diff --git a/GeneCodeCS/GeneCodeCS.csproj b/GeneCodeCS/GeneCodeCS.csproj
index 652eb84..6c854aa 100644
--- a/GeneCodeCS/GeneCodeCS.csproj
+++ b/GeneCodeCS/GeneCodeCS.csproj
@@ -17,12 +17,14 @@
     <PackageId>GeneCodeCS</PackageId>
     <PackageTags>genetic-programming;evolutionary-computation;machine-learning</PackageTags>
     <PackageReadmeFile>README.md</PackageReadmeFile>
+    <PackageIcon>icon.png</PackageIcon>
     <RepositoryUrl>https://github.com/EddPorter/GeneCodeCS</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
   </PropertyGroup>
 
   <ItemGroup>
     <None Include="..\README.md" Pack="true" PackagePath="\" />
+    <None Include="icon.png" Pack="true" PackagePath="\" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/GeneCodeCS/icon.png b/GeneCodeCS/icon.png
new file mode 100644
index 0000000..cf9273f
Binary files /dev/null and b/GeneCodeCS/icon.png differ
diff --git a/README.md b/README.md
index 6f656ce..f1012c7 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,4 @@
-GeneCodeCS
-==========
+<p align="center"><img src="https://raw.githubusercontent.com/EddPorter/GeneCodeCS/master/docs/assets/logo-horizontal.png" alt="GeneCodeCS" width="420"></p>
 
 A genetic programming library for performing breeding and natural selection on code bots.
 
diff --git a/docs/assets/apple-touch-icon.png b/docs/assets/apple-touch-icon.png
new file mode 100644
index 0000000..0bbfece
Binary files /dev/null and b/docs/assets/apple-touch-icon.png differ
diff --git a/docs/assets/favicon.ico b/docs/assets/favicon.ico
new file mode 100644
index 0000000..e9798b6
Binary files /dev/null and b/docs/assets/favicon.ico differ
diff --git a/docs/assets/favicon.svg b/docs/assets/favicon.svg
new file mode 100644
index 0000000..18e9c64
--- /dev/null
+++ b/docs/assets/favicon.svg
@@ -0,0 +1,9 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" role="img" aria-labelledby="fav-title">
+  <title id="fav-title">GeneCodeCS favicon</title>
+  <g id="branches" fill="none" stroke="#4f46e5" stroke-width="9" stroke-linecap="round">
+    <path d="M32 17 15 46 M32 17 49 46"/>
+  </g>
+  <circle id="root" cx="32" cy="15" r="12" fill="#4f46e5"/>
+  <circle id="teal-child" cx="14" cy="48" r="12" fill="#0f7b6c"/>
+  <circle id="amber-child" cx="50" cy="48" r="12" fill="#b45309"/>
+</svg>
diff --git a/docs/assets/logo-horizontal.png b/docs/assets/logo-horizontal.png
new file mode 100644
index 0000000..68d356e
Binary files /dev/null and b/docs/assets/logo-horizontal.png differ
diff --git a/docs/assets/logo-horizontal.svg b/docs/assets/logo-horizontal.svg
new file mode 100644
index 0000000..3ac0c37
--- /dev/null
+++ b/docs/assets/logo-horizontal.svg
@@ -0,0 +1,17 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 384 104" role="img" aria-labelledby="horizontal-title horizontal-desc">
+  <title id="horizontal-title">GeneCodeCS</title>
+  <desc id="horizontal-desc">The GeneCodeCS branching program tree beside its coloured wordmark.</desc>
+  <g id="program-mark" transform="translate(0 0) scale(.8125)">
+    <g id="branches" fill="none" stroke="#4f46e5" stroke-width="7" stroke-linecap="round" stroke-linejoin="round">
+      <path d="M64 25 36 49 M64 25 92 49 M36 60 22 83 M36 60 50 83 M92 60 78 83 M92 60 106 83"/>
+    </g>
+    <g id="root" fill="#4f46e5"><circle cx="64" cy="19" r="12"/></g>
+    <g id="left-lineage" fill="#0f7b6c">
+      <circle cx="36" cy="54" r="11"/><circle cx="22" cy="94" r="9"/><circle cx="50" cy="94" r="9"/>
+    </g>
+    <g id="right-lineage" fill="#b45309">
+      <circle cx="92" cy="54" r="11"/><circle cx="78" cy="94" r="9"/><circle cx="106" cy="94" r="9"/>
+    </g>
+  </g>
+  <text id="wordmark" x="104" y="61" font-family='system-ui, -apple-system, "Segoe UI", sans-serif' font-size="35" font-weight="700" letter-spacing="-1"><tspan fill="#4f46e5">Gene</tspan><tspan fill="#0f7b6c">Code</tspan><tspan fill="#b45309">CS</tspan></text>
+</svg>
diff --git a/docs/assets/logo-mark.svg b/docs/assets/logo-mark.svg
new file mode 100644
index 0000000..d16be66
--- /dev/null
+++ b/docs/assets/logo-mark.svg
@@ -0,0 +1,20 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 128 128" role="img" aria-labelledby="mark-title mark-desc">
+  <title id="mark-title">GeneCodeCS mark</title>
+  <desc id="mark-desc">A branching program tree with indigo connections and teal and amber descendant nodes.</desc>
+  <g id="program-branches" fill="none" stroke="#4f46e5" stroke-width="7" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M64 25 36 49 M64 25 92 49 M36 60 22 83 M36 60 50 83 M92 60 78 83 M92 60 106 83"/>
+  </g>
+  <g id="root-node" fill="#4f46e5">
+    <circle cx="64" cy="19" r="12"/>
+  </g>
+  <g id="teal-lineage" fill="#0f7b6c">
+    <circle cx="36" cy="54" r="11"/>
+    <circle cx="22" cy="94" r="9"/>
+    <circle cx="50" cy="94" r="9"/>
+  </g>
+  <g id="amber-lineage" fill="#b45309">
+    <circle cx="92" cy="54" r="11"/>
+    <circle cx="78" cy="94" r="9"/>
+    <circle cx="106" cy="94" r="9"/>
+  </g>
+</svg>
diff --git a/docs/assets/logo-mono.svg b/docs/assets/logo-mono.svg
new file mode 100644
index 0000000..8b56a79
--- /dev/null
+++ b/docs/assets/logo-mono.svg
@@ -0,0 +1,14 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 128 128" role="img" aria-labelledby="mono-title mono-desc">
+  <title id="mono-title">GeneCodeCS monochrome mark</title>
+  <desc id="mono-desc">A single-colour branching program tree.</desc>
+  <g id="program-tree" fill="currentColor" stroke="currentColor" stroke-width="7" stroke-linecap="round" stroke-linejoin="round">
+    <path fill="none" d="M64 25 36 49 M64 25 92 49 M36 60 22 83 M36 60 50 83 M92 60 78 83 M92 60 106 83"/>
+    <circle cx="64" cy="19" r="12" stroke="none"/>
+    <circle cx="36" cy="54" r="11" stroke="none"/>
+    <circle cx="92" cy="54" r="11" stroke="none"/>
+    <circle cx="22" cy="94" r="9" stroke="none"/>
+    <circle cx="50" cy="94" r="9" stroke="none"/>
+    <circle cx="78" cy="94" r="9" stroke="none"/>
+    <circle cx="106" cy="94" r="9" stroke="none"/>
+  </g>
+</svg>
diff --git a/docs/assets/social-preview.png b/docs/assets/social-preview.png
new file mode 100644
index 0000000..9aba79d
Binary files /dev/null and b/docs/assets/social-preview.png differ
diff --git a/docs/assets/social-preview.svg b/docs/assets/social-preview.svg
new file mode 100644
index 0000000..543ef08
--- /dev/null
+++ b/docs/assets/social-preview.svg
@@ -0,0 +1,29 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1280 640" role="img" aria-labelledby="social-title social-desc">
+  <title id="social-title">GeneCodeCS: Evolve programs, not just parameters.</title>
+  <desc id="social-desc">A GitHub social preview featuring the GeneCodeCS program tree logo, wordmark and tagline.</desc>
+  <g id="card-background">
+    <rect width="1280" height="640" fill="#f8fafc"/>
+    <path d="M0 0H1280V12H0Z" fill="#4f46e5"/>
+    <circle cx="1130" cy="120" r="180" fill="#0f7b6c" opacity=".06"/>
+    <circle cx="1200" cy="550" r="220" fill="#b45309" opacity=".05"/>
+  </g>
+  <g id="hero-mark" transform="translate(128 172) scale(2.25)">
+    <g id="tree-branches" fill="none" stroke="#4f46e5" stroke-width="7" stroke-linecap="round" stroke-linejoin="round">
+      <path d="M64 25 36 49 M64 25 92 49 M36 60 22 83 M36 60 50 83 M92 60 78 83 M92 60 106 83"/>
+    </g>
+    <g id="tree-root" fill="#4f46e5"><circle cx="64" cy="19" r="12"/></g>
+    <g id="tree-left-lineage" fill="#0f7b6c">
+      <circle cx="36" cy="54" r="11"/><circle cx="22" cy="94" r="9"/><circle cx="50" cy="94" r="9"/>
+    </g>
+    <g id="tree-right-lineage" fill="#b45309">
+      <circle cx="92" cy="54" r="11"/><circle cx="78" cy="94" r="9"/><circle cx="106" cy="94" r="9"/>
+    </g>
+  </g>
+  <text id="social-wordmark" x="480" y="326" font-family='system-ui, -apple-system, "Segoe UI", sans-serif' font-size="92" font-weight="750" letter-spacing="-3"><tspan fill="#4f46e5">Gene</tspan><tspan fill="#0f7b6c">Code</tspan><tspan fill="#b45309">CS</tspan></text>
+  <g id="social-tagline" font-family='system-ui, -apple-system, "Segoe UI", sans-serif' font-size="32" font-weight="450" fill="#334155">
+    <text x="484" y="389">Evolve programs, not just parameters.</text>
+  </g>
+  <g id="social-footer" font-family='system-ui, -apple-system, "Segoe UI", sans-serif' font-size="20" fill="#64748b">
+    <text x="484" y="452">Genetic programming for .NET</text>
+  </g>
+</svg>
diff --git a/docs/index.html b/docs/index.html
index c78cf27..8a4bb0b 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -5,6 +5,15 @@
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>GeneCodeCS – evolve programs in C#</title>
 <meta name="description" content="GeneCodeCS is a genetic programming library for .NET. Write the small methods your bot may call; it breeds, compiles and ranks programs that combine them.">
+<link rel="icon" href="assets/favicon.svg" type="image/svg+xml">
+<link rel="icon" href="assets/favicon.ico" sizes="48x48">
+<link rel="apple-touch-icon" href="assets/apple-touch-icon.png">
+<meta property="og:type" content="website">
+<meta property="og:title" content="GeneCodeCS: evolve programs, not just parameters">
+<meta property="og:description" content="Genetic programming for .NET. Write the small methods your bot may call; GeneCodeCS breeds, compiles and ranks programs that combine them.">
+<meta property="og:url" content="https://eddporter.github.io/GeneCodeCS/">
+<meta property="og:image" content="https://eddporter.github.io/GeneCodeCS/assets/social-preview.png">
+<meta name="twitter:card" content="summary_large_image">
 <style>
 :root {
   --bg: #fbfaf7; --surface: #ffffff; --surface-2: #f2f0ea; --ink: #1d1f24; --ink-2: #565b66; --line: #dedbd2;
@@ -38,7 +47,8 @@
 
 /* nav + hero */
 nav { display: flex; justify-content: space-between; align-items: center; padding: 18px 0; gap: 16px; }
-nav .brand { font-weight: 800; letter-spacing: -.02em; color: var(--ink); text-decoration: none; }
+nav .brand { display: inline-flex; align-items: center; gap: 10px; font-weight: 800; letter-spacing: -.02em; color: var(--ink); text-decoration: none; }
+nav .brand img { display: block; }
 nav .links { display: flex; gap: 20px; font-size: .95rem; flex-wrap: wrap; justify-content: flex-end; }
 nav .links a { color: var(--ink-2); text-decoration: none; }
 nav .links a:hover { color: var(--ink); }
@@ -159,7 +169,7 @@
 <body>
 <div class="wrap">
   <nav aria-label="Main">
-    <a class="brand" href="#top">GeneCodeCS</a>
+    <a class="brand" href="#top"><img src="assets/logo-mark.svg" alt="" width="32" height="32">GeneCodeCS</a>
     <div class="links">
       <a href="#demo">Live demo</a>
       <a href="#how">How it works</a>