Add app theme and keep popup in map view

[JeremyLoh]

Light Mode Color Scheme - https://www.realtimecolors.com/?colors=070b03-f9fcf5-99cb3f-9ae4e1-5f98d4&fonts=Ubuntu-Ubuntu

Dark Mode Color Scheme - https://www.realtimecolors.com/?colors=e8ebf5-0b0f1d-99aade-26408d-3059d2&fonts=Ubuntu-Ubuntu

index.css

@media (prefers-color-scheme: light) {
  :root {
    /* https://www.realtimecolors.com/?colors=070c03-f7fbf4-9aca3f-9ae4e2-5e97d4&fonts=Ubuntu-Ubuntu */
    --text-color: #070c03;
    --background-color: #f7fbf4;
    --primary-color: #9aca3f;
    --secondary-color: #9ae4e2;
    --accent-color: #5e97d4;
    --error-color: #a80b0b;
    --success-color: #0e5d3c;
    --link-color: #293a6f;
    background-color: var(--background-color);
    color: var(--text-color);
  }
}

@media (prefers-color-scheme: dark) {
  :root {
    /* https://www.realtimecolors.com/?colors=e8ebf5-0b0f1d-99aade-26408d-3059d2&fonts=Ubuntu-Ubuntu */
    --text-color: #e8ebf5;
    --background-color: #0b0f1d;
    --primary-color: #99aade;
    --secondary-color: #26408d;
    --accent-color: #3059d2;
    --error-color: #dc2626;
    --success-color: #22c55e;
    --link-color: #e6f0f7;
    background-color: var(--background-color);
    color: var(--text-color);
  }
}