.one {
    color: blue !important;
}

.one {
    color: red;
}
.two {
    color: yellow;
}
.three {
    color: green;
}

#test {
    color: palevioletred;
}
#test {
    color: teal;
}

.meun {

}

.meun ul li,
.logo h1{
    color: rebeccapurple; 
}

.gghh:hover {
    color: green;
}
.username:focus {
    background: yellow;
    width: 300px;
}
.be::before {
    content: "测试1 ";
}
.be::after {
    content: " 测试2";
}
/* .koko li:first-child {
    color: red;
}
.koko li:last-child {
    color: red;
} */

.koko li:nth-child(4n) {
    color: red;
}
.gl::selection {
    background: yellow;
    color: red;
}
.login input[placeholder="用户名"] {
    background: blue;
}
.login input[placeholder="验证码"] {
    background: green;
}