Qt sets the style of the parent form without affecting the style of the child control and the transparency of the child control

1. The parent form style does not take effect?

   this->setAttribute(Qt::WA_StyledBackground);

2. Does the style of the parent window affect the child controls?

this->setStyleSheet("#objname{background-color: rgb(190,190,190)});

3. Is the child control qlinedit set to be transparent and borderless?

 ui->btnLoad->setStyleSheet("background:transparent;border-width:0;border-style:outset");