midori/data/gtk3.css

.notebook tab .button {
    -GtkButton-default-border: 0;
    -GtkButton-default-outside-border: 0;
    -GtkButton-inner-border: 0;
    -GtkWidget-focus-line-width: 0;
    -GtkWidget-focus-padding: 0;
    padding: 0;
}

GtkOverlay > * {
    padding: 4px;
    border-style: solid;
    border-radius: 0 5px 0 0;
    border-width: 1px 1px 0 0;
}

GtkOverlay MidoriFindbar {
    border-radius: 0 0 0 5px;
    border-width: 0 0 1px 1px; /* top right bottom left */
}

/* Kill grey backround on inactive buttons */
GtkDrawingArea,
GtkImage,
GtkImage:insensitive,
GtkImage:selected {
    background-color: @transparent;
}