fix: fix dark mode timeline colors (#705)

* fix: show timeline event colors in dark mode

dark mode overrides every border-color with an `!important` rule (evil).
This fix cancels this override on every element that has a `border*` inline style (ie. the events divs in the timeline). 

fixes #611

* fix: better css rule for dark mode border colors

previous rule would break dark mode's border color override when using inline non-color-related border styles (ie. `border-radius` or `border-width`).

This fix makes the color override be disabled only when using inline `border-color` or `border` styles.

Author: t-fritsch

static/dark.css

@@ -170,7 +170,7 @@ hr {
   background-color: #282c32 !important;
 }
 
-#visualization *, svg,
+#visualization *:not([style*="border:"]):not([style*="border-color:"]), svg,
 .nav.nav-tabs,
 .btn-outline-secondary {
   border-color: #282c32 !important;
@@ -264,4 +264,4 @@ div[style="color: rgb(85, 85, 85); font-size: 0.9em;"] {
   color: hsl(355, 70%, 90%);
   background-color: hsl(355, 60%, 30%);
   border-color: hsl(355, 60%, 25%);
-}
+}