diff --git a/assets/sai.css b/assets/sai.css
index 321814e..f54c72c 100644
--- a/assets/sai.css
+++ b/assets/sai.css
@@ -2467,7 +2467,8 @@ table.tt {
 table.tt th.tt-th {
 	position: sticky;
 	top: 0;
-	z-index: 1;
+	/* above the platform icons: img.zup is positioned at z-index 11 */
+	z-index: 20;
 	background: #f1f5f9;
 	color: #1e293b;
 	text-align: left;
diff --git a/assets/sai.js b/assets/sai.js
index ed246e1..27f63b0 100644
--- a/assets/sai.js
+++ b/assets/sai.js
@@ -1160,9 +1160,8 @@ function sai_taskinfo_render(t, now_ut)
 		/* started is a unix time, in seconds */
 		s += "<span class=\"ti5\"> " +
 		     agify(now_ut, t.t.started) + " ago, Dur: " +
-		     (t.t.duration ? t.t.duration / 1000000 :
-			now_ut - t.t.started).toFixed(1) +
-			"s</span><div id=\"sai_arts\"></div><div id=\"metrics-summary-" + san(t.t.uuid) + "\"></div>";
+		     sai_tt_fmt_dur(sai_tt_dur_secs(t.t, now_ut)) +
+			"</span><div id=\"sai_arts\"></div><div id=\"metrics-summary-" + san(t.t.uuid) + "\"></div>";
 		sai_arts = "";
 	}
 
@@ -2019,13 +2018,21 @@ function sai_tt_is_ongoing(state)
 	return state === 1 || state === 2 || state === 6 || state === 10;
 }
 
-/* wallclock seconds the task took / has taken so far, or -1 if never started */
+/*
+ * Wallclock seconds the task has been building, or -1 if it never started.
+ *
+ * While it's still going, that's now minus the time the first step was
+ * accepted (t.started, unix secs).  Once it reached a disposition, the
+ * server stored the elapsed seconds at that moment in t.duration (see
+ * sais_process_rej()); it also refreshes t.duration at each step boundary,
+ * so it must not be preferred over the live clock for an ongoing task.
+ */
 function sai_tt_dur_secs(t, now_ut)
 {
-	if (t.duration)
-		return t.duration / 1000000;
 	if (t.started && sai_tt_is_ongoing(t.state))
 		return Math.max(0, now_ut - t.started);
+	if (t.duration)
+		return t.duration;
 
 	return -1;
 }
@@ -2185,10 +2192,10 @@ function sai_tt_row_key(tr, key, now_ut)
 	case "started":
 		return parseInt(d.started) > 0 ? parseInt(d.started) : null;
 	case "duration":
-		if (parseInt(d.dur) > 0)
-			return parseInt(d.dur) / 1000000;
 		if (parseInt(d.started) > 0 && sai_tt_is_ongoing(state))
 			return now_ut - parseInt(d.started);
+		if (parseInt(d.dur) > 0)
+			return parseInt(d.dur);
 		return null;
 	case "step":
 		return sai_tt_state_rank(state) * 10000 + (parseInt(d.step) + 1);
@@ -2300,7 +2307,7 @@ function sai_tt_tick()
 	rows.forEach(function(tr) {
 		var d = tr.dataset;
 
-		if (parseInt(d.dur) > 0 || !(parseInt(d.started) > 0) ||
+		if (!(parseInt(d.started) > 0) ||
 		    !sai_tt_is_ongoing(parseInt(d.state)))
 			return;