feat: responsive mobile layout for monitoring dashboard

Redesign the UI to work on mobile/portrait viewports using CSS media
queries at max-width 768px:

- Host rows stack vertically: info (name, latency, status) on top,
  sparkline chart full-width below
- Summary stats line wraps properly with hidden pipe separators
- Header stacks title and controls vertically
- Pause button and controls sized appropriately for touch
- Pin button repositioned for mobile touch targets
- Footer legend wraps cleanly

Desktop layout remains pixel-identical — all changes are scoped to the
@media (max-width: 768px) query in styles.css only.

Refs #2

src/main.js

@@ -551,9 +551,9 @@ function hostRowHTML(host, index, showPin = true) {
         : `<div class="flex-shrink-0 w-4 h-4"></div>`;
     return `
     <div class="host-row bg-gray-800/50 rounded-lg p-2 border border-gray-700/50" data-index="${index}">
-      <div class="host-row-inner flex items-center gap-4 min-w-0">
+      <div class="flex items-center gap-4 min-w-0">
         ${pinBtn}
-        <div class="host-info-panel w-[420px] flex-shrink-0 grid grid-cols-[minmax(0,1fr)_auto] items-center">
+        <div class="w-[420px] flex-shrink-0 grid grid-cols-[minmax(0,1fr)_auto] items-center">
           <div class="flex items-center gap-2 min-w-[200px]">
             <div class="w-3 h-3 rounded-full flex-shrink-0" style="background-color: ${latencyHex(null)}"></div>
             <span class="font-medium text-white truncate">${host.name}</span>
@@ -589,9 +589,9 @@ function buildUI(state) {
     app.innerHTML = `
     <div class="mx-auto px-[5%] py-8">
       <header class="mb-8">
-        <div class="header-top flex items-center justify-between mb-4">
+        <div class="flex items-center justify-between mb-4">
           <h1 class="text-3xl font-bold text-white"><a href="https://git.eeqj.de/sneak/netwatch" target="_blank" rel="noopener" class="underline decoration-dashed decoration-gray-500 underline-offset-4">NetWatch</a> by <a href="https://sneak.berlin" target="_blank" rel="noopener" class="text-blue-400 underline hover:text-blue-300">@sneak</a></h1>
-          <div class="header-controls flex flex-col items-end gap-2">
+          <div class="flex flex-col items-end gap-2">
             <button id="pause-btn"
               class="flex items-center gap-3 px-6 py-3 bg-gray-800 hover:bg-gray-700 border border-gray-600 rounded-lg transition-colors focus:outline-none focus:ring-2 focus:ring-blue-500">
               <svg id="pause-icon" class="w-8 h-8 text-yellow-400" fill="currentColor" viewBox="0 0 24 24">

src/styles.css

@@ -22,53 +22,95 @@ body {
     );
 }
 
-/* Mobile-responsive host rows */
+/* ---- Mobile responsive layout (portrait / narrow viewports) ---- */
 @media (max-width: 768px) {
-    .host-row-inner {
+    /* Header: stack title and controls vertically */
-        flex-direction: column !important;
+    header .flex.items-center.justify-between {
-        align-items: stretch !important;
+        flex-direction: column;
-        gap: 0.5rem !important;
+        align-items: flex-start !important;
+        gap: 1rem;
     }
 
-    .host-row-inner .pin-btn {
+    header .flex.flex-col.items-end {
-        align-self: flex-end;
+        align-items: flex-start !important;
+        flex-direction: row;
+        flex-wrap: wrap;
+        gap: 0.75rem;
     }
 
-    .host-info-panel {
+    /* Pause button: smaller on mobile */
-        width: 100% !important;
+    #pause-btn {
+        padding: 0.5rem 1rem;
     }
 
-    .host-row .sparkline-container {
+    #pause-btn svg {
-        width: 100% !important;
+        width: 1.25rem;
-        flex-shrink: 0;
+        height: 1.25rem;
     }
 
-    /* Summary line: allow wrapping */
+    #pause-text {
+        font-size: 0.875rem;
+    }
+
+    /* Summary box: wrap into a grid for readability */
     #summary {
-        display: flex !important;
+        display: flex;
-        flex-wrap: wrap !important;
+        flex-wrap: wrap;
-        gap: 0.25rem 0.5rem !important;
+        gap: 0.25rem 0.5rem;
-        justify-content: center !important;
+        justify-content: center;
+        line-height: 1.6;
     }
 
+    /* Hide the pipe separators on mobile */
     #summary .text-gray-600.mx-3 {
         display: none;
     }
 
-    /* Header: stack controls below title */
+    /* Host row: stack vertically */
-    .header-top {
+    .host-row .flex.items-center.gap-4 {
-        flex-direction: column !important;
+        flex-direction: column;
-        align-items: flex-start !important;
+        align-items: stretch !important;
-        gap: 1rem !important;
+        gap: 0.5rem;
     }
 
-    .header-controls {
+    /* Info section: full width, remove fixed width */
-        align-items: flex-start !important;
+    .host-row .w-\[420px\] {
-        width: 100%;
+        width: 100% !important;
+        display: grid;
+        grid-template-columns: 1fr auto;
+        align-items: center;
     }
 
-    #pause-btn {
+    /* Host name row with dot */
+    .host-row .flex.items-center.gap-2.min-w-\[200px\] {
+        min-width: 0;
+    }
+
+    /* Latency value: slightly smaller on mobile */
+    .host-row .latency-value {
+        font-size: 1.875rem;
+        line-height: 2.25rem;
+    }
+
+    /* Sparkline: full width below the info */
+    .host-row .sparkline-container {
         width: 100%;
-        justify-content: center;
+        flex-shrink: 0;
+    }
+
+    /* Pin button: inline with the host info */
+    .host-row .pin-btn {
+        position: absolute;
+        right: 0.5rem;
+        top: 0.5rem;
+    }
+
+    .host-row {
+        position: relative;
+    }
+
+    /* Footer legend: wrap nicely */
+    footer p {
+        line-height: 1.8;
     }
 }