class="token2">:</span>selection<span class="token2">{</span>background<span class="token2">:</span>#<span class="token3">000</span><span class="token2">;</span>color<span class="token2">:</span>#f00<span class="token2">;</span><span class="token2">}</span> 只能定义背景字体颜色 ``` ```