Decoration: make outline more outliney

The current outline is so subtle as to be almost invisible even with
Breeze Dark, and actually invisible (by design) on Breeze Light. Thus it
doesn't serve its purpose of being an outline that well.

This commit makes it more contrasty, so that it's an actual outline more
of the time.

kdecoration/breezedecoration.cpp

@@ -759,16 +759,7 @@ void Decoration::updateShadow()
                          outlineColor.hslSaturationF(),
                          qBound(0.1, outlineColor.lightnessF(), 1.0),
                          s->isAlphaChannelSupported() ? 0.9 : 1.0);
-    // If outlinecolor is very close to the window backgroundcolor, the shadow coloring should be enough,
-    // so we use the background color as the outline as well.
-    // This is only checked for very light colors, like the default Breeze Light (#e5e6e7)
-    // If not, we just modify the lightness like usual
-    if (!lookupShadowParams(m_internalSettings->shadowSize()).isNone() && backgroundColor.lightnessF() >= 0.85
-        && (backgroundColor.lightnessF() - outlineColor.lightnessF()) <= 0.05f) {
-        outlineColor = backgroundColor;
-    } else {
-        outlineColor.lightnessF() >= 0.5 ? outlineColor = outlineColor.darker(130) : outlineColor = outlineColor.lighter(130);
-    }
+    outlineColor.lightnessF() >= 0.5 ? outlineColor = outlineColor.darker(170) : outlineColor = outlineColor.lighter(170);
 
     // Animated case, no cached shadow object
     if ((m_shadowAnimation->state() == QAbstractAnimation::Running) && (m_shadowOpacity != 0.0) && (m_shadowOpacity != 1.0)) {