diff --git a/max_outlier_visualization/css/base.css b/max_outlier_visualization/css/base.css
new file mode 100644
index 0000000..7d61abc
--- /dev/null
+++ b/max_outlier_visualization/css/base.css
@@ -0,0 +1,148 @@
+/* ======================================
+   CSS Reset & Variables
+   ====================================== */
+
+:root {
+  /* Color Palette */
+  --color-bg: #f9fafb;
+  --color-surface: #ffffff;
+  --color-border: #d1d5db;
+  --color-text: #111827;
+  --color-accent: #2563eb;
+  --color-accent-hover: #1e40af;
+
+  /* Spacing */
+  --spacing-xs: 0.25rem;
+  --spacing-sm: 0.5rem;
+  --spacing-md: 1rem;
+  --spacing-lg: 2rem;
+  --spacing-xl: 4rem;
+
+  /* Typography */
+  --font-family-base: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
+  --font-size-base: 16px;
+  --line-height-base: 1.5;
+
+  /* Layout */
+  --max-width-content: 1200px;
+  --transition-base: 0.2s ease-in-out;
+
+  /* Breakpoints */
+  --bp-sm: 640px;
+  --bp-md: 768px;
+  --bp-lg: 1024px;
+  --bp-xl: 1280px;
+}
+
+/* Reset Styles */
+* {
+  margin: 0;
+  padding: 0;
+  box-sizing: border-box;
+}
+
+html, body {
+  width: 100%;
+  height: 100%;
+}
+
+body {
+  font-family: var(--font-family-base);
+  font-size: var(--font-size-base);
+  line-height: var(--line-height-base);
+  background-color: var(--color-bg);
+  color: var(--color-text);
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+h1, h2, h3, h4, h5, h6 {
+  font-weight: 600;
+  line-height: 1.25;
+  color: var(--color-text);
+}
+
+a {
+  color: var(--color-accent);
+  text-decoration: none;
+  transition: color var(--transition-base);
+}
+
+a:hover, a:focus {
+  color: var(--color-accent-hover);
+}
+
+ul, ol {
+  list-style: none;
+}
+
+button {
+  background: none;
+  border: none;
+  cursor: pointer;
+  font: inherit;
+  color: inherit;
+}
+
+/* ======================================
+   Application Shell Layout
+   ====================================== */
+
+.app-shell {
+  display: flex;
+  flex-direction: column;
+  min-height: 100vh;
+}
+
+.app-header {
+  background-color: var(--color-surface);
+  border-bottom: 1px solid var(--color-border);
+  padding: var(--spacing-md);
+  text-align: center;
+}
+
+.app-header h1 {
+  font-size: 1.5rem;
+  margin-bottom: var(--spacing-sm);
+}
+
+main {
+  flex: 1;
+  max-width: var(--max-width-content);
+  margin: 0 auto;
+  padding: var(--spacing-lg) var(--spacing-md);
+  width: 100%;
+}
+
+.app-footer {
+  background-color: var(--color-surface);
+  border-top: 1px solid var(--color-border);
+  text-align: center;
+  padding: var(--spacing-sm);
+  font-size: 0.875rem;
+}
+
+.app-footer p {
+  color: var(--color-text);
+  opacity: 0.8;
+}
+
+/* Responsive typography and spacing */
+@media (min-width: 640px) {
+  .app-header h1 {
+    font-size: 2rem;
+  }
+  main {
+    padding: var(--spacing-xl) var(--spacing-lg);
+  }
+}
+
+/* Footer copyright */
+.app-footer::after {
+  content: "© 2026 Donau2Space.de";
+  display: block;
+  margin-top: var(--spacing-xs);
+  font-size: 0.75rem;
+  color: var(--color-text);
+  opacity: 0.6;
+}
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