added streamlit theme

.gitignore

@@ -1,4 +1,5 @@
 .*
 !.gitignore
+!.streamlit
 data/spectra
 data/meta/metadata.json

.streamlit/config.toml

@@ -0,0 +1,18 @@
+[theme]
+
+# Primary accent for interactive elements
+primaryColor = '#6eb52f'
+
+# Background color for the main content area
+backgroundColor = '#f0f0f5'
+
+# Background color for sidebar and most interactive widgets
+secondaryBackgroundColor = '#e0e0ef'
+
+# Color used for almost all text
+textColor = '#262730'
+
+# Font family for all text in the app, except code blocks
+# Accepted values (serif | sans serif | monospace) 
+# Default: "sans serif"
+font = "sans serif"