From 7b67969774cfc678a3e9f4999b9a8fa4cacbf239 Mon Sep 17 00:00:00 2001
From: Steffen Becker <stffn.becker@gmail.com>
Date: Mon, 15 Jun 2026 15:48:15 +0200
Subject: [PATCH] feat: header/footer position

---
 src/App.svelte                          | 18 ++++-
 src/lib/editor/Editor.svelte            |  7 +-
 src/lib/editor/HeaderFooterLayer.svelte | 15 ++--
 src/lib/editor/ToolbarExpanded.svelte   | 93 ++++++++++++++++++++++++-
 src/lib/export/odt.ts                   | 35 +++++++---
 src/lib/import/odt.ts                   |  6 ++
 src/lib/import/styleResolver.ts         | 12 ++++
 src/lib/storage/headerFooter.ts         | 37 +++++++++-
 8 files changed, 197 insertions(+), 26 deletions(-)

diff --git a/src/App.svelte b/src/App.svelte
index 9e73a5a..598b4d2 100644
--- a/src/App.svelte
+++ b/src/App.svelte
@@ -10,7 +10,7 @@
   import { loadTheme, saveTheme, applyTheme, loadToolbarExpanded, saveToolbarExpanded, loadFormattingMarks, saveFormattingMarks, type ThemeMode } from './lib/storage/theme';
   import { loadPageMargins, savePageMargins, type PageMargins } from './lib/storage/pageMargins';
   import { loadOrientation, saveOrientation, type Orientation } from './lib/storage/pageOrientation';
-  import { loadHfDoc, saveHfDoc, type HfDoc, type HfZone } from './lib/storage/headerFooter';
+  import { loadHfDoc, saveHfDoc, loadHfDistances, saveHfDistances, DEFAULT_HF_DISTANCES, type HfDoc, type HfZone, type HfDistances } from './lib/storage/headerFooter';
 
   let editor: Editor | null = $state(null);
   let tick: number = $state(0);
@@ -21,6 +21,7 @@
   // top toolbars target hfEditor instead of the body editor (activeEditor below).
   let headerDoc: HfDoc = $state(loadHfDoc('header'));
   let footerDoc: HfDoc = $state(loadHfDoc('footer'));
+  let hfDistances: HfDistances = $state(loadHfDistances());
   let hfEditor: Editor | null = $state(null);
   let hfActive: HfZone | null = $state(null);
   let hfTick: number = $state(0);
@@ -56,6 +57,10 @@
     saveHfDoc('footer', footerDoc);
   });
 
+  $effect(() => {
+    saveHfDistances(hfDistances);
+  });
+
   function setZoom(value: number) {
     zoom = Math.max(20, Math.min(300, value));
     localStorage.setItem('odf-editor-zoom', String(zoom));
@@ -83,7 +88,10 @@
 
   async function handleExport() {
     if (editor) {
-      await exportToOdt(editor, pageMargins, pageOrientation, { header: headerDoc, footer: footerDoc, pageCount: numPages });
+      await exportToOdt(editor, pageMargins, pageOrientation, {
+        header: headerDoc, footer: footerDoc, pageCount: numPages,
+        headerDistanceCm: hfDistances.header, footerDistanceCm: hfDistances.footer,
+      });
     }
   }
 
@@ -112,6 +120,10 @@
       hfActive = null;
       headerDoc = result.header;
       footerDoc = result.footer;
+      hfDistances = {
+        header: result.headerDistanceCm ?? DEFAULT_HF_DISTANCES.header,
+        footer: result.footerDistanceCm ?? DEFAULT_HF_DISTANCES.footer,
+      };
 
       if (result.warnings.length) {
         console.warn('[import] Unsupported content in opened file:', result.warnings);
@@ -248,6 +260,7 @@
       bind:showFormattingMarks
       bind:pageMargins
       bind:pageOrientation
+      bind:hfDistances
       hfActive={hfActive}
       onEditZone={(zone) => (hfActive = zone)}
     />
@@ -262,6 +275,7 @@
     bind:hfEditor
     bind:hfActive
     bind:hfTick
+    {hfDistances}
     {zoom}
     {showFormattingMarks}
     {pageMargins}
diff --git a/src/lib/editor/Editor.svelte b/src/lib/editor/Editor.svelte
index 263cf9f..e6cc8e0 100644
--- a/src/lib/editor/Editor.svelte
+++ b/src/lib/editor/Editor.svelte
@@ -9,7 +9,7 @@
   import { saveDocument, loadDocument } from '../storage/autosave';
   import { applyMarginVars, DEFAULT_MARGINS, type PageMargins } from '../storage/pageMargins';
   import { applyOrientationVars, type Orientation } from '../storage/pageOrientation';
-  import type { HfDoc, HfZone } from '../storage/headerFooter';
+  import { DEFAULT_HF_DISTANCES, type HfDoc, type HfZone, type HfDistances } from '../storage/headerFooter';
   import { FORCE_PAGE_RECALC, type TableBreakBand } from './pageBreaks';
   import { recordTransaction, resetHistoryLog } from './historyLog.svelte';
   import '../../styles/editor.css';
@@ -19,12 +19,12 @@
   let {
     editor = $bindable(), tick = $bindable(0), currentPage = $bindable(1), numPages = $bindable(1),
     zoom = 100, showFormattingMarks = false, pageMargins = DEFAULT_MARGINS, orientation = 'portrait',
-    headerDoc = $bindable(null), footerDoc = $bindable(null),
+    headerDoc = $bindable(null), footerDoc = $bindable(null), hfDistances = DEFAULT_HF_DISTANCES,
     hfEditor = $bindable(null), hfActive = $bindable(null), hfTick = $bindable(0),
   }: {
     editor: Editor | null; tick: number; currentPage: number; numPages: number; zoom: number;
     showFormattingMarks?: boolean; pageMargins?: PageMargins; orientation?: Orientation;
-    headerDoc?: HfDoc; footerDoc?: HfDoc;
+    headerDoc?: HfDoc; footerDoc?: HfDoc; hfDistances?: HfDistances;
     hfEditor?: Editor | null; hfActive?: HfZone | null; hfTick?: number;
   } = $props();
 
@@ -420,6 +420,7 @@
         {currentPage}
         {pageMargins}
         {orientation}
+        {hfDistances}
       />
     </div>
   </div>
diff --git a/src/lib/editor/HeaderFooterLayer.svelte b/src/lib/editor/HeaderFooterLayer.svelte
index 2b9247a..7c8c8ef 100644
--- a/src/lib/editor/HeaderFooterLayer.svelte
+++ b/src/lib/editor/HeaderFooterLayer.svelte
@@ -1,7 +1,7 @@
 <script lang="ts">
   import { Editor, generateHTML } from '@tiptap/core';
   import { hfExtensions } from './hfExtensions';
-  import { HF_DISTANCE_CM, hfIsEmpty, type HfDoc, type HfZone } from '../storage/headerFooter';
+  import { hfIsEmpty, DEFAULT_HF_DISTANCES, type HfDoc, type HfZone, type HfDistances } from '../storage/headerFooter';
   import { cmToPx, type PageMargins } from '../storage/pageMargins';
   import { PAGE_W_PORTRAIT, PAGE_H_PORTRAIT, type Orientation } from '../storage/pageOrientation';
 
@@ -12,6 +12,7 @@
     currentPage,
     pageMargins,
     orientation,
+    hfDistances = DEFAULT_HF_DISTANCES,
     hfEditor = $bindable(),
     hfActive = $bindable(),
     hfTick = $bindable(),
@@ -22,13 +23,13 @@
     currentPage: number;
     pageMargins: PageMargins;
     orientation: Orientation;
+    hfDistances?: HfDistances;
     hfEditor: Editor | null;
     hfActive: HfZone | null;
     hfTick: number;
   } = $props();
 
   const PAGE_GAP = 20;
-  const HF_DISTANCE_PX = cmToPx(HF_DISTANCE_CM);
   // Schema for static (read-only) rendering of the inactive zones.
   const renderExts = hfExtensions();
 
@@ -42,6 +43,10 @@
   let mLeft = $derived(cmToPx(pageMargins.left));
   let mRight = $derived(cmToPx(pageMargins.right));
   let contentWidth = $derived(Math.max(0, pageWidthPx - mLeft - mRight));
+  // Edge→zone distance in px, clamped below the body margin so the zone fits within
+  // the margin band (matches the export's Math.min(dist, margin) clamp).
+  let headerDistPx = $derived(Math.min(cmToPx(hfDistances.header), mTop));
+  let footerDistPx = $derived(Math.min(cmToPx(hfDistances.footer), mBottom));
 
   let pages = $derived(Array.from({ length: Math.max(1, numPages) }, (_, i) => i + 1));
 
@@ -49,11 +54,11 @@
     const left = mLeft;
     const width = contentWidth;
     if (zone === 'header') {
-      const top = (page - 1) * cycle + HF_DISTANCE_PX;
-      return { top, left, width, height: Math.max(0, mTop - HF_DISTANCE_PX) };
+      const top = (page - 1) * cycle + headerDistPx;
+      return { top, left, width, height: Math.max(0, mTop - headerDistPx) };
     }
     const top = (page - 1) * cycle + pageHeightPx - mBottom;
-    return { top, left, width, height: Math.max(0, mBottom - HF_DISTANCE_PX) };
+    return { top, left, width, height: Math.max(0, mBottom - footerDistPx) };
   }
   const boxStyle = (b: { top: number; left: number; width: number; height: number }) =>
     `top: ${b.top}px; left: ${b.left}px; width: ${b.width}px; height: ${b.height}px;`;
diff --git a/src/lib/editor/ToolbarExpanded.svelte b/src/lib/editor/ToolbarExpanded.svelte
index 242b020..c7a238c 100644
--- a/src/lib/editor/ToolbarExpanded.svelte
+++ b/src/lib/editor/ToolbarExpanded.svelte
@@ -11,9 +11,10 @@
   } from './fontDetect';
   import { DEFAULT_MARGINS, type PageMargins } from '../storage/pageMargins';
   import type { Orientation } from '../storage/pageOrientation';
+  import { DEFAULT_HF_DISTANCES, clampHfDistance, type HfDistances } from '../storage/headerFooter';
 
-  let { editor, tick, showFormattingMarks = $bindable(), pageMargins = $bindable(DEFAULT_MARGINS), pageOrientation = $bindable<Orientation>('portrait'), hfActive = null, onEditZone }:
-    { editor: Editor | null; tick: number; showFormattingMarks: boolean; pageMargins?: PageMargins; pageOrientation?: Orientation; hfActive?: 'header' | 'footer' | null; onEditZone?: (zone: 'header' | 'footer') => void } = $props();
+  let { editor, tick, showFormattingMarks = $bindable(), pageMargins = $bindable(DEFAULT_MARGINS), pageOrientation = $bindable<Orientation>('portrait'), hfDistances = $bindable(DEFAULT_HF_DISTANCES), hfActive = null, onEditZone }:
+    { editor: Editor | null; tick: number; showFormattingMarks: boolean; pageMargins?: PageMargins; pageOrientation?: Orientation; hfDistances?: HfDistances; hfActive?: 'header' | 'footer' | null; onEditZone?: (zone: 'header' | 'footer') => void } = $props();
 
   type AlignValue = 'left' | 'center' | 'right' | 'justify';
 
@@ -606,6 +607,54 @@
     }
   }
 
+  // --- Header/footer edge distances (cm) ---
+  type HfAxis = 'header' | 'footer';
+  const HF_DIST_FIELDS: { axis: HfAxis; label: string }[] = [
+    { axis: 'header', label: 'Header from top' },
+    { axis: 'footer', label: 'Footer from bottom' },
+  ];
+  let hfDistInputs = $state<Record<HfAxis, string>>({ header: '', footer: '' });
+
+  function syncHfDistInputs() {
+    hfDistInputs = { header: fmtCm(hfDistances.header), footer: fmtCm(hfDistances.footer) };
+  }
+
+  function setHfDist(axis: HfAxis, value: number) {
+    const clamped = clampHfDistance(value);
+    hfDistances = { ...hfDistances, [axis]: clamped };
+    hfDistInputs[axis] = fmtCm(clamped);
+  }
+
+  function stepHfDist(axis: HfAxis, delta: number) {
+    setHfDist(axis, hfDistances[axis] + delta);
+  }
+
+  function commitHfDistInput(axis: HfAxis) {
+    const n = parseFloat(hfDistInputs[axis]);
+    if (Number.isNaN(n)) {
+      hfDistInputs[axis] = fmtCm(hfDistances[axis]); // revert invalid input
+      return;
+    }
+    setHfDist(axis, n);
+  }
+
+  function onHfDistKeydown(axis: HfAxis, e: KeyboardEvent) {
+    if (e.key === 'Enter') {
+      e.preventDefault();
+      commitHfDistInput(axis);
+      (e.target as HTMLInputElement).blur();
+    } else if (e.key === 'Escape') {
+      hfDistInputs[axis] = fmtCm(hfDistances[axis]);
+      (e.target as HTMLInputElement).blur();
+    } else if (e.key === 'ArrowUp') {
+      e.preventDefault();
+      stepHfDist(axis, MARGIN_STEP);
+    } else if (e.key === 'ArrowDown') {
+      e.preventDefault();
+      stepHfDist(axis, -MARGIN_STEP);
+    }
+  }
+
   function openLayout() {
     fontOpen = false;
     sizeOpen = false;
@@ -615,7 +664,10 @@
     highlightColorOpen = false;
     alignOpen = false;
     layoutOpen = !layoutOpen;
-    if (layoutOpen) syncMarginInputs();
+    if (layoutOpen) {
+      syncMarginInputs();
+      syncHfDistInputs();
+    }
   }
 
   function layoutClickOutside(node: HTMLElement) {
@@ -1072,6 +1124,38 @@
               onclick={() => onEditZone?.('footer')}
             >Edit footer</button>
           </div>
+
+          <div class="lh-section-label">Position (cm)</div>
+          <div class="margin-grid">
+            {#each HF_DIST_FIELDS as f}
+              <div class="margin-field">
+                <span class="margin-label">{f.label}</span>
+                <div class="margin-input-wrap">
+                  <input
+                    type="text"
+                    class="margin-input"
+                    bind:value={hfDistInputs[f.axis]}
+                    onkeydown={(e) => onHfDistKeydown(f.axis, e)}
+                    onblur={() => commitHfDistInput(f.axis)}
+                    inputmode="decimal"
+                    title="{f.label} (cm)"
+                  />
+                  <div class="margin-steppers">
+                    <button class="margin-step" tabindex="-1" onclick={() => stepHfDist(f.axis, MARGIN_STEP)} title="Increase" aria-label="Increase {f.label.toLowerCase()}">
+                      <svg width="8" height="8" viewBox="0 0 8 8" fill="none" aria-hidden="true">
+                        <path d="M1 5.5l3-3 3 3" stroke="currentColor" stroke-width="1.4" stroke-linecap="round" stroke-linejoin="round"/>
+                      </svg>
+                    </button>
+                    <button class="margin-step" tabindex="-1" onclick={() => stepHfDist(f.axis, -MARGIN_STEP)} title="Decrease" aria-label="Decrease {f.label.toLowerCase()}">
+                      <svg width="8" height="8" viewBox="0 0 8 8" fill="none" aria-hidden="true">
+                        <path d="M1 2.5l3 3 3-3" stroke="currentColor" stroke-width="1.4" stroke-linecap="round" stroke-linejoin="round"/>
+                      </svg>
+                    </button>
+                  </div>
+                </div>
+              </div>
+            {/each}
+          </div>
         </div>
       {/if}
     </div>
@@ -1570,6 +1654,9 @@
   .margin-input-wrap {
     display: flex;
     align-items: stretch;
+    /* Pin the input to the bottom of its grid cell so a wrapped two-line label
+       (e.g. "Footer from bottom") doesn't push its box below the sibling's. */
+    margin-top: auto;
     height: 1.9rem;
     border: 1px solid var(--color-border);
     border-radius: var(--radius);
diff --git a/src/lib/export/odt.ts b/src/lib/export/odt.ts
index 2b997a8..f7daa6c 100644
--- a/src/lib/export/odt.ts
+++ b/src/lib/export/odt.ts
@@ -872,15 +872,26 @@ function applyLineBreaks(odtBytes: Uint8Array): Uint8Array {
   return rezipOdt(files);
 }
 
-// Header/footer input for the export: one single-paragraph doc per zone (or null)
-// plus the page count snapshot used as the stored <text:page-count> value.
-export type HfExport = { header: HfDoc; footer: HfDoc; pageCount: number };
+// Header/footer input for the export: one single-paragraph doc per zone (or null),
+// the page count snapshot for the stored <text:page-count> value, and the page-edge
+// distances (cm; default HF_DISTANCE_CM) for header (from top) / footer (from bottom).
+export type HfExport = {
+  header: HfDoc;
+  footer: HfDoc;
+  pageCount: number;
+  headerDistanceCm?: number;
+  footerDistanceCm?: number;
+};
 
 // The full document → .odt pipeline, DOM-free (exportToOdt adds the download).
 export async function buildOdt(docJson: TiptapNode, margins: PageMargins = DEFAULT_MARGINS, orientation: Orientation = 'portrait', hf?: HfExport): Promise<Uint8Array> {
   const raw = replaceHardBreaks(docJson);
   const headerPara = hf && !hfIsEmpty(hf.header) ? (hf.header!.content![0] as TiptapNode) : null;
   const footerPara = hf && !hfIsEmpty(hf.footer) ? (hf.footer!.content![0] as TiptapNode) : null;
+  // Distance from the page edge to the header (top) / footer (bottom). Becomes the
+  // ODF page margin; clamped below the body margin so the body still starts at it.
+  const headerDist = Math.min(hf?.headerDistanceCm ?? HF_DISTANCE_CM, margins.top);
+  const footerDist = Math.min(hf?.footerDistanceCm ?? HF_DISTANCE_CM, margins.bottom);
   let json = injectCustomTypes(raw);
   if (headerPara || footerPara) {
     json = { ...json, content: [{ type: CUST_HF }, ...(json.content ?? [])] };
@@ -904,8 +915,8 @@ export async function buildOdt(docJson: TiptapNode, margins: PageMargins = DEFAU
     // With a header/footer, ODF's vertical margin is the page-edge→header distance;
     // applyHfPostProcess sizes the header box so the body still starts at the
     // editor's margin (Word-style mapping).
-    marginTop: `${headerPara ? HF_DISTANCE_CM : margins.top}cm`,
-    marginBottom: `${footerPara ? HF_DISTANCE_CM : margins.bottom}cm`,
+    marginTop: `${headerPara ? headerDist : margins.top}cm`,
+    marginBottom: `${footerPara ? footerDist : margins.bottom}cm`,
     marginLeft: `${margins.left}cm`,
     marginRight: `${margins.right}cm`,
     unknownNodeHandler(node: TiptapNode, doc: OdtDocument) {
@@ -978,7 +989,7 @@ export async function buildOdt(docJson: TiptapNode, margins: PageMargins = DEFAU
   const cleaned = collapseRunWhitespace(styledRows);
   const withBreaks = applyLineBreaks(cleaned);
   const withStyles = rewriteStylesXml(withBreaks);
-  return applyHfPostProcess(withStyles, margins, headerPara, footerPara);
+  return applyHfPostProcess(withStyles, margins, headerPara, footerPara, headerDist, footerDist);
 }
 
 function hfAlign(para: TiptapNode): AlignValue | null {
@@ -991,7 +1002,7 @@ function hfAlign(para: TiptapNode): AlignValue | null {
 // Word-style mapping (page margin = HF distance, min-height fills up to the body
 // margin so the body starts exactly at the editor's margin), and apply the
 // paragraph alignment to the named Header/Footer styles.
-function applyHfPostProcess(odtBytes: Uint8Array, margins: PageMargins, headerPara: TiptapNode | null, footerPara: TiptapNode | null): Uint8Array {
+function applyHfPostProcess(odtBytes: Uint8Array, margins: PageMargins, headerPara: TiptapNode | null, footerPara: TiptapNode | null, headerDist: number, footerDist: number): Uint8Array {
   if (!headerPara && !footerPara) return odtBytes;
 
   const files = unzipSync(odtBytes);
@@ -1006,8 +1017,10 @@ function applyHfPostProcess(odtBytes: Uint8Array, margins: PageMargins, headerPa
   styles = styles.replace(new RegExp(`${PGC}(\\d*)${PGC}`, 'g'), '<text:page-count>$1</text:page-count>');
 
   const round3 = (v: number) => Math.round(v * 1000) / 1000;
-  const zone = (kind: 'header' | 'footer', para: TiptapNode, bodyMarginCm: number) => {
-    const minH = round3(Math.max(0.2, bodyMarginCm - HF_DISTANCE_CM));
+  const zone = (kind: 'header' | 'footer', para: TiptapNode, bodyMarginCm: number, distCm: number) => {
+    // min-height fills the gap between the edge→zone distance and the body margin,
+    // so the body still starts at bodyMarginCm (page margin was set to distCm).
+    const minH = round3(Math.max(0.2, bodyMarginCm - distCm));
     // The spacing attr sits on the body-facing side: below the header, above the footer.
     const spacingAttr = kind === 'header' ? 'fo:margin-bottom' : 'fo:margin-top';
     styles = styles.replace(
@@ -1023,8 +1036,8 @@ function applyHfPostProcess(odtBytes: Uint8Array, margins: PageMargins, headerPa
       );
     }
   };
-  if (headerPara) zone('header', headerPara, margins.top);
-  if (footerPara) zone('footer', footerPara, margins.bottom);
+  if (headerPara) zone('header', headerPara, margins.top, headerDist);
+  if (footerPara) zone('footer', footerPara, margins.bottom, footerDist);
 
   files['styles.xml'] = strToU8(styles);
   return rezipOdt(files);
diff --git a/src/lib/import/odt.ts b/src/lib/import/odt.ts
index 4eb487b..91335fe 100644
--- a/src/lib/import/odt.ts
+++ b/src/lib/import/odt.ts
@@ -26,6 +26,9 @@ export interface OdtImportResult {
   // Single-paragraph docs in the hfExtensions schema; null = no zone.
   header: Node | null;
   footer: Node | null;
+  // Edge→zone distance (cm): header from top, footer from bottom. null = no zone.
+  headerDistanceCm: number | null;
+  footerDistanceCm: number | null;
   warnings: string[];
 }
 
@@ -87,12 +90,15 @@ export function importOdt(bytes: Uint8Array): OdtImportResult {
   }
 
   const geometry = resolver.pageGeometry();
+  const edge = resolver.edgeDistancesCm();
   return {
     content: { type: 'doc', content: blocks },
     margins: geometry?.margins ?? null,
     orientation: geometry?.orientation ?? null,
     header: hf.header ? convertHfZone(hf.header, ctx) : null,
     footer: hf.footer ? convertHfZone(hf.footer, ctx) : null,
+    headerDistanceCm: hf.header ? edge?.top ?? null : null,
+    footerDistanceCm: hf.footer ? edge?.bottom ?? null : null,
     warnings: [...warnings],
   };
 }
diff --git a/src/lib/import/styleResolver.ts b/src/lib/import/styleResolver.ts
index e4e756b..68e8b19 100644
--- a/src/lib/import/styleResolver.ts
+++ b/src/lib/import/styleResolver.ts
@@ -319,4 +319,16 @@ export class StyleResolver {
     const orientation: Orientation = w != null && h != null && w > h ? 'landscape' : 'portrait';
     return { margins, orientation };
   }
+
+  // Raw page margins (cm) = ODF's edge→zone distance, i.e. the header distance from
+  // the top and footer distance from the bottom when a header/footer is present.
+  edgeDistancesCm(): { top: number; bottom: number } | null {
+    const props = this.pageLayoutEl()?.getElementsByTagNameNS(NS.style, 'page-layout-properties')[0] ?? null;
+    if (!props) return null;
+    const cm = (attr: string) => {
+      const v = lengthToCm(props.getAttributeNS(NS.fo, attr));
+      return v == null ? null : Math.min(10, Math.max(0, Math.round(v * 100) / 100));
+    };
+    return { top: cm('margin-top') ?? 1.25, bottom: cm('margin-bottom') ?? 1.25 };
+  }
 }
diff --git a/src/lib/storage/headerFooter.ts b/src/lib/storage/headerFooter.ts
index fadd493..6a86926 100644
--- a/src/lib/storage/headerFooter.ts
+++ b/src/lib/storage/headerFooter.ts
@@ -11,8 +11,41 @@ const KEYS: Record<HfZone, string> = {
 
 // Word's default distance from the page edge to the header/footer text. The body
 // margin stays the body margin (Word semantics); export/import convert to ODF's
-// margin-to-header model (see export/odt.ts applyHeaderFooterGeometry).
-export const HF_DISTANCE_CM = 1.27;
+// margin-to-header model (see export/odt.ts applyHfPostProcess).
+export const HF_DISTANCE_CM = 1.25;
+
+// Per-zone distance from the page edge to the header (from top) / footer (from
+// bottom), in cm — user-configurable in the Layout panel.
+export type HfDistances = { header: number; footer: number };
+
+export const DEFAULT_HF_DISTANCES: HfDistances = { header: HF_DISTANCE_CM, footer: HF_DISTANCE_CM };
+
+const DIST_KEY = 'odf-editor-hf-distances';
+const DIST_MIN = 0;
+const DIST_MAX = 10;
+
+export function clampHfDistance(n: number): number {
+  if (!Number.isFinite(n)) return HF_DISTANCE_CM;
+  return Math.min(DIST_MAX, Math.max(DIST_MIN, Math.round(n * 100) / 100));
+}
+
+export function loadHfDistances(): HfDistances {
+  const raw = localStorage.getItem(DIST_KEY);
+  if (!raw) return { ...DEFAULT_HF_DISTANCES };
+  try {
+    const p = JSON.parse(raw);
+    return {
+      header: typeof p.header === 'number' ? clampHfDistance(p.header) : HF_DISTANCE_CM,
+      footer: typeof p.footer === 'number' ? clampHfDistance(p.footer) : HF_DISTANCE_CM,
+    };
+  } catch {
+    return { ...DEFAULT_HF_DISTANCES };
+  }
+}
+
+export function saveHfDistances(d: HfDistances): void {
+  localStorage.setItem(DIST_KEY, JSON.stringify(d));
+}
 
 export function loadHfDoc(zone: HfZone): HfDoc {
   const raw = localStorage.getItem(KEYS[zone]);