placeholder样式

    input::-webkit-input-placeholder {
      color: palevioletred;
    }
    input::-moz-placeholder {
      color: palevioletred;
    }
    input:-ms-input-placeholder {
      color: palevioletred;
    }
    input::-webkit-input-placeholder {
      color: palevioletred;
    }
    input::placeholder {
      color: palevioletred;
    }