Solved:
"QTreeWidget { border: none; }"
"QTreeWidget::indicator:checked { border-image: url(:/images/checkbox_checked.png); }"
"QTreeWidget::indicator:unchecked { border-image: url(:/images/checkbox_unchecked.png); }"
"QScrollBar:vertical { border-image: url(:/images/scroll.png); width: 25px; margin: 0px;}"
"QScrollBar::handle:vertical { min-height: 20px; margin: 10px 7px 40px 7px; border-radius: 4px;"
background: qlineargradient(x1: 0, y1: 0, x2: 1, y2: 1, stop: 0 #4c443d, stop: 1 #2f2b26); }"
"QScrollBar::add-page:vertical { background: none; }"
"QScrollBar::sub-page:vertical { background: none; }"
"QScrollBar::add-line:vertical { /*margin-bottom: 21px;*/ height: 21px; subcontrol-position: bottom; subcontrol-origin: content; border: none;}"
"QScrollBar::sub-line:vertical { margin-top: 21px; height: 18px; subcontrol-position: bottom; subcontrol-origin: content; border: none;}"
"QScrollBar::up-arrow:vertical, QScrollBar::down-arrow:vertical { background: none; }"
"QHeaderView::section{ background: transparent; border-bottom: 1px solid qlineargradient(x1: 0, y1: 0, x2: 1, y2: 1,"
stop: 0 #9DBCBC, stop: 1 #CBCBCB); border-top: none; border-left: none; }"
"QHeaderView::section:first { background: transparent; border-right: 1px solid qlineargradient(x1: 0, y1: 0, x2: 1, y2: 1,"
"stop: 0 #9DBCBC, stop: 1 #CBCBCB);; }";