Change CSS framework from PicoCSS to Bootstrap 5.3

assets/bs/cosmo/_bootswatch.scss

@@ -0,0 +1,53 @@
+// Cosmo 5.3.8
+// Bootswatch
+
+
+// Variables
+
+$web-font-path: "https://fonts.googleapis.com/css2?family=Source+Sans+Pro:wght@300;400;700&display=swap" !default;
+@if $web-font-path {
+  @import url("#{$web-font-path}");
+}
+
+// Typography
+
+body {
+  -webkit-font-smoothing: antialiased;
+}
+
+// Tables
+
+.table-primary,
+.table-secondary,
+.table-success,
+.table-warning,
+.table-danger,
+.table-info,
+.table-light {
+  --#{$prefix}table-color: #{$body-color};
+}
+
+// Forms
+
+.form-range::-moz-range-thumb {
+  border-radius: inherit;
+}
+
+// Indicators
+
+.badge {
+  &.bg-light {
+    color: $dark;
+  }
+}
+
+// Progress bars
+
+.progress {
+  @include box-shadow(none);
+
+  .progress-bar {
+    font-size: 8px;
+    line-height: 8px;
+  }
+}

assets/bs/cosmo/_variables.scss

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+// Cosmo 5.3.8
+// Bootswatch
+
+$theme: "cosmo" !default;
+
+//
+// Color system
+//
+
+$white:    #fff !default;
+$gray-100: #f8f9fa !default;
+$gray-200: #e9ecef !default;
+$gray-300: #dee2e6 !default;
+$gray-400: #ced4da !default;
+$gray-500: #adb5bd !default;
+$gray-600: #868e96 !default;
+$gray-700: #495057 !default;
+$gray-800: #373a3c !default;
+$gray-900: #212529 !default;
+$black:    #000 !default;
+
+$blue:    #2780e3 !default;
+$indigo:  #6610f2 !default;
+$purple:  #613d7c !default;
+$pink:    #e83e8c !default;
+$red:     #ff0039 !default;
+$orange:  #f0ad4e !default;
+$yellow:  #ff7518 !default;
+$green:   #3fb618 !default;
+$teal:    #20c997 !default;
+$cyan:    #9954bb !default;
+
+$primary:       $blue !default;
+$secondary:     $gray-800 !default;
+$success:       $green !default;
+$info:          $cyan !default;
+$warning:       $yellow !default;
+$danger:        $red !default;
+$light:         $gray-100 !default;
+$dark:          $gray-800 !default;
+
+$min-contrast-ratio:   2.6 !default;
+
+// Options
+
+$enable-rounded: false !default;
+
+// Body
+
+$body-color:    $gray-800 !default;
+
+// Fonts
+
+// stylelint-disable-next-line value-keyword-case
+$font-family-sans-serif:    "Source Sans Pro", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol" !default;
+$headings-font-weight:      400 !default;
+
+// Tables
+
+$table-color:               initial !default;
+
+// Navbar
+
+$navbar-dark-hover-color:       rgba($white, 1) !default;
+$navbar-light-hover-color:      rgba($black, .9) !default;
+
+// Alerts
+
+$alert-border-width:            0 !default;
+
+// Progress bars
+
+$progress-height:               .5rem !default;