place tooltip above line of line chart, otherwise fall back to 50% bottom position (default)

Author: filmaj

src/components/_tooltips.scss

@@ -7,8 +7,13 @@
     // Position
     position: absolute;
     z-index: 1;
-    inset-block-end: 50%;
+    // if --start / --end exist, then it's a line chart, and we calculate
+    // the larger of the two to place the tooltip above the line segment;
+    // if --start and --end don't exist, fallback to 0.5 * 100% = 50%,
+    // which is the default tooltip position for e.g. bar charts
+    inset-block-end: calc(max(var(--start, 0.5), var(--end, 0.5)) * 100%);
     inset-inline-start: 50%;
+    transform: translateX(-50%); // translateX for both bar & column chart
     width: max-content;
     padding: 5px 10px;
     border-radius: 6px;