diff --git a/internal/server/admin/static/index.html b/internal/server/admin/static/index.html
index d22c40e..37a52b6 100644
--- a/internal/server/admin/static/index.html
+++ b/internal/server/admin/static/index.html
@@ -15,6 +15,7 @@
       --accent: #3b82f6;
       --ok: #22c55e;
       --err: #ef4444;
+      --sidebar-w: 260px;
     }
     * { box-sizing: border-box; margin: 0; padding: 0; }
     body {
@@ -24,40 +25,135 @@
       min-height: 100vh;
       line-height: 1.5;
     }
-    .page {
-      max-width: 1000px;
-      margin: 0 auto;
-      padding: 2rem 1.5rem;
+    .app {
+      display: flex;
+      min-height: 100vh;
     }
-    header {
-      margin-bottom: 2rem;
-      padding-bottom: 1.5rem;
+    .sidebar {
+      width: var(--sidebar-w);
+      flex-shrink: 0;
+      background: var(--surface);
+      border-right: 1px solid var(--border);
+      display: flex;
+      flex-direction: column;
+      position: sticky;
+      top: 0;
+      height: 100vh;
+      overflow: hidden;
+    }
+    .sidebar-brand {
+      padding: 1.25rem 1rem 1rem;
       border-bottom: 1px solid var(--border);
     }
-    header h1 { font-size: 1.5rem; font-weight: 600; }
-    header p { color: var(--muted); margin-top: 0.25rem; font-size: 0.9rem; }
-    .grid {
-      display: grid;
-      gap: 1rem;
-      grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
+    .sidebar-brand h1 { font-size: 1.1rem; font-weight: 600; }
+    .sidebar-brand p { color: var(--muted); font-size: 0.8rem; margin-top: 0.2rem; }
+    .sidebar-nav {
+      flex: 1;
+      overflow-y: auto;
+      padding: 0.5rem 0;
     }
-    .card {
+    .nav-section { margin-bottom: 0.25rem; }
+    .nav-section-header {
+      display: flex;
+      align-items: center;
+      gap: 0.5rem;
+      width: 100%;
+      padding: 0.55rem 1rem;
+      background: none;
+      border: none;
+      color: var(--text);
+      font-size: 0.875rem;
+      font-weight: 600;
+      cursor: pointer;
+      text-align: left;
+    }
+    .nav-section-header:hover { background: rgba(255,255,255,0.04); }
+    .nav-section-header.active { color: var(--accent); }
+    .nav-chevron {
+      width: 0.65rem;
+      height: 0.65rem;
+      border-right: 2px solid var(--muted);
+      border-bottom: 2px solid var(--muted);
+      transform: rotate(-45deg);
+      transition: transform 0.15s;
+      flex-shrink: 0;
+      margin-left: auto;
+    }
+    .nav-chevron.open { transform: rotate(45deg); margin-top: -0.2rem; }
+    .nav-children {
+      padding: 0.15rem 0 0.35rem;
+    }
+    .nav-item {
+      display: block;
+      width: 100%;
+      padding: 0.4rem 1rem 0.4rem 1.75rem;
+      background: none;
+      border: none;
+      color: var(--muted);
+      font-size: 0.82rem;
+      text-align: left;
+      cursor: pointer;
+      white-space: nowrap;
+      overflow: hidden;
+      text-overflow: ellipsis;
+    }
+    .nav-item:hover { color: var(--text); background: rgba(255,255,255,0.04); }
+    .nav-item.selected {
+      color: var(--text);
+      background: rgba(59, 130, 246, 0.15);
+      border-right: 2px solid var(--accent);
+    }
+    .nav-item.add {
+      color: var(--accent);
+      font-weight: 500;
+    }
+    .nav-item.add:hover { background: rgba(59, 130, 246, 0.1); }
+    .nav-empty {
+      padding: 0.25rem 1rem 0.25rem 1.75rem;
+      font-size: 0.78rem;
+      color: var(--muted);
+      font-style: italic;
+    }
+    .sidebar-footer {
+      padding: 1rem;
+      border-top: 1px solid var(--border);
+    }
+    .sidebar-footer label { font-size: 0.75rem; color: var(--muted); display: block; margin-bottom: 0.35rem; }
+    .sidebar-footer input {
+      width: 100%;
+      padding: 0.4rem 0.6rem;
+      background: var(--bg);
+      border: 1px solid var(--border);
+      border-radius: 6px;
+      color: var(--text);
+      font-size: 0.78rem;
+    }
+    .api-status { font-size: 0.75rem; margin-top: 0.35rem; }
+    .api-status.ok { color: var(--ok); }
+    .api-status.err { color: var(--err); }
+
+    .main {
+      flex: 1;
+      min-width: 0;
+      padding: 2rem 2rem 3rem;
+      max-width: 900px;
+    }
+    .main-header {
+      margin-bottom: 1.5rem;
+      padding-bottom: 1rem;
+      border-bottom: 1px solid var(--border);
+    }
+    .main-header h2 { font-size: 1.35rem; font-weight: 600; }
+    .main-header p { color: var(--muted); margin-top: 0.25rem; font-size: 0.9rem; }
+
+    .panel {
       background: var(--surface);
       border: 1px solid var(--border);
       border-radius: 10px;
-      padding: 1.25rem;
-    }
-    .card.wide { grid-column: 1 / -1; }
-    .card h2 {
-      font-size: 0.75rem;
-      text-transform: uppercase;
-      letter-spacing: 0.06em;
-      color: var(--muted);
-      margin-bottom: 0.75rem;
+      padding: 1.5rem;
     }
     .muted { color: var(--muted); font-size: 0.85rem; margin-top: 0.5rem; }
     button {
-      margin-top: 1rem;
       padding: 0.5rem 1rem;
       background: var(--accent);
       color: #fff;
@@ -74,17 +170,16 @@
       color: var(--accent);
     }
     button.secondary:hover { background: rgba(59, 130, 246, 0.12); filter: none; }
-    .btn-row { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 1rem; }
+    .btn-row { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 1.25rem; align-items: center; }
     button.danger {
       background: transparent;
       border: 1px solid var(--err);
       color: var(--err);
-      margin-top: 0;
-      padding: 0.35rem 0.65rem;
-      font-size: 0.8rem;
+      padding: 0.5rem 1rem;
+      font-size: 0.875rem;
     }
     button.danger:hover { background: rgba(239, 68, 68, 0.12); filter: none; }
-    input {
+    input, select {
       width: 100%;
       margin-top: 0.5rem;
       padding: 0.5rem 0.75rem;
@@ -101,65 +196,28 @@
       gap: 0.5rem 1rem;
       grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
     }
-    table {
-      width: 100%;
-      border-collapse: collapse;
-      font-size: 0.85rem;
-      margin-top: 0.75rem;
-    }
-    th, td {
-      text-align: left;
-      padding: 0.5rem 0.25rem;
-      border-bottom: 1px solid var(--border);
-      vertical-align: middle;
-    }
-    th { color: var(--muted); font-weight: 500; font-size: 0.75rem; }
-    .empty { color: var(--muted); font-size: 0.85rem; margin-top: 0.5rem; }
-    .msg-err { color: var(--err); font-size: 0.85rem; margin-top: 0.5rem; }
-    .msg-ok { color: var(--ok); font-size: 0.85rem; margin-top: 0.5rem; }
-    .item-grid {
-      display: grid;
-      gap: 1rem;
-      grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
-      margin-top: 1rem;
-    }
-    .item-card {
+    .msg-err { color: var(--err); font-size: 0.85rem; margin-top: 0.75rem; }
+    .msg-ok { color: var(--ok); font-size: 0.85rem; margin-top: 0.75rem; }
+    .item-preview-panel {
+      margin-bottom: 1.25rem;
       background: var(--bg);
       border: 1px solid var(--border);
       border-radius: 8px;
-      overflow: hidden;
-      display: flex;
-      flex-direction: column;
-    }
-    .item-preview {
-      background: #fff;
-      padding: 0.75rem;
+      padding: 1rem;
       display: flex;
       align-items: center;
       justify-content: center;
-      min-height: 160px;
+      min-height: 180px;
     }
-    .item-preview img {
+    .item-preview-panel img {
       max-width: 100%;
-      max-height: 140px;
-      width: auto;
-      height: auto;
+      max-height: 160px;
+      background: #fff;
+      padding: 0.5rem;
+      border-radius: 4px;
     }
-    .item-body {
-      padding: 0.75rem;
-      flex: 1;
-      display: flex;
-      flex-direction: column;
-      gap: 0.35rem;
-    }
-    .item-body strong { font-size: 0.9rem; }
-    .item-body span { font-size: 0.8rem; color: var(--muted); }
-    .item-actions {
-      padding: 0 0.75rem 0.75rem;
-    }
-    .row-actions { display: flex; gap: 0.5rem; justify-content: flex-end; }
     .layout-preview-wrap {
-      margin-top: 1rem;
+      margin-top: 1.25rem;
       background: var(--bg);
       border: 1px solid var(--border);
       border-radius: 8px;
@@ -181,301 +239,285 @@
     }
     .layout-stats strong { color: var(--text); }
     .layout-stats span { color: var(--muted); }
-    select {
-      width: 100%;
-      margin-top: 0.5rem;
-      padding: 0.5rem 0.75rem;
-      background: var(--bg);
-      border: 1px solid var(--border);
-      border-radius: 6px;
-      color: var(--text);
-      font-size: 0.875rem;
-    }
-    .config-list {
-      display: grid;
-      gap: 1rem;
-      margin-top: 1rem;
-    }
-    .config-entry {
-      background: var(--bg);
-      border: 1px solid var(--border);
-      border-radius: 8px;
-      padding: 1rem;
-    }
-    .config-entry header {
-      display: flex;
-      justify-content: space-between;
-      align-items: flex-start;
-      gap: 1rem;
-      margin-bottom: 0;
-      padding-bottom: 0.5rem;
-      border-bottom: none;
-    }
-    .config-entry header h3 {
+    .empty-state {
+      color: var(--muted);
       font-size: 0.95rem;
-      font-weight: 600;
+      padding: 2rem 0;
+      text-align: center;
+    }
+    @media (max-width: 720px) {
+      .app { flex-direction: column; }
+      .sidebar {
+        width: 100%;
+        height: auto;
+        position: relative;
+        max-height: 45vh;
+      }
+      .main { padding: 1.25rem; }
     }
   </style>
 </head>
 <body>
-  <div class="page" x-data="dashboard()" x-init="init()">
-    <header>
-      <h1>Printer Backend</h1>
-      <p>Platten und Items verwalten</p>
-    </header>
+  <div class="app" x-data="dashboard()" x-init="init()">
+    <aside class="sidebar">
+      <div class="sidebar-brand">
+        <h1>Printer Backend</h1>
+        <p>Admin</p>
+      </div>
 
-    <div class="grid">
-      <section class="card">
-        <h2>API</h2>
-        <label for="api-base">Basis-URL</label>
-        <input id="api-base" type="url" x-model="apiBase" @change="onApiBaseChange()" placeholder="http://127.0.0.1:8080">
-        <p class="muted" x-show="apiOk === true">API erreichbar</p>
-        <p class="msg-err" x-show="apiOk === false">API nicht erreichbar</p>
-      </section>
-
-      <section class="card wide">
-        <h2 x-text="plateEditingId ? 'Platte bearbeiten' : 'Platte anlegen'"></h2>
-        <form @submit.prevent="savePlate()">
-          <div class="form-grid">
-            <div>
-              <label>Name (optional)</label>
-              <input type="text" x-model="plateForm.name" placeholder="z.B. Druckbett A3">
-            </div>
-            <div>
-              <label>Breite (mm)</label>
-              <input type="number" step="0.1" min="0" x-model.number="plateForm.width_mm" required>
-            </div>
-            <div>
-              <label>Höhe (mm)</label>
-              <input type="number" step="0.1" min="0" x-model.number="plateForm.height_mm" required>
-            </div>
-            <div>
-              <label>Margin oben</label>
-              <input type="number" step="0.1" min="0" x-model.number="plateForm.margin_top_mm">
-            </div>
-            <div>
-              <label>Margin rechts</label>
-              <input type="number" step="0.1" min="0" x-model.number="plateForm.margin_right_mm">
-            </div>
-            <div>
-              <label>Margin unten</label>
-              <input type="number" step="0.1" min="0" x-model.number="plateForm.margin_bottom_mm">
-            </div>
-            <div>
-              <label>Margin links</label>
-              <input type="number" step="0.1" min="0" x-model.number="plateForm.margin_left_mm">
-            </div>
-          </div>
-          <div class="btn-row">
-            <button type="submit" :disabled="plateSaving">
-              <span x-text="plateSaving ? 'Speichere…' : (plateEditingId ? 'Änderungen speichern' : 'Platte anlegen')"></span>
-            </button>
-            <button type="button" class="secondary" x-show="plateEditingId" @click="cancelPlateEdit()">Abbrechen</button>
-          </div>
-          <p class="msg-err" x-show="plateError" x-text="plateError"></p>
-          <p class="msg-ok" x-show="plateSuccess" x-text="plateSuccess"></p>
-        </form>
-      </section>
-
-      <section class="card wide">
-        <h2>Platten</h2>
-        <template x-if="plates.length === 0 && !platesLoading">
-          <p class="empty">Keine Platten.</p>
-        </template>
-        <table x-show="plates.length > 0">
-          <thead>
-            <tr>
-              <th>Name</th>
-              <th>Größe</th>
-              <th>Margins</th>
-              <th>Druckfläche</th>
-              <th></th>
-            </tr>
-          </thead>
-          <tbody>
-            <template x-for="p in plates" :key="p.id">
-              <tr>
-                <td x-text="p.name || '—'"></td>
-                <td x-text="fmtSize(p.width_mm, p.height_mm)"></td>
-                <td x-text="fmtMargins(p)"></td>
-                <td x-text="fmtPrintable(p)"></td>
-                <td class="row-actions">
-                  <button type="button" class="secondary" @click="editPlate(p)">Bearbeiten</button>
-                  <button type="button" class="danger" @click="deletePlate(p.id)">Löschen</button>
-                </td>
-              </tr>
+      <nav class="sidebar-nav">
+        <div class="nav-section">
+          <button type="button" class="nav-section-header"
+            :class="{ active: section === 'plates' }"
+            @click="openSection('plates')">
+            Platten
+            <span class="nav-chevron" :class="{ open: expanded.plates }"></span>
+          </button>
+          <div class="nav-children" x-show="expanded.plates">
+            <template x-if="plates.length === 0 && !platesLoading">
+              <p class="nav-empty">Keine Platten</p>
             </template>
-          </tbody>
-        </table>
-      </section>
-
-      <section class="card wide">
-        <h2 x-text="itemEditingId ? 'Item bearbeiten' : 'Item anlegen'"></h2>
-        <p class="muted" x-show="!itemEditingId">Erzeugt SVG-Maske in <code>data/svg_template/</code>.</p>
-        <p class="muted" x-show="itemEditingId">Aktualisiert SVG und Metadaten; Dateiname bleibt unverändert.</p>
-        <form @submit.prevent="saveItem()">
-          <div class="form-grid">
-            <div>
-              <label>Name</label>
-              <input type="text" x-model="itemForm.name" placeholder="z.B. sticker_80" :required="!itemEditingId">
-            </div>
-            <div>
-              <label>Breite (mm)</label>
-              <input type="number" step="0.1" min="0" x-model.number="itemForm.width_mm" required>
-            </div>
-            <div>
-              <label>Höhe (mm)</label>
-              <input type="number" step="0.1" min="0" x-model.number="itemForm.height_mm" required>
-            </div>
-            <div>
-              <label>Eckenradius (mm)</label>
-              <input type="number" step="0.1" min="0" x-model.number="itemForm.corner_radius_mm">
-            </div>
-            <div>
-              <label>Bleed (mm)</label>
-              <input type="number" step="0.1" min="0" x-model.number="itemForm.bleed_mm">
-            </div>
-            <div>
-              <label>Margin (mm)</label>
-              <input type="number" step="0.1" min="0" x-model.number="itemForm.margin_mm">
-            </div>
-            <div>
-              <label>Padding (mm)</label>
-              <input type="number" step="0.1" min="0" x-model.number="itemForm.padding_mm">
-            </div>
+            <template x-for="p in plates" :key="p.id">
+              <button type="button" class="nav-item"
+                :class="{ selected: section === 'plates' && plateEditingId === p.id }"
+                @click="selectPlate(p)"
+                x-text="sidebarPlateLabel(p)"></button>
+            </template>
+            <button type="button" class="nav-item add"
+              :class="{ selected: section === 'plates' && !plateEditingId }"
+              @click="newPlate()">+ Neu</button>
           </div>
-          <div class="btn-row">
-            <button type="submit" :disabled="itemSaving">
-              <span x-text="itemSaving ? 'Speichere…' : (itemEditingId ? 'Änderungen speichern' : 'Item anlegen')"></span>
-            </button>
-            <button type="button" class="secondary" x-show="itemEditingId" @click="cancelItemEdit()">Abbrechen</button>
-          </div>
-          <p class="msg-err" x-show="itemError" x-text="itemError"></p>
-          <p class="msg-ok" x-show="itemSuccess" x-text="itemSuccess"></p>
-        </form>
-      </section>
-
-      <section class="card wide">
-        <h2 x-text="configEditingId ? 'Konfiguration bearbeiten' : 'Konfiguration — Layout-Vorschau'"></h2>
-        <p class="muted">Kombiniert Platte und Item; berechnet maximale Stückzahl unter Einhaltung aller Margins und Abstände.</p>
-        <form @submit.prevent="saveConfiguration()">
-          <div class="form-grid">
-            <div>
-              <label>Name (optional)</label>
-              <input type="text" x-model="configForm.name" placeholder="z.B. A3 × Sticker 80">
-            </div>
-            <div>
-              <label>Platte</label>
-              <select x-model="configForm.plate_id" @change="refreshLayoutPreview()" required>
-                <option value="">— wählen —</option>
-                <template x-for="p in plates" :key="p.id">
-                  <option :value="p.id" x-text="labelPlate(p)"></option>
-                </template>
-              </select>
-            </div>
-            <div>
-              <label>Item</label>
-              <select x-model="configForm.item_id" @change="refreshLayoutPreview()" required>
-                <option value="">— wählen —</option>
-                <template x-for="it in items" :key="it.id">
-                  <option :value="it.id" x-text="labelItem(it)"></option>
-                </template>
-              </select>
-            </div>
-            <div>
-              <label>Abstand zwischen Items (mm)</label>
-              <input type="number" step="0.1" min="0" x-model.number="configForm.spacing_mm" @input="refreshLayoutPreview()">
-            </div>
-          </div>
-          <div class="btn-row">
-            <button type="submit" :disabled="configSaving || !configForm.plate_id || !configForm.item_id">
-              <span x-text="configSaving ? 'Speichere…' : (configEditingId ? 'Änderungen speichern' : 'Konfiguration speichern')"></span>
-            </button>
-            <button type="button" class="secondary" x-show="configEditingId" @click="cancelConfigEdit()">Abbrechen</button>
-            <button type="button" class="secondary" @click="downloadLayoutPDF()"
-              :disabled="pdfGenerating || !layoutPreview || !configForm.plate_id || !configForm.item_id">
-              <span x-text="pdfGenerating ? 'PDF…' : 'PDF-Vorschau'"></span>
-            </button>
-          </div>
-          <p class="msg-err" x-show="configError" x-text="configError"></p>
-          <p class="msg-ok" x-show="configSuccess" x-text="configSuccess"></p>
-        </form>
-
-        <template x-if="layoutPreview">
-          <div class="layout-preview-wrap">
-            <div x-html="layoutPreviewSvg()"></div>
-            <div class="layout-stats">
-              <span><strong x-text="layoutPreview.count"></strong> Items passen</span>
-              <span><strong x-text="layoutPreview.columns + ' × ' + layoutPreview.rows"></strong> Raster</span>
-              <span>Item <strong x-text="layoutPreview.footprint_width_mm.toFixed(1) + ' × ' + layoutPreview.footprint_height_mm.toFixed(1) + ' mm'"></strong></span>
-              <span>Zellenabstand <strong x-text="layoutPreview.cell_width_mm.toFixed(1) + ' mm'"></strong></span>
-              <span>Druckfläche <strong x-text="layoutPreview.printable_width_mm.toFixed(1) + ' × ' + layoutPreview.printable_height_mm.toFixed(1) + ' mm'"></strong></span>
-            </div>
-          </div>
-        </template>
-        <p class="empty" x-show="!layoutPreview && configForm.plate_id && configForm.item_id && !layoutLoading">
-          Keine Vorschau (Platte zu klein oder API-Fehler).
-        </p>
-        <p class="muted" x-show="layoutLoading">Berechne Layout…</p>
-      </section>
-
-      <section class="card wide" x-show="configurations.length > 0">
-        <h2>Gespeicherte Konfigurationen</h2>
-        <div class="config-list">
-          <template x-for="c in configurations" :key="c.id">
-            <article class="config-entry">
-              <header>
-                <div>
-                  <h3 x-text="c.name || ('Konfiguration ' + c.id.slice(0, 8))"></h3>
-                  <p class="muted" x-text="configSummary(c)"></p>
-                </div>
-                <div class="row-actions">
-                  <button type="button" class="secondary" @click="editConfiguration(c)">Bearbeiten</button>
-                  <button type="button" class="secondary" @click="downloadConfigurationPDF(c.id)"
-                    :disabled="pdfGenerating || !!c.preview_error" x-show="c.preview && !c.preview_error">
-                    PDF
-                  </button>
-                  <button type="button" class="danger" @click="deleteConfiguration(c.id)">Löschen</button>
-                </div>
-              </header>
-              <p class="msg-err" x-show="c.preview_error" x-text="c.preview_error"></p>
-              <div class="layout-preview-wrap" x-show="c.preview && !c.preview_error">
-                <div x-html="layoutPreviewSvg(c.preview)"></div>
-                <div class="layout-stats">
-                  <span><strong x-text="c.preview.count"></strong> Items</span>
-                  <span><strong x-text="c.preview.columns + ' × ' + c.preview.rows"></strong></span>
-                </div>
-              </div>
-            </article>
-          </template>
         </div>
-      </section>
 
-      <section class="card wide">
-        <h2>Items</h2>
-        <template x-if="items.length === 0 && !itemsLoading">
-          <p class="empty">Keine Items.</p>
-        </template>
-        <div class="item-grid" x-show="items.length > 0">
-          <template x-for="it in items" :key="it.id">
-            <article class="item-card">
-              <div class="item-preview">
-                <img :src="itemSvgUrl(it.id)" :alt="labelItem(it)" loading="lazy">
-              </div>
-              <div class="item-body">
-                <strong x-text="labelItem(it)"></strong>
-                <span x-text="itemSizeLabel(it)"></span>
-                <span><code x-text="it.svg_template"></code></span>
-              </div>
-              <div class="item-actions row-actions">
-                <button type="button" class="secondary" @click="editItem(it)">Bearbeiten</button>
-                <button type="button" class="danger" @click="deleteItem(it.id)">Löschen</button>
-              </div>
-            </article>
-          </template>
+        <div class="nav-section">
+          <button type="button" class="nav-section-header"
+            :class="{ active: section === 'items' }"
+            @click="openSection('items')">
+            Items
+            <span class="nav-chevron" :class="{ open: expanded.items }"></span>
+          </button>
+          <div class="nav-children" x-show="expanded.items">
+            <template x-if="items.length === 0 && !itemsLoading">
+              <p class="nav-empty">Keine Items</p>
+            </template>
+            <template x-for="it in items" :key="it.id">
+              <button type="button" class="nav-item"
+                :class="{ selected: section === 'items' && itemEditingId === it.id }"
+                @click="selectItem(it)"
+                x-text="labelItem(it)"></button>
+            </template>
+            <button type="button" class="nav-item add"
+              :class="{ selected: section === 'items' && !itemEditingId }"
+              @click="newItem()">+ Neu</button>
+          </div>
         </div>
-      </section>
-    </div>
+
+        <div class="nav-section">
+          <button type="button" class="nav-section-header"
+            :class="{ active: section === 'configurations' }"
+            @click="openSection('configurations')">
+            Konfigurationen
+            <span class="nav-chevron" :class="{ open: expanded.configurations }"></span>
+          </button>
+          <div class="nav-children" x-show="expanded.configurations">
+            <template x-if="configurations.length === 0">
+              <p class="nav-empty">Keine Konfigurationen</p>
+            </template>
+            <template x-for="c in configurations" :key="c.id">
+              <button type="button" class="nav-item"
+                :class="{ selected: section === 'configurations' && configEditingId === c.id }"
+                @click="selectConfiguration(c)"
+                x-text="sidebarConfigLabel(c)"></button>
+            </template>
+            <button type="button" class="nav-item add"
+              :class="{ selected: section === 'configurations' && !configEditingId }"
+              @click="newConfiguration()">+ Neu</button>
+          </div>
+        </div>
+      </nav>
+
+      <div class="sidebar-footer">
+        <label for="api-base">API</label>
+        <input id="api-base" type="url" x-model="apiBase" @change="onApiBaseChange()" placeholder="http://127.0.0.1:8080">
+        <p class="api-status ok" x-show="apiOk === true">Erreichbar</p>
+        <p class="api-status err" x-show="apiOk === false">Nicht erreichbar</p>
+      </div>
+    </aside>
+
+    <main class="main">
+      <!-- Platten -->
+      <div x-show="section === 'plates'">
+        <div class="main-header">
+          <h2 x-text="plateEditingId ? 'Platte bearbeiten' : 'Neue Platte'"></h2>
+          <p class="muted" x-show="!plateEditingId">Druckbett mit Abmessungen und Rändern anlegen.</p>
+        </div>
+        <div class="panel">
+          <form @submit.prevent="savePlate()">
+            <div class="form-grid">
+              <div>
+                <label>Name (optional)</label>
+                <input type="text" x-model="plateForm.name" placeholder="z.B. Druckbett A3">
+              </div>
+              <div>
+                <label>Breite (mm)</label>
+                <input type="number" step="0.1" min="0" x-model.number="plateForm.width_mm" required>
+              </div>
+              <div>
+                <label>Höhe (mm)</label>
+                <input type="number" step="0.1" min="0" x-model.number="plateForm.height_mm" required>
+              </div>
+              <div>
+                <label>Margin oben</label>
+                <input type="number" step="0.1" min="0" x-model.number="plateForm.margin_top_mm">
+              </div>
+              <div>
+                <label>Margin rechts</label>
+                <input type="number" step="0.1" min="0" x-model.number="plateForm.margin_right_mm">
+              </div>
+              <div>
+                <label>Margin unten</label>
+                <input type="number" step="0.1" min="0" x-model.number="plateForm.margin_bottom_mm">
+              </div>
+              <div>
+                <label>Margin links</label>
+                <input type="number" step="0.1" min="0" x-model.number="plateForm.margin_left_mm">
+              </div>
+            </div>
+            <div class="btn-row">
+              <button type="submit" :disabled="plateSaving">
+                <span x-text="plateSaving ? 'Speichere…' : (plateEditingId ? 'Speichern' : 'Anlegen')"></span>
+              </button>
+              <button type="button" class="danger" x-show="plateEditingId" @click="deletePlate(plateEditingId)">Löschen</button>
+            </div>
+            <p class="msg-err" x-show="plateError" x-text="plateError"></p>
+            <p class="msg-ok" x-show="plateSuccess" x-text="plateSuccess"></p>
+          </form>
+        </div>
+      </div>
+
+      <!-- Items -->
+      <div x-show="section === 'items'">
+        <div class="main-header">
+          <h2 x-text="itemEditingId ? 'Item bearbeiten' : 'Neues Item'"></h2>
+          <p class="muted" x-show="!itemEditingId">Erzeugt SVG-Maske in <code>data/svg_template/</code>.</p>
+          <p class="muted" x-show="itemEditingId">SVG und Metadaten aktualisieren; Dateiname bleibt unverändert.</p>
+        </div>
+        <div class="panel">
+          <div class="item-preview-panel" x-show="itemEditingId">
+            <img :src="itemSvgUrl(itemEditingId)" alt="SVG-Vorschau" loading="lazy">
+          </div>
+          <form @submit.prevent="saveItem()">
+            <div class="form-grid">
+              <div>
+                <label>Name</label>
+                <input type="text" x-model="itemForm.name" placeholder="z.B. sticker_80" :required="!itemEditingId">
+              </div>
+              <div>
+                <label>Breite (mm)</label>
+                <input type="number" step="0.1" min="0" x-model.number="itemForm.width_mm" required>
+              </div>
+              <div>
+                <label>Höhe (mm)</label>
+                <input type="number" step="0.1" min="0" x-model.number="itemForm.height_mm" required>
+              </div>
+              <div>
+                <label>Eckenradius (mm)</label>
+                <input type="number" step="0.1" min="0" x-model.number="itemForm.corner_radius_mm">
+              </div>
+              <div>
+                <label>Bleed (mm)</label>
+                <input type="number" step="0.1" min="0" x-model.number="itemForm.bleed_mm">
+              </div>
+              <div>
+                <label>Margin (mm)</label>
+                <input type="number" step="0.1" min="0" x-model.number="itemForm.margin_mm">
+              </div>
+              <div>
+                <label>Padding (mm)</label>
+                <input type="number" step="0.1" min="0" x-model.number="itemForm.padding_mm">
+              </div>
+            </div>
+            <div class="btn-row">
+              <button type="submit" :disabled="itemSaving">
+                <span x-text="itemSaving ? 'Speichere…' : (itemEditingId ? 'Speichern' : 'Anlegen')"></span>
+              </button>
+              <button type="button" class="danger" x-show="itemEditingId" @click="deleteItem(itemEditingId)">Löschen</button>
+            </div>
+            <p class="msg-err" x-show="itemError" x-text="itemError"></p>
+            <p class="msg-ok" x-show="itemSuccess" x-text="itemSuccess"></p>
+          </form>
+        </div>
+      </div>
+
+      <!-- Konfigurationen -->
+      <div x-show="section === 'configurations'">
+        <div class="main-header">
+          <h2 x-text="configEditingId ? 'Konfiguration bearbeiten' : 'Neue Konfiguration'"></h2>
+          <p class="muted">Kombiniert Platte und Item; berechnet maximale Stückzahl.</p>
+        </div>
+        <div class="panel">
+          <form @submit.prevent="saveConfiguration()">
+            <div class="form-grid">
+              <div>
+                <label>Name (optional)</label>
+                <input type="text" x-model="configForm.name" placeholder="z.B. A3 × Sticker 80">
+              </div>
+              <div>
+                <label>Platte</label>
+                <select x-model="configForm.plate_id" @change="refreshLayoutPreview()" required>
+                  <option value="">— wählen —</option>
+                  <template x-for="p in plates" :key="p.id">
+                    <option :value="p.id" x-text="labelPlate(p)"></option>
+                  </template>
+                </select>
+              </div>
+              <div>
+                <label>Item</label>
+                <select x-model="configForm.item_id" @change="refreshLayoutPreview()" required>
+                  <option value="">— wählen —</option>
+                  <template x-for="it in items" :key="it.id">
+                    <option :value="it.id" x-text="labelItem(it)"></option>
+                  </template>
+                </select>
+              </div>
+              <div>
+                <label>Abstand zwischen Items (mm)</label>
+                <input type="number" step="0.1" min="0" x-model.number="configForm.spacing_mm" @input="refreshLayoutPreview()">
+              </div>
+            </div>
+            <div class="btn-row">
+              <button type="submit" :disabled="configSaving || !configForm.plate_id || !configForm.item_id">
+                <span x-text="configSaving ? 'Speichere…' : (configEditingId ? 'Speichern' : 'Anlegen')"></span>
+              </button>
+              <button type="button" class="secondary" @click="downloadLayoutPDF()"
+                :disabled="pdfGenerating || !layoutPreview || !configForm.plate_id || !configForm.item_id">
+                <span x-text="pdfGenerating ? 'PDF…' : 'PDF-Vorschau'"></span>
+              </button>
+              <button type="button" class="danger" x-show="configEditingId" @click="deleteConfiguration(configEditingId)">Löschen</button>
+            </div>
+            <p class="msg-err" x-show="configError" x-text="configError"></p>
+            <p class="msg-ok" x-show="configSuccess" x-text="configSuccess"></p>
+          </form>
+
+          <template x-if="layoutPreview">
+            <div class="layout-preview-wrap">
+              <div x-html="layoutPreviewSvg()"></div>
+              <div class="layout-stats">
+                <span><strong x-text="layoutPreview.count"></strong> Items passen</span>
+                <span><strong x-text="layoutPreview.columns + ' × ' + layoutPreview.rows"></strong> Raster</span>
+                <span>Item <strong x-text="layoutPreview.footprint_width_mm.toFixed(1) + ' × ' + layoutPreview.footprint_height_mm.toFixed(1) + ' mm'"></strong></span>
+                <span>Zellenabstand <strong x-text="layoutPreview.cell_width_mm.toFixed(1) + ' mm'"></strong></span>
+                <span>Druckfläche <strong x-text="layoutPreview.printable_width_mm.toFixed(1) + ' × ' + layoutPreview.printable_height_mm.toFixed(1) + ' mm'"></strong></span>
+              </div>
+            </div>
+          </template>
+          <p class="muted" x-show="!layoutPreview && configForm.plate_id && configForm.item_id && !layoutLoading">
+            Keine Vorschau (Platte zu klein oder API-Fehler).
+          </p>
+          <p class="muted" x-show="layoutLoading">Berechne Layout…</p>
+        </div>
+      </div>
+    </main>
   </div>
 
   <script>
@@ -484,6 +526,9 @@
         apiBase: '',
         apiOk: null,
 
+        section: 'plates',
+        expanded: { plates: true, items: false, configurations: false },
+
         plates: [],
         platesLoading: false,
         plateSaving: false,
@@ -532,6 +577,60 @@
         pdfGenerating: false,
         _layoutTimer: null,
 
+        openSection(name) {
+          if (this.section === name) {
+            this.expanded[name] = !this.expanded[name];
+          } else {
+            this.section = name;
+            this.expanded[name] = true;
+          }
+        },
+
+        selectPlate(p) {
+          this.section = 'plates';
+          this.expanded.plates = true;
+          this.editPlate(p);
+        },
+
+        newPlate() {
+          this.section = 'plates';
+          this.expanded.plates = true;
+          this.cancelPlateEdit();
+        },
+
+        selectItem(it) {
+          this.section = 'items';
+          this.expanded.items = true;
+          this.editItem(it);
+        },
+
+        newItem() {
+          this.section = 'items';
+          this.expanded.items = true;
+          this.cancelItemEdit();
+        },
+
+        selectConfiguration(c) {
+          this.section = 'configurations';
+          this.expanded.configurations = true;
+          this.editConfiguration(c);
+        },
+
+        newConfiguration() {
+          this.section = 'configurations';
+          this.expanded.configurations = true;
+          this.cancelConfigEdit();
+        },
+
+        sidebarPlateLabel(p) {
+          const n = p.name || 'Platte';
+          return n + ' · ' + this.fmtSize(p.width_mm, p.height_mm);
+        },
+
+        sidebarConfigLabel(c) {
+          return c.name || ('Konfiguration ' + c.id.slice(0, 8));
+        },
+
         apiUrl(path) {
           return `${this.apiBase.replace(/\/$/, '')}${path}`;
         },
@@ -655,8 +754,15 @@
               await this.apiJSON('POST', '/plates', body);
               this.plateSuccess = 'Platte gespeichert.';
             }
-            this.cancelPlateEdit();
+            const keepId = this.plateEditingId;
             await this.loadPlates();
+            if (keepId) {
+              const p = this.plates.find(x => x.id === keepId);
+              if (p) this.editPlate(p);
+              else this.cancelPlateEdit();
+            } else {
+              this.cancelPlateEdit();
+            }
             this.refreshLayoutPreview();
           } catch (e) {
             this.plateError = String(e.message || e);
@@ -799,8 +905,15 @@
               await this.apiJSON('POST', '/items', body);
               this.itemSuccess = 'Item erzeugt.';
             }
-            this.cancelItemEdit();
+            const keepId = this.itemEditingId;
             await this.loadItems();
+            if (keepId) {
+              const it = this.items.find(x => x.id === keepId);
+              if (it) this.editItem(it);
+              else this.cancelItemEdit();
+            } else {
+              this.cancelItemEdit();
+            }
             this.refreshLayoutPreview();
           } catch (e) {
             this.itemError = String(e.message || e);
@@ -885,8 +998,15 @@
               await this.apiJSON('POST', '/configurations', body);
               this.configSuccess = 'Konfiguration gespeichert.';
             }
-            this.cancelConfigEdit();
+            const keepId = this.configEditingId;
             await this.loadConfigurations();
+            if (keepId) {
+              const c = this.configurations.find(x => x.id === keepId);
+              if (c) this.editConfiguration(c);
+              else this.cancelConfigEdit();
+            } else {
+              this.cancelConfigEdit();
+            }
           } catch (e) {
             this.configError = String(e.message || e);
           } finally {
@@ -927,11 +1047,13 @@
             item_id: this.configForm.item_id,
             spacing_mm: String(Number(this.configForm.spacing_mm) || 0),
           });
-          this.downloadBlob('/layout/pdf?' + q, 'layout-preview.pdf');
-        },
-
-        downloadConfigurationPDF(id) {
-          this.downloadBlob('/configurations/' + id + '/pdf', 'configuration-' + id.slice(0, 8) + '.pdf');
+          const name = this.configEditingId
+            ? 'configuration-' + this.configEditingId.slice(0, 8) + '.pdf'
+            : 'layout-preview.pdf';
+          const path = this.configEditingId
+            ? '/configurations/' + this.configEditingId + '/pdf'
+            : '/layout/pdf?' + q;
+          this.downloadBlob(path, name);
         },
 
         async deleteConfiguration(id) {