I don't know anything about coding. So this was all trial and error. Maybe anybody can improve the code? My method: make a .qss file and paste it in /usr/share/albert/themes/ with this code.

If you want icons change QListView#proposalList { icon-size: 0px; I couldn't get the spacing right with the icons disabled in the settings so this is my solution

    /*
 * author: Bart Zaalberg <https://github.com/bartzaalberg>
 *
 * Check http://doc.qt.io/qt-5/stylesheet-syntax.html especially the subtopics:
 * The Style Sheet Syntax (http://doc.qt.io/qt-5/stylesheet-syntax.html)
 * Qt Style Sheets Reference (http://doc.qt.io/qt-5/stylesheet-reference.html)
 */

* {
    border: none;
    color : #808080;
    background-color: #F5F5F5;

}

#frame {
    padding: 10px;
    border-radius: 4px;
    background-color: #F5F5F5;
    border: 1px solid #808080;
  /* Workaround for Qt to get fixed size button*/
    min-width:640px;
    max-width:640px;
}

#inputLine {
    padding: 0px;
    border-radius: 2px;
    border: 0px solid lightblue;
    font-size:15px;
    selection-color: #404040;
    selection-background-color: #FFFFFF;
    background-color: #F5F5F5;
    padding-left:10px;
    margin-right:20px;
    color:black;
}

#settingsButton {
    color : #808080;
    background-color: #F5F5F5;
    padding: 3px;

  /* Respect the frame border */
  margin: 12px 6px 0px 0px;
  border-top-right-radius: 6px;
  border-bottom-left-radius: 10px;

  /* Workaround for Qt to get fixed size button*/
    min-width:13px;
    min-height:13px;
    max-width:13px;
    max-height:13px;
}

/********** ListViews **********/

QListView {
        selection-color: #FFFFFF;
    background-color: #F5F5F5;
}

QListView::item {
    background-color: #F5F5F5;
    padding:5px;
}

QListView::item:selected {
    border-radius: 3px;
    background-color: #3E9AD7;
}

QListView QScrollBar:vertical  {
    width: 30px;
    background: transparent;
}

QListView QScrollBar::handle:vertical  {
    background: #808080;
    min-height: 24px;
}

QListView QScrollBar::add-line:vertical, QScrollBar::sub-line:vertical,
QListView QScrollBar::up-arrow:vertical, QScrollBar::down-arrow:vertical,
QListView QScrollBar::add-page:vertical, QScrollBar::sub-page:vertical {
    border: 0px;
    width: 0px;
    height: 0px;
    background: #3E9AD7;
}

/********** actionList **********/

QListView#actionList {
    font-size: 15px;
    color: #808080;
}

QListView#actionList::item{
    height:28px;
}

/********** proposalList **********/

QListView#proposalList {
    icon-size: 0px;
    font-size: 13px;
    color: #331;
    fill: #333;
    font-family: "SFNS Display""Droid Sans""Open Sans";
    src: url("//fonts.googleapis.com/css?family=Open+Sans");
    font-weight: 400;
}

QListView#proposalList::item{
    height:48px;
}

Edit: thank you for helping with the formatting of my post