Add a new muted text color.

gpt4all-chat/main.qml

@@ -803,7 +803,7 @@ Window {
                 wrapMode: Text.WordWrap
                 font.pixelSize: theme.fontSizeLarge
                 placeholderText: qsTr("Send a message...")
-                placeholderTextColor: theme.backgroundLightest
+                placeholderTextColor: theme.mutedTextColor
                 background: Rectangle {
                     color: theme.backgroundLighter
                     radius: 10

gpt4all-chat/qml/Theme.qml

@@ -4,6 +4,7 @@ import QtQuick.Controls.Basic
 
 QtObject {
     property color textColor: "#d1d5db"
+    property color mutedTextColor: backgroundLightest
     property color textErrorColor: "red"
     property color backgroundDarkest: "#202123"
     property color backgroundDarker: "#222326"