diff --git a/spike_visualizer/css/base.css b/spike_visualizer/css/base.css
new file mode 100644
index 0000000..8d3b419
--- /dev/null
+++ b/spike_visualizer/css/base.css
@@ -0,0 +1,75 @@
+/* =============================================
+   CSS Reset & Variablen
+   ============================================= */
+
+:root {
+  --color-bg: #f9f9fb;
+  --color-text: #222;
+  --color-accent: #0050b3;
+  --color-border: #ddd;
+  --font-base: 'Segoe UI', Arial, sans-serif;
+  --font-size-base: 16px;
+  --spacing-unit: 8px;
+  --max-content-width: 1200px;
+}
+
+html {
+  box-sizing: border-box;
+  font-size: var(--font-size-base);
+}
+
+*, *::before, *::after {
+  box-sizing: inherit;
+  margin: 0;
+  padding: 0;
+}
+
+body {
+  line-height: 1.5;
+  background-color: var(--color-bg);
+  color: var(--color-text);
+  font-family: var(--font-base);
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+/* =============================================
+   Grundlayout
+   ============================================= */
+
+.app-shell {
+  display: flex;
+  flex-direction: column;
+  min-height: 100vh;
+}
+
+.app-header {
+  flex: 0 0 auto;
+  background-color: var(--color-accent);
+  color: #fff;
+  padding: calc(var(--spacing-unit) * 2);
+  text-align: center;
+}
+
+.app-main {
+  flex: 1 1 auto;
+  padding: calc(var(--spacing-unit) * 2);
+  max-width: var(--max-content-width);
+  margin: 0 auto;
+  width: 100%;
+}
+
+.app-footer {
+  flex: 0 0 auto;
+  border-top: 1px solid var(--color-border);
+  text-align: center;
+  padding: calc(var(--spacing-unit) * 1.5);
+  font-size: 0.875rem;
+  color: #666;
+}
+
+.app-footer::after {
+  content: "© 2026 Donau2Space.de";
+  display: block;
+  margin-top: var(--spacing-unit);
+}