<style scoped lang="scss">
/deep/.el-textarea input::-moz-input-placeholder {
  font-family:"Microsoft";
  color:#C0C4CC;
}
/deep/.el-textarea__inner::-webkit-input-placeholder {
  font-family:"Microsoft";
  color:#C0C4CC;
}
</style>

或者

<style  lang="scss" scoped>
//修改字體顏色大小：
  /deep/.input_remark1 .el-textarea__inner {
    color: #101010;
  }
//修改未輸入時字體大小和顏色
  /deep/.sale_sel .el-input--small {
    color: #101010;
    font-size: 14px;
  }
</style>