QFD2/QFluentWidgets/qss/light/tree_view.qss

QTreeView {
    background-color: transparent;
    border: none;
    border-radius: 5px;
    outline: 0;
    padding-right: 5px;
    font: 16px 'Segoe UI', 'Microsoft YaHei';
    selection-background-color: transparent;
}

QTreeView::item {
    padding: 4px;
    margin-top: 2px;
    margin-bottom: 2px;
    padding-left: 20px;
    border-radius: 5px;
    color: black;
}

QTreeView::branch:has-children:!has-siblings:closed,
QTreeView::branch:closed:has-children:has-siblings {
    image: url(:/qfluentwidgets/images/tree_view/TreeViewClose_black.svg);
}

QTreeView::branch:open:has-children:!has-siblings,
QTreeView::branch:open:has-children:has-siblings {
    image: url(:/qfluentwidgets/images/tree_view/TreeViewOpen_black.svg);
}

QTreeView:disabled {
    color: rgba(0, 0, 0, 110);
}

QTreeView::indicator {
    width: 18px;
    height: 18px;
    border-radius: 5px;
    border: 1px solid rgb(135, 135, 135);
    background-color: rgb(241, 241, 241);
}

QTreeView::indicator:hover {
    border: 1px solid rgb(132, 132, 132);
    background-color: rgb(232, 232, 232);
}

QTreeView::indicator:pressed {
    border: 1px solid rgb(184, 184, 184);
    background-color: rgb(224, 224, 224);
}

QTreeView::indicator:checked,
QTreeView::indicator:indeterminate {
    border: 1px solid --ThemeColorPrimary;
    background-color: --ThemeColorPrimary;
}

QTreeView::indicator:checked {
    image: url(:/qfluentwidgets/images/check_box/Accept_white.svg);
}

QTreeView::indicator:indeterminate {
    image: url(:/qfluentwidgets/images/check_box/PartialAccept_white.svg);
}

QTreeView::indicator:checked:hover,
QTreeView::indicator:indeterminate:hover {
    border: 1px solid --ThemeColorLight1;
    background-color: --ThemeColorLight1;
}

QTreeView::indicator:checked:pressed,
QTreeView::indicator:indeterminate:pressed {
    border: 1px solid --ThemeColorLight3;
    background-color: --ThemeColorLight3;
}

QTreeView::indicator:disabled {
    border: 1px solid #bbbbbb;
    background-color: rgb(224, 224, 224);
}

QTreeView::indicator:checked:disabled,
QTreeView::indicator:indeterminate:disabled {
    border: 1px solid rgb(199, 199, 199);
    background-color: rgb(199, 199, 199);
}


QScrollBar {
    background: transparent;
    width: 4px;
    margin-top: 12px;
    margin-bottom: 0;
    padding-right: 2px;
}

QScrollBar::sub-line {
    background: transparent;
}

QScrollBar::add-line {
    background: transparent;
}

QScrollBar::handle {
    background: rgb(122, 122, 122);
    border: 2px solid rgb(128, 128, 128);
    border-radius: 1px;
    min-height: 32px;
}

QScrollBar::add-page:vertical,
QScrollBar::sub-page:vertical {
    background: none;
}