diff --git a/data_visualization/css/base.css b/data_visualization/css/base.css
new file mode 100644
index 0000000..e1d7bea
--- /dev/null
+++ b/data_visualization/css/base.css
@@ -0,0 +1,69 @@
+:root {
+  --color-bg: #ffffff;
+  --color-text: #222222;
+  --color-accent: #007acc;
+  --color-border: #dddddd;
+  --font-base: 'Segoe UI', Tahoma, sans-serif;
+  --space-unit: 1rem;
+}
+
+body {
+  margin: 0;
+  padding: 0;
+  font-family: var(--font-base);
+  color: var(--color-text);
+  background-color: var(--color-bg);
+  line-height: 1.6;
+}
+
+h1, h2, p {
+  margin: 0 0 var(--space-unit) 0;
+  padding: 0;
+}
+
+h1 {
+  font-size: 1.8rem;
+  font-weight: 600;
+  color: var(--color-accent);
+}
+
+h2 {
+  font-size: 1.4rem;
+  font-weight: 500;
+}
+
+p {
+  font-size: 1rem;
+}
+
+.app-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  padding: var(--space-unit);
+  border-bottom: 1px solid var(--color-border);
+  background-color: #f5f5f5;
+}
+
+.app-footer {
+  text-align: center;
+  padding: var(--space-unit);
+  border-top: 1px solid var(--color-border);
+  font-size: 0.9rem;
+}
+
+.chart-area {
+  display: flex;
+  flex-direction: column;
+  align-items: stretch;
+  padding: var(--space-unit);
+  flex: 1;
+}
+
+.filter-panel {
+  display: flex;
+  gap: calc(var(--space-unit) / 2);
+  padding: var(--space-unit);
+  background-color: #fafafa;
+  border-bottom: 1px solid var(--color-border);
+}
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