fix(cv): enforce readable render palettes

Choose a contrasting header foreground for custom accents and keep public colour and font overrides inside safe supported values.

JobTrackerApi/Services/ThemedCvRenderer.cs

@@ -22,6 +22,7 @@ public sealed class ThemedCvRenderer : IThemedCvRenderer
     {
         settings = CvVariantSettingsJson.Normalize(settings);
         var accent = Override(settings.AccentColor, theme.Accent);
+        var headerInk = ContrastInk(accent);
         var headingColor = theme.HeadingColor ?? accent;
         var headingFont = Override(settings.HeadingFont, theme.HeadingFont);
         var bodyFont = Override(settings.BodyFont, theme.BodyFont);
@@ -35,7 +36,7 @@ public sealed class ThemedCvRenderer : IThemedCvRenderer
             ? SplitColumns(model, theme, showIcons)
             : (string.Empty, RenderSections(model.Sections, theme));
 
-        var css = BuildCss(theme, accent, headingColor, headingFont, bodyFont, density, pageDims, twoColumn);
+        var css = BuildCss(theme, accent, headerInk, headingColor, headingFont, bodyFont, density, pageDims, twoColumn);
         var header = RenderHeader(model, theme, showIcons, twoColumn);
         var body = theme.Layout switch
         {
@@ -189,7 +190,7 @@ public sealed class ThemedCvRenderer : IThemedCvRenderer
         return s;
     }
 
-    private static string BuildCss(CvTheme t, string accent, string headingColor, string headingFont, string bodyFont, double density, (string w, string h) page, bool twoColumn)
+    private static string BuildCss(CvTheme t, string accent, string headerInk, string headingColor, string headingFont, string bodyFont, double density, (string w, string h) page, bool twoColumn)
     {
         var margin = F(t.PageMarginMm * density);
         var sectionGap = F(t.SectionGapMm * density);
@@ -209,13 +210,14 @@ public sealed class ThemedCvRenderer : IThemedCvRenderer
 .sidebar{{background:{t.SidebarBg};color:{t.SidebarInk};padding:{margin}mm;}}
 .sidebar .section-title{{color:{t.SidebarInk};border-color:rgba(255,255,255,.35);}}
 .sidebar .tag{{border-color:rgba(255,255,255,.4);}}
+.sidebar .contact,.sidebar .headline,.sidebar .entry-meta,.sidebar .entry-subtitle{{color:{t.SidebarInk};}}
 .sidebar a{{color:inherit;}}
 .main{{padding:{margin}mm;}}
 .hero .name{{color:{t.SidebarInk};}}"
             : $@".main{{padding:0 {margin}mm {margin}mm {margin}mm;}}
 .header{{padding:{margin}mm {margin}mm {F(t.SectionGapMm * density)}mm {margin}mm;display:flex;gap:6mm;align-items:center;}}
-.header-band{{background:{accent};color:#fff;}}
-.header-band .name,.header-band .headline,.header-band a{{color:#fff;}}
+.header-band{{background:{accent};color:{headerInk};}}
+.header-band .name,.header-band .headline,.header-band .contact,.header-band .contact-item,.header-band a{{color:{headerInk};}}
 .header-centered{{flex-direction:column;text-align:center;justify-content:center;}}
 .header-centered .contact{{justify-content:center;}}
 .header-plain{{border-bottom:2px solid {accent};}}";
@@ -293,6 +295,21 @@ h1,h2{{font-family:{headingFont};}}
         $@"<svg viewBox=""0 0 16 16"" fill=""none"" stroke=""currentColor"" stroke-width=""1.3"" stroke-linecap=""round"" stroke-linejoin=""round""><path d=""{path}""/></svg>";
 
     private static string Override(string? value, string fallback) => string.IsNullOrWhiteSpace(value) ? fallback : value.Trim();
+
+    private static string ContrastInk(string background)
+    {
+        if (background.Length != 7 || background[0] != '#' || !background.Skip(1).All(Uri.IsHexDigit)) return "#000";
+
+        var r = Convert.ToInt32(background.Substring(1, 2), 16) / 255d;
+        var g = Convert.ToInt32(background.Substring(3, 2), 16) / 255d;
+        var b = Convert.ToInt32(background.Substring(5, 2), 16) / 255d;
+        static double Channel(double value) => value <= 0.04045 ? value / 12.92 : Math.Pow((value + 0.055) / 1.055, 2.4);
+        var luminance = 0.2126 * Channel(r) + 0.7152 * Channel(g) + 0.0722 * Channel(b);
+        var whiteContrast = 1.05 / (luminance + 0.05);
+        var blackContrast = (luminance + 0.05) / 0.05;
+        return whiteContrast >= blackContrast ? "#fff" : "#000";
+    }
+
     private static string F(double v) => v.ToString("0.##", CultureInfo.InvariantCulture);
     private static string Enc(string? v) => WebUtility.HtmlEncode(v ?? string.Empty);
     private static string Attr(string? v) => WebUtility.HtmlEncode(v ?? string.Empty).Replace("'", "&#39;", StringComparison.Ordinal);