Teemavalitsin: painike kiertää gecko/forge/serpent, oletus forge

- Teemapainike (emoji) oikeaan yläkulmaan kuten kipina.tech:ssä
- Oletus forge (syaani), tallennetaan localStorage:iin
- Hero-kuva vaihtuu teeman mukaan fade-efektillä
- Kolme hero-kuvaa: gecko_hero, forge_hero (hämähäkki), serpent_hero

network-poc/frontend/src/pages/index.astro

@@ -32,6 +32,7 @@ import Settings from "../components/Settings.astro";
         <div class="bg-mesh"></div>
         <header class="landing-nav">
             <a href="/" class="landing-logo"><span class="logo-accent">KIPINÄ</span> <span class="logo-sub">/ agentic studio</span></a>
+            <button id="theme-cycle-btn" class="theme-cycle-btn" title="Vaihda teemaa"></button>
         </header>
 
         <section class="hero">
@@ -136,11 +137,18 @@ import Settings from "../components/Settings.astro";
     </div>
 
     <script is:inline>
-    // === Teeman satunnaisvalinta (gecko/forge/serpent) ===
+    // === Teemajärjestelmä (gecko/forge/serpent) — oletus forge ===
+    const KS_THEMES = [
+        { id: 'gecko', icon: '\u{1F98E}' },
+        { id: 'forge', icon: '\u{2699}\u{FE0F}' },
+        { id: 'serpent', icon: '\u{1F40D}' }
+    ];
+    const KS_DEFAULT = 'forge';
     (function() {
-        const themes = ['gecko', 'forge', 'serpent'];
-        const theme = themes[Math.floor(Math.random() * themes.length)];
-        document.documentElement.setAttribute('data-theme', theme);
+        let saved = KS_DEFAULT;
+        try { saved = localStorage.getItem('kipina-studio-theme') || KS_DEFAULT; } catch(_){}
+        if (!KS_THEMES.find(t => t.id === saved)) saved = KS_DEFAULT;
+        document.documentElement.setAttribute('data-theme', saved);
     })();
 
     // === Helpers ===
@@ -149,6 +157,32 @@ import Settings from "../components/Settings.astro";
         d.style.display = d.style.display === 'none' ? 'block' : 'none';
     };
 
+    // === Teemapainike: kierrätys + hero-kuvan vaihto ===
+    (function() {
+        const btn = document.getElementById('theme-cycle-btn');
+        const heroImg = document.querySelector('.hero-orb-img');
+        function currentTheme() { return document.documentElement.getAttribute('data-theme') || KS_DEFAULT; }
+        function applyTheme(themeId) {
+            document.documentElement.setAttribute('data-theme', themeId);
+            const t = KS_THEMES.find(x => x.id === themeId) || KS_THEMES[1];
+            if (btn) btn.textContent = t.icon;
+            if (heroImg) {
+                heroImg.style.opacity = '0';
+                setTimeout(() => { heroImg.src = '/' + themeId + '_hero.webp'; heroImg.style.opacity = '1'; }, 200);
+            }
+            try { localStorage.setItem('kipina-studio-theme', themeId); } catch(_){}
+        }
+        // Alkuasetus
+        applyTheme(currentTheme());
+        // Klikkaus kiertää seuraavaan
+        if (btn) btn.addEventListener('click', () => {
+            const cur = currentTheme();
+            const idx = KS_THEMES.findIndex(t => t.id === cur);
+            const next = KS_THEMES[(idx + 1) % KS_THEMES.length];
+            applyTheme(next.id);
+        });
+    })();
+
     function esc(str) {
         if (!str) return '';
         return String(str).replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;').replace(/"/g,'&quot;');

network-poc/frontend/src/styles/global.css

@@ -290,10 +290,20 @@ body {
 
 .landing-nav {
     padding: 20px 40px;
+    display: flex; align-items: center; justify-content: space-between;
 }
 .landing-logo { text-decoration: none; font-size: 18px; font-weight: 700; }
 .logo-accent { color: var(--hero-accent); }
 .logo-sub { color: #8b949e; font-weight: 400; }
+.theme-cycle-btn {
+    background: none; border: 1px solid var(--border); border-radius: 8px;
+    width: 38px; height: 38px; font-size: 20px; cursor: pointer;
+    display: flex; align-items: center; justify-content: center;
+    transition: border-color 0.2s, transform 0.15s;
+}
+.theme-cycle-btn:hover {
+    border-color: var(--hero-accent); transform: scale(1.1);
+}
 
 /* Hero */
 .hero {
@@ -380,6 +390,7 @@ body {
 .hero-orb-img {
     width: 100%; height: 100%; object-fit: contain;
     filter: drop-shadow(0 0 40px var(--hero-glow));
+    transition: opacity 0.2s ease;
 }
 @keyframes orb-float {
     0%, 100% { transform: translateY(0); }