Show the "numolus" wordmark only when the toolbar has room for it

Instead of fixed breakpoints (wicom hidden below 720px, the wordmark below
520px -- while the toolbar already wrapped to two lines much earlier), the
wordmark and "wicom" are shown only while the whole toolbar still fits on
one line with them. Measured with a ResizeObserver; the wordmark's width is
remembered while hidden, so it doesn't flip-flop at the threshold.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/components/AppToolbar.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { computed, onBeforeUnmount, ref, watch } from 'vue';
+import { computed, onBeforeUnmount, onMounted, ref, watch } from 'vue';
 import { useDocument } from '../store/document';
 import { useTheme } from '../composables/useTheme';
 import { useToasts } from '../composables/useToasts';
@@ -32,6 +32,52 @@ const { mode: themeMode, cycle: cycleTheme } = useTheme();
 const toasts = useToasts();
 
 const fileMenuOpen = ref(false);
+
+// ---- wordmark only when there's room ----------------------------------
+// "numolus" + "wicom" next to the logo are shown only while the whole
+// toolbar still fits on one line with them; otherwise just the logo. Measured
+// rather than a fixed breakpoint, since what fits depends on the toolbar's
+// actual contents. The wordmark's own width is remembered from the last time
+// it was visible, so hiding it can't make it look like it would fit again
+// (no flip-flopping at the threshold).
+const toolbarEl = ref<HTMLElement | null>(null);
+const brandExtra = ref<HTMLElement | null>(null);
+const showWordmark = ref(true);
+let wordmarkWidth = 0;
+
+function fitWordmark() {
+  const bar = toolbarEl.value;
+  if (!bar) return;
+  const cs = getComputedStyle(bar);
+  const avail = bar.clientWidth - parseFloat(cs.paddingLeft) - parseFloat(cs.paddingRight);
+  const gap = parseFloat(cs.columnGap) || 0;
+  let need = 0;
+  let items = 0;
+  for (const child of Array.from(bar.children) as HTMLElement[]) {
+    if (getComputedStyle(child).display === 'none') continue;
+    items++;
+    if (!child.classList.contains('spacer')) need += child.getBoundingClientRect().width;
+  }
+  need += gap * Math.max(0, items - 1);
+  if (showWordmark.value && brandExtra.value) {
+    // plus the gap to the logo, which goes away with it
+    const brandGap = parseFloat(getComputedStyle(brandExtra.value.parentElement!).columnGap) || 0;
+    wordmarkWidth = brandExtra.value.getBoundingClientRect().width + brandGap;
+  } else {
+    need += wordmarkWidth;
+  }
+  showWordmark.value = need <= avail + 0.5;
+}
+
+let resizeObs: ResizeObserver | null = null;
+onMounted(() => {
+  resizeObs = new ResizeObserver(() => fitWordmark());
+  if (toolbarEl.value) resizeObs.observe(toolbarEl.value);
+  fitWordmark();
+  // web fonts arriving late change the measured widths
+  void document.fonts?.ready.then(fitWordmark);
+});
+onBeforeUnmount(() => resizeObs?.disconnect());
 const fileMenuWrap = ref<HTMLElement | null>(null);
 
 // Close the Datei menu on Escape or on a press anywhere outside it. Capture
@@ -249,13 +295,13 @@ function onSample() {
 </script>
 
 <template>
-  <header class="toolbar">
+  <header ref="toolbarEl" class="toolbar">
     <div class="brand" title="Numolus — wicom, Vaduz (FL)">
       <TheLogo class="brand-mark" />
+      <span v-show="showWordmark" ref="brandExtra" class="brand-extra">
         <span class="wordmark">numolus</span>
-      <button class="by" type="button" @click="aboutOpen = true">
-        wicom
-      </button>
+        <button class="by" type="button" @click="aboutOpen = true">wicom</button>
+      </span>
     </div>
     <button
       class="gear"
@@ -517,6 +563,11 @@ function onSample() {
   height: 24px;
   flex: none;
 }
+.brand-extra {
+  display: flex;
+  align-items: center;
+  gap: 9px;
+}
 .wordmark {
   font-size: 17px;
   font-weight: 600;
@@ -539,16 +590,6 @@ function onSample() {
 .by:hover {
   color: var(--accent);
 }
-@media (max-width: 720px) {
-  .by {
-    display: none;
-  }
-}
-@media (max-width: 520px) {
-  .wordmark {
-    display: none;
-  }
-}
 
 /* --- Über-Dialog --- */
 .about-lead {