diff --git a/src/components/SprintGanttView.tsx b/src/components/SprintGanttView.tsx
index bca3949..a785da3 100644
--- a/src/components/SprintGanttView.tsx
+++ b/src/components/SprintGanttView.tsx
@@ -9,13 +9,17 @@ import {
   epicScopeSprintProgress,
   formatGanttSprintSubtitleLines,
   formatSprintRangeFr,
+  ganttDayColumns,
+  ganttMonthBands,
   ganttRangeFromSprintsAndMilestones,
+  ganttSubheaderTicks,
+  ganttVerticalGuideXs,
   milestoneTooltipText,
   msToX,
   parseIsoMs,
   pixelsPerDay,
-  timelineTicks,
   timelineWidthPx,
+  type GanttDayColumn,
   type GanttTimeScale,
   sprintBarBounds,
   sprintBarFillPercent,
@@ -84,6 +88,57 @@ const SCALE_LABELS: Record<GanttTimeScale, string> = {
   month: 'Mois',
 }
 
+function GanttTimelineBackdrop({
+  dayColumns,
+  guideXs,
+  todayX,
+  todayClamped,
+  compact,
+}: {
+  dayColumns: GanttDayColumn[]
+  guideXs: number[]
+  todayX: number
+  todayClamped: 'before' | 'inside' | 'after'
+  compact?: boolean
+}) {
+  const insetY = compact ? 'bottom-1 top-1' : 'inset-y-0'
+  return (
+    <>
+      {dayColumns
+        .filter((c) => c.isWeekend)
+        .map((c) => (
+          <div
+            key={c.dayStartMs}
+            className={`pointer-events-none absolute z-0 bg-slate-800/[0.38] ${insetY}`}
+            style={{ left: `${c.x0}px`, width: `${Math.max(0, c.x1 - c.x0)}px` }}
+            aria-hidden
+          />
+        ))}
+      {guideXs.map((gx, i) => (
+        <div
+          key={`vg-${i}-${Math.round(gx * 10)}`}
+          className={`pointer-events-none absolute z-[1] w-px bg-slate-600/50 ${insetY}`}
+          style={{ left: `${gx}px` }}
+          aria-hidden
+        />
+      ))}
+      <div
+        className={`pointer-events-none absolute z-[2] w-0 border-l-2 border-dashed border-emerald-400/95 shadow-[0_0_10px_rgba(52,211,153,0.35)] ${insetY} ${
+          todayClamped !== 'inside' ? 'opacity-45' : ''
+        }`}
+        style={{ left: `${todayX}px` }}
+        title={
+          todayClamped === 'inside'
+            ? 'Aujourd’hui'
+            : todayClamped === 'before'
+              ? 'Aujourd’hui (avant la période affichée)'
+              : 'Aujourd’hui (après la période affichée)'
+        }
+      />
+    </>
+  )
+}
+
 export function SprintGanttView({
   sprints,
   milestones,
@@ -132,10 +187,21 @@ export function SprintGanttView({
     [startMs, endMs, ppd],
   )
 
-  const maxTicks = useMemo(() => Math.floor(widthPx / 72), [widthPx])
-  const ticks = useMemo(
-    () => timelineTicks(timeScale, startMs, endMs, maxTicks),
-    [timeScale, startMs, endMs, maxTicks],
+  const dayColumns = useMemo(
+    () => ganttDayColumns(startMs, endMs, widthPx),
+    [startMs, endMs, widthPx],
+  )
+  const monthBands = useMemo(
+    () => ganttMonthBands(startMs, endMs, widthPx),
+    [startMs, endMs, widthPx],
+  )
+  const subheaderTicks = useMemo(
+    () => ganttSubheaderTicks(timeScale, startMs, endMs, widthPx),
+    [timeScale, startMs, endMs, widthPx],
+  )
+  const guideXs = useMemo(
+    () => ganttVerticalGuideXs(timeScale, startMs, endMs, widthPx),
+    [timeScale, startMs, endMs, widthPx],
   )
 
   const todayLine = useMemo(() => {
@@ -204,8 +270,9 @@ export function SprintGanttView({
           </h2>
           <p className="mt-1 max-w-3xl text-xs leading-relaxed text-slate-500">
             Échelle <span className="text-slate-400">jour / semaine / mois</span> et zoom (loupe) : la
-            timeline s’étire en pixels par jour — faites défiler horizontalement. Barre = charge
-            (champ Sprint) ou avancement calendaire. Losanges = jalons (survol pour le détail).
+            timeline s’étire en pixels par jour — faites défiler horizontalement. En-tête : mois puis
+            jours / repères ; week-ends en fond plus sombre. Barre = charge (champ Sprint) ou
+            avancement calendaire. Losanges = jalons (survol pour le détail).
           </p>
         </div>
         <button
@@ -310,49 +377,50 @@ export function SprintGanttView({
             width: `${220 + widthPx}px`,
           }}
         >
-          <div className="sticky left-0 z-30 border-b border-r border-white/[0.08] bg-slate-950/95 px-2 py-2 text-[10px] font-semibold uppercase tracking-wide text-slate-500 backdrop-blur-sm">
+          <div className="sticky left-0 z-40 flex min-h-[4.25rem] flex-col justify-center border-b border-r border-white/[0.08] bg-slate-950/95 px-2 py-2 text-[10px] font-semibold uppercase tracking-wide text-slate-500 backdrop-blur-sm">
             Piste
           </div>
-          <div className="relative h-9 border-b border-white/[0.08] bg-slate-900/40">
-            {ticks.map((t) => {
-              const x = msToX(t.ms, startMs, endMs, widthPx)
-              return (
+          <div
+            className="relative min-h-[4.25rem] border-b border-white/[0.08] bg-slate-900/55"
+            style={{ width: `${widthPx}px` }}
+          >
+            <div className="relative h-8 border-b border-white/15">
+              {monthBands.map((b) => (
+                <div
+                  key={b.monthStartMs}
+                  className="absolute inset-y-0 flex items-center justify-center border-r border-white/20 bg-slate-900/80 text-[11px] font-semibold capitalize tracking-tight text-slate-200"
+                  style={{ left: `${b.x0}px`, width: `${Math.max(0, b.x1 - b.x0)}px` }}
+                >
+                  <span className="truncate px-1.5 text-center" title={b.label}>
+                    {b.label}
+                  </span>
+                </div>
+              ))}
+            </div>
+            <div className="relative h-7">
+              {subheaderTicks.map((t, idx) => (
                 <span
-                  key={t.ms}
-                  className="absolute top-1 -translate-x-1/2 whitespace-nowrap text-[10px] text-slate-400"
-                  style={{ left: `${x}px` }}
+                  key={`${timeScale}-${t.ms}-${idx}`}
+                  className={`absolute top-1 -translate-x-1/2 select-none whitespace-nowrap text-[10px] ${
+                    t.major ? 'font-semibold text-slate-300' : 'text-slate-500'
+                  }`}
+                  style={{ left: `${t.x}px` }}
                 >
                   {t.label}
                 </span>
-              )
-            })}
+              ))}
+            </div>
           </div>
 
           <div className="sticky left-0 z-30 flex items-center border-b border-r border-white/[0.06] bg-slate-950/95 px-2 py-2 text-[10px] font-semibold uppercase tracking-wide text-violet-300/90 backdrop-blur-sm">
             Jalons
           </div>
           <div className="relative h-12 border-b border-white/[0.06] bg-slate-900/50">
-            {ticks.map((t) => (
-              <div
-                key={`jg-${t.ms}`}
-                className={`pointer-events-none absolute bottom-0 top-0 w-px ${
-                  t.major ? 'bg-slate-500/50' : 'border-l border-dashed border-slate-600/40'
-                }`}
-                style={{ left: `${msToX(t.ms, startMs, endMs, widthPx)}px` }}
-              />
-            ))}
-            <div
-              className={`pointer-events-none absolute bottom-0 top-0 z-10 w-px bg-emerald-400 shadow-[0_0_10px_rgba(52,211,153,0.65)] ${
-                todayLine.clamped !== 'inside' ? 'opacity-45' : ''
-              }`}
-              style={{ left: `${todayLine.x}px` }}
-              title={
-                todayLine.clamped === 'inside'
-                  ? 'Aujourd’hui'
-                  : todayLine.clamped === 'before'
-                    ? 'Aujourd’hui (avant la période affichée)'
-                    : 'Aujourd’hui (après la période affichée)'
-              }
+            <GanttTimelineBackdrop
+              dayColumns={dayColumns}
+              guideXs={guideXs}
+              todayX={todayLine.x}
+              todayClamped={todayLine.clamped}
             />
             {sortedMilestones.map((m) => {
               const ms = parseIsoMs(`${m.date}T12:00:00`)
@@ -406,18 +474,12 @@ export function SprintGanttView({
                 </div>
                 <div className="relative min-h-[48px] border-b border-white/[0.06] bg-slate-900/30 py-2">
                   <div className="relative mx-0 h-10">
-                    {ticks.map((t) => (
-                      <div
-                        key={`sg-${s.id}-${t.ms}`}
-                        className="pointer-events-none absolute bottom-1 top-1 w-px bg-slate-700/35"
-                        style={{ left: `${msToX(t.ms, startMs, endMs, widthPx)}px` }}
-                      />
-                    ))}
-                    <div
-                      className={`pointer-events-none absolute bottom-1 top-1 z-10 w-px bg-emerald-400/85 ${
-                        todayLine.clamped !== 'inside' ? 'opacity-40' : ''
-                      }`}
-                      style={{ left: `${todayLine.x}px` }}
+                    <GanttTimelineBackdrop
+                      dayColumns={dayColumns}
+                      guideXs={guideXs}
+                      todayX={todayLine.x}
+                      todayClamped={todayLine.clamped}
+                      compact
                     />
                     <div
                       className="absolute bottom-1 top-1 overflow-hidden rounded-full bg-gradient-to-r from-slate-700/90 to-sky-950/50 ring-1 ring-sky-500/25"
diff --git a/src/lib/sprintGantt.ts b/src/lib/sprintGantt.ts
index 1ae833f..55433c2 100644
--- a/src/lib/sprintGantt.ts
+++ b/src/lib/sprintGantt.ts
@@ -109,7 +109,8 @@ export function timelineTicks(
   return ticks
 }
 
-function startOfWeekMondayLocal(ms: number): number {
+/** Premier instant (midi local) du lundi de la semaine calendaire contenant `ms`. */
+export function startOfWeekMondayLocal(ms: number): number {
   const d = new Date(ms)
   d.setHours(12, 0, 0, 0)
   const day = d.getDay()
@@ -199,6 +200,194 @@ export function monthTicksBetween(startMs: number, endMs: number): { ms: number;
   return ticks
 }
 
+/** Colonne calendaire (jour) projetée sur la timeline — week-ends, grille jour. */
+export type GanttDayColumn = {
+  dayStartMs: number
+  weekday: number
+  x0: number
+  x1: number
+  isWeekend: boolean
+}
+
+/**
+ * Une entrée par jour local qui intersecte [startMs, endMs] (bornes en pixels pour le fond).
+ */
+export function ganttDayColumns(startMs: number, endMs: number, widthPx: number): GanttDayColumn[] {
+  const cols: GanttDayColumn[] = []
+  const iter = new Date(startMs)
+  iter.setHours(0, 0, 0, 0)
+  if (iter.getTime() > startMs) iter.setDate(iter.getDate() - 1)
+
+  let guard = 0
+  while (iter.getTime() < endMs + MS_DAY && guard++ < 800) {
+    const dayStart = iter.getTime()
+    const wd = iter.getDay()
+    const next = new Date(iter)
+    next.setDate(next.getDate() + 1)
+    const dayEnd = next.getTime()
+    if (dayEnd > startMs && dayStart < endMs) {
+      const x0 = msToX(Math.max(dayStart, startMs), startMs, endMs, widthPx)
+      const x1 = msToX(Math.min(dayEnd, endMs), startMs, endMs, widthPx)
+      if (x1 > x0 + 0.02) {
+        cols.push({
+          dayStartMs: dayStart,
+          weekday: wd,
+          x0,
+          x1,
+          isWeekend: wd === 0 || wd === 6,
+        })
+      }
+    }
+    iter.setDate(iter.getDate() + 1)
+  }
+  return cols
+}
+
+/** Bandeau « mois + année » en tête de Gantt (aligné sur les mois calendaires). */
+export type GanttMonthBand = {
+  label: string
+  x0: number
+  x1: number
+  monthStartMs: number
+}
+
+export function ganttMonthBands(startMs: number, endMs: number, widthPx: number): GanttMonthBand[] {
+  const bands: GanttMonthBand[] = []
+  const cur = new Date(startMs)
+  cur.setDate(1)
+  cur.setHours(0, 0, 0, 0)
+  if (cur.getTime() > startMs) cur.setMonth(cur.getMonth() - 1)
+
+  let guard = 0
+  while (cur.getTime() < endMs && guard++ < 48) {
+    const monthStart = cur.getTime()
+    const next = new Date(cur)
+    next.setMonth(next.getMonth() + 1)
+    const monthEnd = next.getTime()
+    const x0 = msToX(Math.max(monthStart, startMs), startMs, endMs, widthPx)
+    const x1 = msToX(Math.min(monthEnd, endMs), startMs, endMs, widthPx)
+    if (x1 > x0 + 2) {
+      const label = new Date(monthStart).toLocaleDateString('fr-FR', {
+        month: 'long',
+        year: 'numeric',
+      })
+      bands.push({ label, x0, x1, monthStartMs: monthStart })
+    }
+    cur.setMonth(cur.getMonth() + 1)
+  }
+  return bands
+}
+
+export type GanttSubheaderTick = { ms: number; label: string; x: number; major: boolean }
+
+function thinSubheaderTicks(ticks: GanttSubheaderTick[], max: number): GanttSubheaderTick[] {
+  if (ticks.length <= max) return ticks
+  const step = Math.ceil(ticks.length / max)
+  return ticks.filter((_, i) => i % step === 0)
+}
+
+/**
+ * Libellés de la rangée inférieure (jours / semaines / repères mois) sous les bandeaux mensuels.
+ */
+export function ganttSubheaderTicks(
+  scale: GanttTimeScale,
+  startMs: number,
+  endMs: number,
+  widthPx: number,
+): GanttSubheaderTick[] {
+  const spanDays = Math.max(1 / 24, (endMs - startMs) / MS_DAY)
+  const maxLabels = Math.max(10, Math.min(64, Math.floor(widthPx / 48)))
+
+  if (scale === 'day') {
+    const cols = ganttDayColumns(startMs, endMs, widthPx)
+    if (cols.length === 0) return []
+    const avgW = widthPx / spanDays
+    const step =
+      avgW >= 24 ? 1 : avgW >= 15 ? 2 : avgW >= 10 ? 3 : Math.max(1, Math.ceil(cols.length / maxLabels))
+    const out: GanttSubheaderTick[] = []
+    for (let i = 0; i < cols.length; i += step) {
+      const c = cols[i]!
+      const d = new Date(c.dayStartMs)
+      const label =
+        step === 1 && avgW >= 26
+          ? d.toLocaleDateString('fr-FR', { weekday: 'short', day: 'numeric', month: 'short' })
+          : d.toLocaleDateString('fr-FR', { day: '2-digit', month: 'short' })
+      const x = (c.x0 + c.x1) / 2
+      const major = d.getDate() === 1 || d.getDay() === 1
+      out.push({ ms: c.dayStartMs, label, x, major })
+    }
+    return thinSubheaderTicks(out, maxLabels)
+  }
+
+  if (scale === 'week') {
+    const out: GanttSubheaderTick[] = []
+    let t = startOfWeekMondayLocal(startMs - 8 * MS_DAY)
+    let guard = 0
+    while (t <= endMs + MS_DAY && guard++ < 140) {
+      if (t + 6 * MS_DAY >= startMs) {
+        const d = new Date(t)
+        const label = d.toLocaleDateString('fr-FR', { day: 'numeric', month: 'short' })
+        const x = msToX(t + 3.5 * MS_DAY, startMs, endMs, widthPx)
+        out.push({ ms: t, label, x, major: true })
+      }
+      t += 7 * MS_DAY
+    }
+    return thinSubheaderTicks(out, maxLabels)
+  }
+
+  /* month */
+  const out: GanttSubheaderTick[] = []
+  const d = new Date(startMs)
+  d.setDate(1)
+  d.setHours(12, 0, 0, 0)
+  if (d.getTime() > startMs) d.setMonth(d.getMonth() - 1)
+  let g = 0
+  while (d.getTime() < endMs && g++ < 40) {
+    const y = d.getFullYear()
+    const m = d.getMonth()
+    for (const dom of [1, 8, 15, 22]) {
+      const cur = new Date(y, m, dom, 12, 0, 0, 0)
+      const ms = cur.getTime()
+      if (ms < startMs || ms > endMs) continue
+      const x = msToX(ms, startMs, endMs, widthPx)
+      out.push({
+        ms,
+        label: String(dom),
+        x,
+        major: dom === 1,
+      })
+    }
+    d.setMonth(d.getMonth() + 1)
+  }
+  return thinSubheaderTicks(out, maxLabels)
+}
+
+/** Positions X des guides verticaux (limiter le nombre quand le zoom est faible). */
+export function ganttVerticalGuideXs(
+  scale: GanttTimeScale,
+  startMs: number,
+  endMs: number,
+  widthPx: number,
+): number[] {
+  const span = Math.max(1, endMs - startMs)
+  const ppdEff = widthPx / (span / MS_DAY)
+
+  if (ppdEff >= 2.4) {
+    return ganttDayColumns(startMs, endMs, widthPx).map((c) => c.x0)
+  }
+  if (ppdEff >= 0.95 || scale === 'week') {
+    const xs: number[] = []
+    let t = startOfWeekMondayLocal(startMs - 3 * MS_DAY)
+    let guard = 0
+    while (t <= endMs + MS_DAY && guard++ < 220) {
+      xs.push(msToX(t, startMs, endMs, widthPx))
+      t += 7 * MS_DAY
+    }
+    return xs
+  }
+  return ganttMonthBands(startMs, endMs, widthPx).map((b) => b.x0)
+}
+
 export function pctOnSpan(ms: number, startMs: number, endMs: number): number {
   const span = Math.max(1, endMs - startMs)
   return ((ms - startMs) / span) * 100