refactor(admin): use inline pixel heights for overview charts

Refactors the admin overview dashboard charts to use inline pixel heights (up to 150px) instead of CSS variables and percentage-based heights. This provides more robust rendering and layout control.

Changes include:
- Replacing `Height` with `HeightPx` in chart bar structures.
- Rendering inline styles for height and width on charts and status bars.
- Adding fallback data attributes (`data-height-px`, `data-chart-value`, etc.) and loading a new fallback script (`25-admin-charts.js`).
- Updating and expanding test coverage to assert correct scaling and HTML rendering.

backend/libs/handlers/accounts_test.go

@@ -707,24 +707,60 @@ func TestAdminOverviewChartsUseZeroAndFullHeights(t *testing.T) {
 	for i, bar := range overview.UploadDays {
 		want := 0
 		if i == len(overview.UploadDays)-1 {
-			want = 100
+			want = 150
 		}
-		if bar.Height != want {
-			t.Fatalf("upload bar %d height = %d, want %d", i, bar.Height, want)
+		if bar.HeightPx != want {
+			t.Fatalf("upload bar %d height = %d, want %d", i, bar.HeightPx, want)
 		}
 	}
 	for i, bar := range overview.StorageDays {
 		want := 0
 		if i == len(overview.StorageDays)-1 {
-			want = 100
+			want = 150
 		}
-		if bar.Height != want {
-			t.Fatalf("storage bar %d height = %d, want %d", i, bar.Height, want)
+		if bar.HeightPx != want {
+			t.Fatalf("storage bar %d height = %d, want %d", i, bar.HeightPx, want)
 		}
 	}
+	if overview.StatusBars[0].WidthPercent != 100 {
+		t.Fatalf("active status width = %d, want 100", overview.StatusBars[0].WidthPercent)
+	}
 }
 
-func TestAdminOverviewRendersBarHeightVariables(t *testing.T) {
+func TestAdminOverviewChartsScaleRelativeToVisibleRange(t *testing.T) {
+	now := time.Now().UTC()
+	today := time.Date(now.Year(), now.Month(), now.Day(), 12, 0, 0, 0, time.UTC)
+	yesterday := today.AddDate(0, 0, -1)
+	twoDaysAgo := today.AddDate(0, 0, -2)
+	boxes := []services.AdminBox{
+		{ID: "today-1", CreatedAt: today, TotalSize: 30},
+		{ID: "today-2", CreatedAt: today, TotalSize: 30},
+		{ID: "today-3", CreatedAt: today, TotalSize: 30},
+		{ID: "yesterday-1", CreatedAt: yesterday, TotalSize: 20},
+		{ID: "yesterday-2", CreatedAt: yesterday, TotalSize: 20},
+		{ID: "two-days-ago", CreatedAt: twoDaysAgo, TotalSize: 10},
+	}
+	overview := buildAdminOverview(boxes, services.AdminStats{TotalBoxes: 6, ExpiredBoxes: 2, ProtectedBoxes: 1})
+
+	last := len(overview.UploadDays) - 1
+	if overview.UploadDays[last].HeightPx != 150 {
+		t.Fatalf("3-upload day height = %d, want 150", overview.UploadDays[last].HeightPx)
+	}
+	if overview.UploadDays[last-1].HeightPx != 100 {
+		t.Fatalf("2-upload day height = %d, want 100", overview.UploadDays[last-1].HeightPx)
+	}
+	if overview.UploadDays[last-2].HeightPx != 50 {
+		t.Fatalf("1-upload day height = %d, want 50", overview.UploadDays[last-2].HeightPx)
+	}
+	if overview.StorageDays[last].HeightPx != 150 || overview.StorageDays[last-1].HeightPx != 66 || overview.StorageDays[last-2].HeightPx != 16 {
+		t.Fatalf("storage heights = %d/%d/%d, want 150/66/16", overview.StorageDays[last].HeightPx, overview.StorageDays[last-1].HeightPx, overview.StorageDays[last-2].HeightPx)
+	}
+	if overview.StatusBars[0].WidthPercent != 100 || overview.StatusBars[1].WidthPercent != 50 || overview.StatusBars[2].WidthPercent != 25 {
+		t.Fatalf("status widths = %d/%d/%d, want 100/50/25", overview.StatusBars[0].WidthPercent, overview.StatusBars[1].WidthPercent, overview.StatusBars[2].WidthPercent)
+	}
+}
+
+func TestAdminOverviewRendersInlineBarDimensions(t *testing.T) {
 	app, cleanup := newTestApp(t)
 	defer cleanup()
 	adminToken := createAdminSession(t, app)
@@ -738,11 +774,26 @@ func TestAdminOverviewRendersBarHeightVariables(t *testing.T) {
 		t.Fatalf("AdminDashboard status = %d, body = %s", response.Code, response.Body.String())
 	}
 	body := response.Body.String()
-	if !strings.Contains(body, "--bar-height: 100%") {
-		t.Fatalf("admin overview did not render a full-height bar: %s", body)
+	if !strings.Contains(body, `style="height: 150px"`) {
+		t.Fatalf("admin overview did not render a full-height pixel bar: %s", body)
 	}
-	if strings.Contains(body, `style="height:`) {
-		t.Fatalf("admin overview still uses fragile percent height styles: %s", body)
+	if !strings.Contains(body, `data-height-px="150"`) || !strings.Contains(body, `data-chart-value=`) {
+		t.Fatalf("admin overview did not render chart fallback data attributes: %s", body)
+	}
+	if !strings.Contains(body, `style="height: 0px"`) {
+		t.Fatalf("admin overview did not render zero pixel bars: %s", body)
+	}
+	if !strings.Contains(body, `style="width: 100%"`) {
+		t.Fatalf("admin overview did not render a full-width status bar: %s", body)
+	}
+	if !strings.Contains(body, `data-width-percent="100"`) || !strings.Contains(body, `data-stat-value=`) {
+		t.Fatalf("admin overview did not render status fallback data attributes: %s", body)
+	}
+	if strings.Contains(body, "--bar-height") {
+		t.Fatalf("admin overview still uses css variable bar heights: %s", body)
+	}
+	if !strings.Contains(body, "/static/js/25-admin-charts.js?version=test") {
+		t.Fatalf("admin overview did not load chart fallback script: %s", body)
 	}
 }
 

backend/libs/handlers/admin.go

@@ -161,13 +161,15 @@ type adminOverview struct {
 type adminChartBar struct {
 	Label    string
 	Value    string
-	Height int // 0-100, percent of the tallest bar
+	HeightPx int
+	RawValue int64
 }
 
 type adminStatBar struct {
 	Label        string
 	Value        string
-	Percent int
+	RawValue     int
+	WidthPercent int
 }
 
 type adminBoxView struct {
@@ -336,6 +338,7 @@ func (a *App) recentBoxViews(boxes []services.AdminBox, limit int) []adminBoxVie
 // status distributions for the overview dashboard.
 func buildAdminOverview(boxes []services.AdminBox, stats services.AdminStats) adminOverview {
 	const days = 14
+	const chartMaxHeightPx = 150
 	now := time.Now().UTC()
 	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, time.UTC)
 
@@ -376,12 +379,14 @@ func buildAdminOverview(boxes []services.AdminBox, stats services.AdminStats) ad
 		uploadDays[i] = adminChartBar{
 			Label:    labels[i],
 			Value:    strconv.Itoa(counts[i]),
-			Height: scaleHeight(int64(counts[i]), int64(maxCount)),
+			HeightPx: scaleHeightPx(int64(counts[i]), int64(maxCount), chartMaxHeightPx),
+			RawValue: int64(counts[i]),
 		}
 		storageDays[i] = adminChartBar{
 			Label:    labels[i],
 			Value:    helpers.FormatBytes(bytes[i]),
-			Height: scaleHeight(bytes[i], maxBytes),
+			HeightPx: scaleHeightPx(bytes[i], maxBytes, chartMaxHeightPx),
+			RawValue: bytes[i],
 		}
 	}
 
@@ -389,10 +394,11 @@ func buildAdminOverview(boxes []services.AdminBox, stats services.AdminStats) ad
 	if activeBoxes < 0 {
 		activeBoxes = 0
 	}
+	maxStatusValue := maxInt(activeBoxes, stats.ExpiredBoxes, stats.ProtectedBoxes)
 	statusBars := []adminStatBar{
-		{Label: "Active", Value: strconv.Itoa(activeBoxes), Percent: percentOf(activeBoxes, stats.TotalBoxes)},
-		{Label: "Expired", Value: strconv.Itoa(stats.ExpiredBoxes), Percent: percentOf(stats.ExpiredBoxes, stats.TotalBoxes)},
-		{Label: "Password-protected", Value: strconv.Itoa(stats.ProtectedBoxes), Percent: percentOf(stats.ProtectedBoxes, stats.TotalBoxes)},
+		{Label: "Active", Value: strconv.Itoa(activeBoxes), RawValue: activeBoxes, WidthPercent: percentOf(activeBoxes, maxStatusValue)},
+		{Label: "Expired", Value: strconv.Itoa(stats.ExpiredBoxes), RawValue: stats.ExpiredBoxes, WidthPercent: percentOf(stats.ExpiredBoxes, maxStatusValue)},
+		{Label: "Password-protected", Value: strconv.Itoa(stats.ProtectedBoxes), RawValue: stats.ProtectedBoxes, WidthPercent: percentOf(stats.ProtectedBoxes, maxStatusValue)},
 	}
 
 	return adminOverview{
@@ -402,13 +408,16 @@ func buildAdminOverview(boxes []services.AdminBox, stats services.AdminStats) ad
 	}
 }
 
-func scaleHeight(value, max int64) int {
+func scaleHeightPx(value, max int64, maxHeightPx int) int {
 	if max <= 0 || value <= 0 {
 		return 0
 	}
-	height := int(value * 100 / max)
-	if height < 4 {
-		height = 4
+	height := int(value * int64(maxHeightPx) / max)
+	if height < 8 {
+		height = 8
+	}
+	if height > maxHeightPx {
+		return maxHeightPx
 	}
 	return height
 }
@@ -420,6 +429,16 @@ func percentOf(value, total int) int {
 	return value * 100 / total
 }
 
+func maxInt(values ...int) int {
+	max := 0
+	for _, value := range values {
+		if value > max {
+			max = value
+		}
+	}
+	return max
+}
+
 func (a *App) AdminUsers(w http.ResponseWriter, r *http.Request) {
 	if !a.requireAdmin(w, r) {
 		return

backend/static/css/50-admin.css

@@ -198,9 +198,9 @@
 .bar-chart {
   display: grid;
   grid-template-columns: repeat(14, minmax(0, 1fr));
-  align-items: stretch;
+  align-items: end;
   gap: 0.4rem;
-  min-height: 15rem;
+  min-height: 13rem;
   margin-top: 1.25rem;
   padding-top: 0.5rem;
 }
@@ -214,11 +214,13 @@
 }
 
 .bar-chart-track {
-  position: relative;
+  display: flex;
+  align-items: flex-end;
+  justify-content: center;
   flex: 1 1 auto;
   width: 100%;
   max-width: 1.8rem;
-  min-height: 9rem;
+  height: 150px;
   margin: 0 auto;
   border-bottom: 2px solid color-mix(in srgb, var(--primary, #8b5cf6) 75%, transparent);
   border-radius: 0.45rem 0.45rem 0 0;
@@ -228,12 +230,8 @@
 
 .bar-chart-bar {
   display: block;
-  position: absolute;
-  left: 0;
-  right: 0;
-  bottom: 0;
   width: 100%;
-  height: var(--bar-height, 0%);
+  min-height: 0;
   border-radius: 6px 6px 0 0;
   background: linear-gradient(180deg, var(--primary-hover, #7c3aed), var(--primary, #8b5cf6));
   box-shadow: 0 0 18px color-mix(in srgb, var(--primary, #8b5cf6) 35%, transparent);
@@ -278,6 +276,8 @@
 }
 
 .stat-bar-track {
+  display: block;
+  width: 100%;
   margin-top: 0.35rem;
   height: 0.55rem;
   border-radius: 999px;
@@ -288,6 +288,7 @@
 .stat-bar-fill {
   display: block;
   height: 100%;
+  min-width: 0;
   border-radius: 999px;
   background: var(--primary, #8b5cf6);
 }

backend/static/js/25-admin-charts.js

@@ -0,0 +1,57 @@
+(function () {
+  const maxBarHeight = 150;
+
+  function numberAttr(element, name) {
+    const value = Number(element.getAttribute(name));
+    return Number.isFinite(value) ? value : 0;
+  }
+
+  function applyChartBars() {
+    document.querySelectorAll(".bar-chart").forEach((chart) => {
+      const bars = Array.from(chart.querySelectorAll(".bar-chart-col"));
+      const maxValue = Math.max(0, ...bars.map((bar) => numberAttr(bar, "data-chart-value")));
+
+      bars.forEach((bar) => {
+        const fill = bar.querySelector(".bar-chart-bar");
+        if (!fill) {
+          return;
+        }
+        const value = numberAttr(bar, "data-chart-value");
+        let height = numberAttr(fill, "data-height-px");
+        if (maxValue > 0) {
+          height = value <= 0 ? 0 : Math.max(8, Math.round((value / maxValue) * maxBarHeight));
+        }
+        fill.style.height = `${Math.min(maxBarHeight, height)}px`;
+      });
+    });
+  }
+
+  function applyStatusBars() {
+    const rows = Array.from(document.querySelectorAll(".stat-bar"));
+    const maxValue = Math.max(0, ...rows.map((row) => numberAttr(row, "data-stat-value")));
+
+    rows.forEach((row) => {
+      const fill = row.querySelector(".stat-bar-fill");
+      if (!fill) {
+        return;
+      }
+      const value = numberAttr(row, "data-stat-value");
+      let width = numberAttr(fill, "data-width-percent");
+      if (maxValue > 0) {
+        width = value <= 0 ? 0 : Math.round((value / maxValue) * 100);
+      }
+      fill.style.width = `${Math.max(0, Math.min(100, width))}%`;
+    });
+  }
+
+  function init() {
+    applyChartBars();
+    applyStatusBars();
+  }
+
+  if (document.readyState === "loading") {
+    document.addEventListener("DOMContentLoaded", init);
+  } else {
+    init();
+  }
+})();

backend/templates/layouts/base.html

@@ -32,6 +32,7 @@
   <script defer src="/static/js/00-utils.js?version={{.AppVersion}}"></script>
   <script defer src="/static/js/10-file-browser.js?version={{.AppVersion}}"></script>
   <script defer src="/static/js/20-storage-admin.js?version={{.AppVersion}}"></script>
+  <script defer src="/static/js/25-admin-charts.js?version={{.AppVersion}}"></script>
   <script defer src="/static/js/30-token-copy.js?version={{.AppVersion}}"></script>
   <script defer src="/static/js/35-pagination.js?version={{.AppVersion}}"></script>
   <script defer src="/static/js/40-upload.js?version={{.AppVersion}}"></script>

backend/templates/pages/admin.html

@@ -65,9 +65,9 @@
         <p class="muted-copy">New boxes created over the last 14 days.</p>
         <div class="bar-chart" role="img" aria-label="Uploads per day for the last 14 days">
           {{range .Data.Overview.UploadDays}}
-          <div class="bar-chart-col" title="{{.Label}}: {{.Value}}">
+          <div class="bar-chart-col" title="{{.Label}}: {{.Value}}" data-chart-value="{{.RawValue}}">
             <span class="bar-chart-value">{{.Value}}</span>
-            <span class="bar-chart-track"><span class="bar-chart-bar" style="--bar-height: {{.Height}}%"></span></span>
+            <span class="bar-chart-track"><span class="bar-chart-bar" data-height-px="{{.HeightPx}}" style="height: {{.HeightPx}}px"></span></span>
             <span class="bar-chart-label">{{.Label}}</span>
           </div>
           {{end}}
@@ -81,9 +81,9 @@
         <p class="muted-copy">Share of all {{.Data.Stats.TotalBoxes}} boxes.</p>
         <div class="stat-bars">
           {{range .Data.Overview.StatusBars}}
-          <div class="stat-bar">
+          <div class="stat-bar" data-stat-value="{{.RawValue}}">
             <span>{{.Label}} <strong>{{.Value}}</strong></span>
-            <span class="stat-bar-track"><span class="stat-bar-fill" style="width: {{.Percent}}%"></span></span>
+            <span class="stat-bar-track"><span class="stat-bar-fill" data-width-percent="{{.WidthPercent}}" style="width: {{.WidthPercent}}%"></span></span>
           </div>
           {{end}}
         </div>
@@ -97,9 +97,9 @@
       <p class="muted-copy">Bytes uploaded over the last 14 days.</p>
       <div class="bar-chart" role="img" aria-label="Storage added per day for the last 14 days">
         {{range .Data.Overview.StorageDays}}
-        <div class="bar-chart-col" title="{{.Label}}: {{.Value}}">
+        <div class="bar-chart-col" title="{{.Label}}: {{.Value}}" data-chart-value="{{.RawValue}}">
           <span class="bar-chart-value">{{.Value}}</span>
-          <span class="bar-chart-track"><span class="bar-chart-bar" style="--bar-height: {{.Height}}%"></span></span>
+          <span class="bar-chart-track"><span class="bar-chart-bar" data-height-px="{{.HeightPx}}" style="height: {{.HeightPx}}px"></span></span>
           <span class="bar-chart-label">{{.Label}}</span>
         </div>
         {{end}}