diff --git a/internal/control/ui.html b/internal/control/ui.html
index f7fc80a..792962b 100644
--- a/internal/control/ui.html
+++ b/internal/control/ui.html
@@ -5,63 +5,52 @@
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>fm-rds-tx</title>
 <style>
-@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@400;600;700&family=Archivo+Black&display=swap');
+@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&family=JetBrains+Mono:wght@400;600&display=swap');
 
 :root {
-  --bg: #0a0a0c;
-  --bg-2: #0f1015;
-  --surface: #111116;
-  --surface2: #18181e;
-  --surface3: #1f2028;
-  --border: #2a2a35;
-  --border-strong: #3a3a49;
-  --text: #d4d4dc;
-  --text-dim: #8b8b99;
-  --text-muted: #666674;
-  --accent: #ff3b30;
-  --accent-glow: #ff3b3044;
-  --green: #30d158;
-  --green-glow: #30d15844;
-  --amber: #ff9f0a;
-  --amber-glow: #ff9f0a44;
-  --blue: #0a84ff;
-  --blue-glow: #0a84ff33;
+  --bg: #f7f8fb;
+  --bg-2: #eef0f3;
+  --surface: #ffffff;
+  --surface2: #f4f6f8;
+  --surface3: #e8ecf1;
+  --border: #d7dcdf;
+  --border-strong: #bcc5ce;
+  --text: #111724;
+  --text-dim: #4c5a6a;
+  --text-muted: #6b7683;
+  --accent: #1f4d9d;
+  --accent-soft: rgba(31, 77, 157, 0.08);
+  --green: #0d944a;
+  --green-soft: rgba(13, 148, 74, 0.1);
+  --amber: #b7791f;
+  --amber-soft: rgba(183, 121, 31, 0.12);
+  --red: #b03030;
+  --red-soft: rgba(176, 48, 48, 0.1);
   --mono: 'JetBrains Mono', monospace;
-  --display: 'Archivo Black', sans-serif;
+  --display: 'Inter', sans-serif;
   --radius: 8px;
-  --shadow: 0 10px 30px rgba(0,0,0,.25);
+  --shadow: 0 8px 24px rgba(15,23,42,0.08);
 }
 
 * { box-sizing: border-box; margin: 0; padding: 0; }
-html { color-scheme: dark; }
+html { color-scheme: light; }
 body {
-  background:
-    radial-gradient(circle at top right, rgba(10,132,255,.06), transparent 28%),
-    radial-gradient(circle at top left, rgba(255,59,48,.06), transparent 30%),
-    var(--bg);
+  background: linear-gradient(180deg, #fbfcfe 0%, var(--bg) 100%);
   color: var(--text);
-  font-family: var(--mono);
-  font-size: 13px;
+  font-family: var(--display);
+  font-size: 14px;
   line-height: 1.5;
   min-height: 100vh;
   overflow-x: hidden;
 }
 
-body::before {
-  content: '';
-  position: fixed; inset: 0;
-  background: repeating-linear-gradient(0deg, transparent, transparent 2px, rgba(255,255,255,0.015) 2px, rgba(255,255,255,0.015) 4px);
-  pointer-events: none;
-  z-index: 1000;
-}
-
 button, input { font: inherit; }
 button { user-select: none; }
 
 .app {
-  max-width: 1120px;
+  max-width: 1200px;
   margin: 0 auto;
-  padding: 18px;
+  padding: 24px;
 }
 
 .header {
@@ -69,9 +58,9 @@ button { user-select: none; }
   align-items: flex-start;
   justify-content: space-between;
   gap: 18px;
-  padding: 8px 0 22px;
+  padding: 4px 0 20px;
   border-bottom: 1px solid var(--border);
-  margin-bottom: 18px;
+  margin-bottom: 20px;
 }
 .header-main {
   display: flex;
@@ -80,11 +69,15 @@ button { user-select: none; }
 }
 .header h1 {
   font-family: var(--display);
-  font-size: 24px;
-  letter-spacing: 2px;
-  text-transform: uppercase;
-  color: var(--accent);
-  text-shadow: 0 0 20px var(--accent-glow), 0 0 40px var(--accent-glow);
+  font-size: 28px;
+  font-weight: 800;
+  letter-spacing: -0.03em;
+  text-transform: none;
+  color: var(--text);
+}
+.header-note {
+  font-size: 13px;
+  color: var(--text-muted);
 }
 .header-sub {
   display: flex;
@@ -99,11 +92,11 @@ button { user-select: none; }
   padding: 0 10px;
   border: 1px solid var(--border);
   border-radius: 999px;
-  background: rgba(255,255,255,0.02);
+  background: var(--surface2);
   color: var(--text-dim);
   font-size: 11px;
   text-transform: uppercase;
-  letter-spacing: .8px;
+  letter-spacing: .08em;
 }
 .badge strong {
   color: var(--text);
@@ -127,50 +120,56 @@ button { user-select: none; }
 }
 .led.on-green {
   background: var(--green);
-  box-shadow: 0 0 10px rgba(46, 125, 50, 0.45);
+  box-shadow: 0 0 0 3px rgba(13,148,74,0.16);
 }
 .led.on-red {
-  background: var(--accent);
-  box-shadow: 0 0 10px rgba(180, 35, 24, 0.45);
+  background: var(--red);
+  box-shadow: 0 0 0 3px rgba(176,48,48,0.14);
 }
 .led.on-amber {
   background: var(--amber);
-  box-shadow: 0 0 10px rgba(178, 106, 0, 0.45);
+  box-shadow: 0 0 0 3px rgba(183,121,31,0.14);
 }
 .led.on-blue {
-  background: var(--blue);
-  box-shadow: 0 0 10px rgba(41, 98, 179, 0.45);
+  background: var(--accent);
+  box-shadow: 0 0 0 3px rgba(31,77,157,0.14);
 }
 
 .status-text {
   font-size: 10px;
   color: var(--text-dim);
   text-transform: uppercase;
-  letter-spacing: 1.2px;
+  letter-spacing: .08em;
 }
 
 .tab-bar {
   display: flex;
-  gap: 10px;
+  gap: 6px;
   border-bottom: 1px solid var(--border);
-  padding-bottom: 10px;
-  margin: 0 -24px 18px;
+  padding-bottom: 0;
+  margin: 0 0 20px;
   flex-wrap: wrap;
+  position: sticky;
+  top: 0;
+  background: rgba(247,248,251,.92);
+  backdrop-filter: blur(8px);
+  z-index: 10;
 }
 .tab-btn {
-  border: 1px solid var(--border);
-  border-radius: var(--radius);
+  border: none;
+  border-bottom: 3px solid transparent;
+  border-radius: 0;
   background: transparent;
   color: var(--text-dim);
-  font-size: 12px;
-  font-weight: 600;
-  padding: 8px 18px;
+  font-size: 13px;
+  font-weight: 700;
+  padding: 12px 16px 11px;
   cursor: pointer;
-  transition: all .16s ease;
+  transition: color .16s ease, border-color .16s ease, background-color .16s ease;
 }
 .tab-btn.active {
-  border-color: var(--accent);
-  background: var(--surface);
+  border-bottom-color: var(--accent);
+  background: transparent;
   color: var(--accent);
 }
 .tab-btn:focus-visible {
@@ -212,10 +211,6 @@ button { user-select: none; }
 .hero {
   padding: 16px;
 }
-@keyframes blinkSoft {
-  0%, 100% { opacity: 1; }
-  50% { opacity: .55; }
-}
 
 .tx-bar {
   position: relative;
@@ -234,16 +229,16 @@ button { user-select: none; }
 .freq-display-label {
   font-size: 10px;
   text-transform: uppercase;
-  letter-spacing: 1.4px;
+  letter-spacing: .08em;
   color: var(--text-dim);
 }
 .freq-display {
   font-family: var(--display);
-  font-size: 38px;
+  font-size: 40px;
   color: var(--text);
-  letter-spacing: 0.6px;
+  letter-spacing: -0.04em;
   line-height: 1;
-  font-weight: 600;
+  font-weight: 800;
 }
 .freq-display .unit {
   font-family: var(--mono);
@@ -259,7 +254,7 @@ button { user-select: none; }
   font-size: 11px;
   color: var(--text-muted);
   text-transform: uppercase;
-  letter-spacing: 1px;
+  letter-spacing: .08em;
 }
 .freq-note-item {
   display: inline-flex;
@@ -287,7 +282,7 @@ button { user-select: none; }
   font-size: 12px;
   font-weight: 700;
   text-transform: uppercase;
-  letter-spacing: 1px;
+  letter-spacing: .08em;
   transition: all .16s ease;
 }
 .tx-btn:hover, .ghost-btn:hover, .apply-btn:hover, .preset-btn:hover, .danger-btn:hover {
@@ -299,18 +294,18 @@ button { user-select: none; }
   cursor: not-allowed;
   transform: none;
 }
-.tx-btn.start { border-color: var(--green); color: var(--green); }
-.tx-btn.start:hover:not(:disabled) { background: rgba(48,209,88,.1); }
-.tx-btn.stop { border-color: var(--accent); color: var(--accent); }
-.tx-btn.stop:hover:not(:disabled) { background: rgba(255,59,48,.1); }
+.tx-btn.start { background: var(--green); color: #fff; border-color: transparent; }
+.tx-btn.start:hover:not(:disabled) { background: #0b7f40; }
+.tx-btn.stop { background: #fff; color: var(--red); border-color: rgba(176,48,48,.35); }
+.tx-btn.stop:hover:not(:disabled) { background: var(--red-soft); }
 .ghost-btn { color: var(--text-dim); }
 .danger-btn {
-  border-color: rgba(255,59,48,.45);
-  color: var(--accent);
-  background: rgba(255,59,48,.04);
+  border-color: rgba(176,48,48,.35);
+  color: var(--red);
+  background: var(--red-soft);
 }
 .danger-btn:hover:not(:disabled) {
-  background: rgba(255,59,48,.12);
+  background: rgba(176,48,48,.16);
 }
 
 .tx-state-wrap {
@@ -325,10 +320,10 @@ button { user-select: none; }
   letter-spacing: 2px;
   color: var(--text-dim);
 }
-.tx-state.running { color: var(--green); animation: blinkSoft 2s ease-in-out infinite; }
+.tx-state.running { color: var(--green); }
 .tx-state.idle, .tx-state.stopped { color: var(--text-dim); }
-.tx-state.starting, .tx-state.stopping, .tx-state.working { color: var(--amber); animation: blinkSoft 1.1s ease-in-out infinite; }
-.tx-state.error { color: var(--accent); }
+.tx-state.starting, .tx-state.stopping, .tx-state.working { color: var(--amber); }
+.tx-state.error { color: var(--red); }
 .status-hint {
   font-size: 10px;
   color: var(--text-muted);
@@ -347,12 +342,12 @@ button { user-select: none; }
   padding: 12px;
   border: 1px solid var(--border);
   border-radius: var(--radius);
-  background: var(--bg-2);
+  background: var(--surface2);
 }
 .quick-item .label {
   font-size: 9px;
   text-transform: uppercase;
-  letter-spacing: 1.4px;
+  letter-spacing: .08em;
   color: var(--text-dim);
   margin-bottom: 6px;
 }
@@ -377,7 +372,7 @@ button { user-select: none; }
   padding: 12px;
   border: 1px solid var(--border);
   border-radius: var(--radius);
-  background: var(--bg-2);
+  background: var(--surface2);
 }
 .signal-head {
   display: flex;
@@ -390,7 +385,7 @@ button { user-select: none; }
   font-size: 10px;
   color: var(--text-dim);
   text-transform: uppercase;
-  letter-spacing: 1.2px;
+  letter-spacing: .08em;
 }
 .signal-value {
   font-size: 11px;
@@ -401,7 +396,7 @@ button { user-select: none; }
   width: 100%;
   height: 10px;
   border-radius: 999px;
-  background: #171821;
+  background: #e7ebf0;
   border: 1px solid var(--border);
   overflow: hidden;
 }
@@ -409,21 +404,21 @@ button { user-select: none; }
   height: 100%;
   width: 0%;
   transition: width .25s ease, background-color .25s ease;
-  background: linear-gradient(90deg, var(--green), #5cff90);
+  background: linear-gradient(90deg, var(--green), #3dbd75);
 }
 .meter-fill.warn {
-  background: linear-gradient(90deg, var(--amber), #ffc45b);
+  background: linear-gradient(90deg, var(--amber), #d9a14a);
 }
 .meter-fill.err {
-  background: linear-gradient(90deg, var(--accent), #ff6b63);
+  background: linear-gradient(90deg, var(--red), #d85c5c);
 }
 .spark {
   width: 100%;
   height: 34px;
   margin-top: 10px;
   border-radius: 6px;
-  background: rgba(255,255,255,0.01);
-  border: 1px solid rgba(255,255,255,0.03);
+  background: #f7f9fb;
+  border: 1px solid #e3e8ee;
 }
 .spark path.line {
   fill: none;
@@ -494,7 +489,7 @@ button { user-select: none; }
   justify-content: space-between;
   gap: 12px;
   padding: 7px 0;
-  border-bottom: 1px solid #1a1a22;
+  border-bottom: 1px solid #e6eaef;
 }
 .shortcut-line:last-child { border-bottom: none; }
 .shortcut-line .name { font-size: 11px; color: var(--text-dim); }
@@ -509,7 +504,7 @@ button { user-select: none; }
   border: 1px solid var(--border);
   border-bottom-width: 2px;
   border-radius: 6px;
-  background: var(--bg-2);
+  background: var(--surface2);
   font-size: 10px;
   color: var(--text);
   text-align: center;
@@ -525,13 +520,13 @@ button { user-select: none; }
   min-height: 34px;
   padding: 0 12px;
   font-size: 11px;
-  letter-spacing: .8px;
+  letter-spacing: .08em;
   color: var(--text-dim);
 }
 .preset-btn.active {
-  border-color: var(--blue);
-  color: var(--blue);
-  background: rgba(10,132,255,.08);
+  border-color: var(--accent);
+  color: var(--accent);
+  background: var(--accent-soft);
 }
 .preset-btn.rds {
   text-transform: none;
@@ -543,7 +538,7 @@ button { user-select: none; }
   align-items: center;
   gap: 12px;
   padding: 10px 0;
-  border-bottom: 1px solid #1a1a22;
+  border-bottom: 1px solid #e6eaef;
 }
 .ctrl-row:last-child { border-bottom: none; }
 .ctrl-label-wrap {
@@ -593,7 +588,7 @@ input[type="range"]::-webkit-slider-thumb:hover {
   transform: scale(1.06);
 }
 input[type="number"], input[type="text"] {
-  background: var(--bg);
+  background: #fff;
   border: 1px solid var(--border);
   border-radius: 6px;
   color: var(--text);
@@ -608,16 +603,16 @@ input[type="number"] {
 input[type="text"] { width: 100%; }
 input:focus {
   border-color: var(--accent);
-  box-shadow: 0 0 0 3px rgba(255,59,48,.12);
+  box-shadow: 0 0 0 3px rgba(31,77,157,.12);
 }
 input.input-dirty {
   border-color: var(--amber);
-  box-shadow: 0 0 0 3px rgba(255,159,10,.08);
+  box-shadow: 0 0 0 3px rgba(183,121,31,.08);
 }
 input.input-error {
-  border-color: var(--accent);
-  box-shadow: 0 0 0 3px rgba(255,59,48,.14);
-  background: rgba(255,59,48,.04);
+  border-color: var(--red);
+  box-shadow: 0 0 0 3px rgba(176,48,48,.14);
+  background: rgba(176,48,48,.04);
 }
 .val-display {
   min-width: 64px;
@@ -711,10 +706,10 @@ input.input-error {
 }
 .rds-input {
   width: 100%;
-  background: var(--bg);
+  background: #fff;
   border: 1px solid var(--border);
   border-radius: 6px;
-  color: var(--green);
+  color: var(--accent);
   font-family: var(--mono);
   font-size: 15px;
   font-weight: 700;
@@ -765,7 +760,7 @@ input.input-error {
 .sidebar-title {
   font-size: 11px;
   text-transform: uppercase;
-  letter-spacing: 1.4px;
+  letter-spacing: .08em;
   color: var(--text-dim);
   margin-bottom: 10px;
 }
@@ -779,7 +774,7 @@ input.input-error {
   font-size: 10px;
   color: var(--text-muted);
   text-transform: uppercase;
-  letter-spacing: 1px;
+  letter-spacing: .08em;
 }
 .kv .v {
   font-size: 12px;
@@ -813,7 +808,7 @@ input.input-error {
 .health-trend-label {
   font-size: 10px;
   text-transform: uppercase;
-  letter-spacing: 1px;
+  letter-spacing: .08em;
   color: var(--text-muted);
   margin-bottom: 6px;
 }
@@ -823,7 +818,7 @@ input.input-error {
   padding: 10px;
   border: 1px solid var(--border);
   border-radius: 6px;
-  background: var(--surface1);
+  background: #fbfcfd;
   font-size: 11px;
   max-height: 180px;
   overflow-y: auto;
@@ -902,11 +897,11 @@ input.input-error {
 }
 
 .log {
-  background: var(--bg);
+  background: #fbfcfd;
   border: 1px solid var(--border);
   border-radius: 6px;
   padding: 10px;
-  font-size: 10px;
+  font-size: 11px;
   color: var(--text-dim);
   max-height: 220px;
   overflow-y: auto;
@@ -995,7 +990,8 @@ input.input-error {
 <div class="app">
   <div class="header">
     <div class="header-main">
-      <h1>FM-RDS-TX</h1>
+      <h1>FM-RDS-TX Control Plane</h1>
+      <div class="header-note">Overview first, controls second, diagnostics when needed.</div>
       <div class="header-sub">
         <div class="badge"><span>Backend</span><strong id="badge-backend">--</strong></div>
         <div class="badge"><span>Mode</span><strong id="badge-mode">Control Plane</strong></div>
@@ -1011,9 +1007,9 @@ input.input-error {
 
   <div class="tab-bar">
     <button class="tab-btn active" data-tab="overview" type="button">Overview</button>
-    <button class="tab-btn" data-tab="control" type="button">Control</button>
-    <button class="tab-btn" data-tab="diagnostics" type="button">Diagnostics</button>
-    <button class="tab-btn" data-tab="activity" type="button">Activity</button>
+    <button class="tab-btn" data-tab="control" type="button">Transmission Control</button>
+    <button class="tab-btn" data-tab="diagnostics" type="button">Diagnostics &amp; Health</button>
+    <button class="tab-btn" data-tab="activity" type="button">Activity &amp; Logs</button>
   </div>
 
   <div class="tab-panels">
@@ -1099,16 +1095,24 @@ input.input-error {
         <div class="stack">
           <div class="card sidebar-card">
         <div class="sidebar-section">
-          <div class="sidebar-title">System Snapshot</div>
+          <div class="sidebar-title">Runtime Snapshot</div>
           <div class="kv">
             <div class="k">Backend</div><div class="v" id="info-backend">--</div>
             <div class="k">Frequency</div><div class="v" id="info-freq">--</div>
-            <div class="k">Pre-emphasis</div><div class="v" id="info-preemph">--</div>
-            <div class="k">FM Mod</div><div class="v" id="info-fmmod">--</div>
+            <div class="k">Runtime Age</div><div class="v" id="info-runtime-age">--</div>
+            <div class="k">Last Alert</div><div class="v" id="info-last-alert">--</div>
             <div class="k">Live Config</div><div class="v" id="info-live">--</div>
           </div>
         </div>
 
+        <div class="sidebar-section">
+          <div class="sidebar-title">Signal Notes</div>
+          <div class="section-note">Overview stays compact: primary state here, deep diagnostics in the dedicated tab.</div>
+          <div class="kv">
+            <div class="k">Pre-emphasis</div><div class="v" id="info-preemph">--</div>
+            <div class="k">FM Mod</div><div class="v" id="info-fmmod">--</div>
+          </div>
+        </div>
 
           </div>
         </div>
@@ -1249,7 +1253,7 @@ input.input-error {
           <span class="chevron">▼</span>
         </div>
         <div class="panel-body">
-          <div class="section-note">Fast control, as long as you're not typing in an input field.</div>
+          <div class="section-note">Fast control reference. Shortcuts stay out of the main operator path.</div>
           <div class="shortcuts-grid">
             <div>
               <div class="shortcut-line"><span class="name">Start TX</span><span class="keys"><span class="kbd">t</span></span></div>
@@ -2097,6 +2101,8 @@ function render() {
   updateText('info-freq', fmtFreq(cfg.fm?.frequencyMHz));
   updateText('info-preemph', cfg.fm?.preEmphasisTauUS ? `${cfg.fm.preEmphasisTauUS} µs` : 'Off');
   updateText('info-fmmod', fmtBool(cfg.fm?.fmModulationEnabled));
+  updateText('info-runtime-age', ageString(state.server.lastRuntimeAt));
+  updateText('info-last-alert', engine.runtimeAlert ? engine.runtimeAlert : (engine.lastError ? engine.lastError : 'None'));
   updateText('info-live', engine.state ? `${String(engine.state).toUpperCase()} / ${state.server.runtimeOk ? 'runtime ok' : 'runtime pending'}` : (state.server.configOk ? 'config only' : '--'));
 
   updateHealth(engine, driver, audioStream);
@@ -2486,6 +2492,16 @@ function log(message, type = '') {
   logEl.scrollTop = logEl.scrollHeight;
 }
 
+function bindTabs() {
+  const buttons = Array.from(document.querySelectorAll('.tab-btn[data-tab]'));
+  const panels = Array.from(document.querySelectorAll('.tab-panel[data-tab-panel]'));
+  const activate = (tab) => {
+    buttons.forEach((btn) => btn.classList.toggle('active', btn.dataset.tab === tab));
+    panels.forEach((panel) => panel.classList.toggle('active', panel.dataset.tabPanel === tab));
+  };
+  buttons.forEach((btn) => btn.addEventListener('click', () => activate(btn.dataset.tab)));
+}
+
 function bindPanels() {
   document.querySelectorAll('[data-panel]').forEach((head) => {
     head.addEventListener('click', () => {
@@ -2645,6 +2661,7 @@ function bindKeyboardShortcuts() {
 }
 
 async function init() {
+  bindTabs();
   bindPanels();
   bindInputs();
   bindResponsiveBehavior();