Improve: stable highlight height, equation display format, responsive font sizes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app.css

@@ -79,38 +79,52 @@
 
 /* ── Highlighted result (above grid) ──────────────────────────────────────── */
 .highlighted-result {
-  text-align: center;
+  /* Fixed height that never changes whether populated or empty */
-  padding: 2rem 1rem;
+  height: 10rem;
   margin-bottom: 1.5rem;
   border-radius: var(--pico-border-radius, 0.25rem);
   background-color: var(--pico-card-background-color);
-  border: 2px solid var(--pico-primary);
+  border: 2px solid transparent; /* always present, color changes */
   box-shadow: var(--shadow-medium);
   display: flex;
   flex-direction: column;
   align-items: center;
-  gap: 0.4rem;
+  justify-content: center;
+  gap: 0.3rem;
   position: relative;
-  min-height: 8rem;
+  overflow: hidden;
+  transition: border-color 0.2s ease;
+  text-align: center;
 }
 
-.highlighted-value {
+.highlighted-result.has-highlight {
-  font-size: 2.5rem;
+  border-color: var(--pico-primary);
-  font-weight: 700;
+}
+
+.highlighted-equation-from {
+  font-size: clamp(0.85rem, 2vw, 1.1rem);
+  color: var(--color-text-muted, #888880);
   font-variant-numeric: tabular-nums;
-  line-height: 1.1;
-  word-break: break-all;
-  color: var(--pico-color);
 }
 
-.highlighted-label {
+.highlighted-equation-equals {
-  font-size: 1.25rem;
+  font-size: clamp(1.2rem, 3.5vw, 2rem);
-  color: var(--pico-color);
+  font-weight: 700;
+  color: var(--pico-primary);
+  font-variant-numeric: tabular-nums;
+  word-break: break-all;
+  text-align: center;
 }
 
 .highlighted-symbol {
+  font-size: clamp(0.75rem, 1.5vw, 0.9rem);
+  color: var(--pico-muted-color, #888880);
+  font-style: italic;
+}
+
+.highlighted-placeholder {
   font-size: 0.9rem;
-  color: var(--pico-muted-color, #666);
+  color: var(--pico-muted-color, #888880);
   font-style: italic;
 }
 
@@ -142,22 +156,18 @@
 /* ── Highlight dismiss button ──────────────────────────────────────────────── */
 .highlight-dismiss {
   position: absolute;
-  top: 0.5rem;
+  top: 0.4rem;
-  right: 0.75rem;
+  right: 0.6rem;
   background: none;
   border: none;
+  font-size: 1.1rem;
+  color: var(--pico-muted-color, #888880);
   cursor: pointer;
-  font-size: 1rem;
+  padding: 0.2rem 0.4rem;
   line-height: 1;
-  color: var(--pico-muted-color, #888);
-  padding: 0.15rem 0.3rem;
-  border-radius: 0.2rem;
-  transition: color 0.15s ease, background-color 0.15s ease;
 }
-
 .highlight-dismiss:hover {
-  color: var(--pico-color);
+  color: var(--pico-color, #2C2C2C);
-  background-color: rgba(0, 0, 0, 0.06);
 }
 
 /* ── Hotkey hint ───────────────────────────────────────────────────────────── */

src/routes/+page.svelte

@@ -6,7 +6,7 @@
   import { convertById } from '$lib/convert';
   import { FRACTIONAL_DIGITS } from '$lib/config';
   import { formatBig } from '$lib/format';
-  import type { Big } from 'big.js';
+  import Big from 'big.js';
   import type { Unit, ResultItem } from '$lib/types';
   import ConverterCard from '../components/ConverterCard.svelte';
 
@@ -60,6 +60,8 @@
       : null
   );
 
+  let fromUnit = $derived(units.find(u => u.id === fromUnitId) ?? units[0]);
+
   // ── URL sync: update URL only when serialized params actually change ────────
   $effect(() => {
     if (!browser) return;
@@ -107,16 +109,14 @@
   <title>Humor Units — Converter</title>
 </svelte:head>
 
-<div class="highlighted-result" aria-live="polite">
+<div class="highlighted-result" class:has-highlight={highlightedResult !== null} aria-live="polite">
   {#if highlightedResult !== null}
-    <button
+    <button class="highlight-dismiss" onclick={() => (highlightedUnitId = null)} aria-label="Remove highlight">×</button>
-      class="highlight-dismiss"
+    <span class="highlighted-equation-from">{formatBig(new Big(inputValue))} {fromUnit.labelPlural}</span>
-      aria-label="Remove highlight"
+    <span class="highlighted-equation-equals">= {formatBig(highlightedResult.convertedValue)} {highlightedResult.unit.labelPlural}</span>
-      onclick={() => (highlightedUnitId = null)}
-    >×</button>
-    <span class="highlighted-value">{formatBig(highlightedResult.convertedValue)}</span>
-    <span class="highlighted-label">{highlightedResult.unit.labelPlural}</span>
     <span class="highlighted-symbol">{highlightedResult.unit.symbol}</span>
+  {:else}
+    <span class="highlighted-placeholder">Click a result to highlight it</span>
   {/if}
 </div>