fix: progress bar not rendering — replace float:left with position:absolute

float:left on .progress-segment was ignored inside the overflow:hidden
position:relative .progress-bar container, so the coloured fill never
appeared. Absolute positioning from top:0 left:0 with the JS-assigned
width renders correctly.

public/style.css

@@ -519,13 +519,15 @@ body {
 }
 
 .progress-segment {
+  position: absolute;
+  top: 0;
+  left: 0;
   height: 100%;
   transition: width 0.3s ease;
 }
 
 .progress-segment.downloaded {
   background: linear-gradient(90deg, var(--progress-fill-start) 0%, var(--progress-fill-end) 100%);
-  float: left;
 }
 
 .progress-text {