diff --git a/frontend/index.html b/frontend/index.html
index 287bd2c..9a89007 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -51,6 +51,18 @@
           <input id="netFilter" placeholder="Filter nets" aria-label="Filter nets" />
           <ul id="netList" class="list" aria-label="Nets list"></ul>
         </section>
+        <section class="legendSection" aria-label="Net color legend">
+          <div class="sectionHead">
+            <h2>Legend</h2>
+          </div>
+          <div class="netLegend">
+            <div class="legendRow"><span class="legendSwatch legendPower"></span>Power</div>
+            <div class="legendRow"><span class="legendSwatch legendGround"></span>Ground</div>
+            <div class="legendRow"><span class="legendSwatch legendClock"></span>Clock</div>
+            <div class="legendRow"><span class="legendSwatch legendSignal"></span>Signal</div>
+            <div class="legendRow"><span class="legendSwatch legendAnalog"></span>Analog</div>
+          </div>
+        </section>
       </aside>
 
       <section class="pane center">
diff --git a/frontend/styles.css b/frontend/styles.css
index 404a347..6f5a112 100644
--- a/frontend/styles.css
+++ b/frontend/styles.css
@@ -1,56 +1,50 @@
 :root {
-  --bg: #eef2f6;
-  --panel: #ffffff;
-  --ink: #1d2939;
-  --ink-soft: #667085;
-  --line: #d0d5dd;
-  --accent: #155eef;
-  --accent-soft: #dbe8ff;
-  --warn: #b54708;
-  --error: #b42318;
-  --ok: #067647;
+  --bg-0: #f5f7fb;
+  --bg-1: #ebf1f8;
+  --bg-2: #dce8f4;
+  --panel: #fbfdff;
+  --panel-strong: #ffffff;
+  --canvas: #f4f8fd;
+  --ink: #0f1728;
+  --ink-muted: #4a607c;
+  --ink-subtle: #7388a3;
+  --line: #c8d5e4;
+  --line-strong: #9db1c9;
+  --accent: #1565d8;
+  --accent-strong: #0f4dab;
+  --accent-soft: #e6f0ff;
+  --ok: #0f7a49;
+  --warn: #9b6200;
+  --err: #ac2f24;
+  --power: #d6691f;
+  --ground: #60748d;
+  --clock: #d35c2f;
+  --signal: #2f72e7;
+  --analog: #0d978e;
+  --radius-sm: 8px;
+  --radius-md: 12px;
+  --radius-lg: 16px;
+  --shadow-1: 0 1px 2px rgba(16, 24, 40, 0.08);
+  --shadow-2: 0 10px 24px rgba(16, 24, 40, 0.08);
 }
 
 * {
   box-sizing: border-box;
 }
 
+html,
 body {
   margin: 0;
-  font-family: "Manrope", "Segoe UI", sans-serif;
+  min-height: 100%;
+}
+
+body {
+  font-family: "IBM Plex Sans", "Manrope", "Segoe UI", sans-serif;
   color: var(--ink);
-  background: radial-gradient(circle at 8% 8%, #fef7e6, transparent 30%),
-    radial-gradient(circle at 88% 12%, #e0f2ff, transparent 30%), var(--bg);
-  min-height: 100vh;
-}
-
-.topbar {
-  display: flex;
-  justify-content: space-between;
-  align-items: center;
-  padding: 10px 12px;
-  border-bottom: 1px solid var(--line);
-  background: #f7fbffde;
-  backdrop-filter: blur(4px);
-}
-
-.brand h1 {
-  margin: 0;
-  font-size: 1.2rem;
-  letter-spacing: 0.08em;
-}
-
-.brand p {
-  margin: 2px 0 0;
-  color: var(--ink-soft);
-  font-size: 0.8rem;
-}
-
-.actions {
-  display: flex;
-  flex-wrap: wrap;
-  gap: 8px;
-  align-items: center;
+  background:
+    radial-gradient(circle at 0% 0%, #fff4de 0 20%, transparent 30%),
+    radial-gradient(circle at 96% 5%, #dbf2ff 0 18%, transparent 28%),
+    linear-gradient(180deg, var(--bg-1), var(--bg-0));
 }
 
 button,
@@ -60,44 +54,101 @@ textarea {
   font: inherit;
 }
 
-button {
-  border: 1px solid var(--line);
-  border-radius: 8px;
-  background: #fff;
-  padding: 6px 10px;
-  color: var(--ink);
-  cursor: pointer;
-}
-
-button:disabled {
-  opacity: 0.5;
-  cursor: not-allowed;
+button,
+input,
+select,
+textarea,
+.list li,
+details > summary {
+  transition: background-color 120ms ease, border-color 120ms ease, box-shadow 120ms ease, color 120ms ease;
 }
 
 button:focus-visible,
 input:focus-visible,
 select:focus-visible,
 textarea:focus-visible,
-.list li:focus-visible {
-  outline: 2px solid #155eef;
+.list li:focus-visible,
+details > summary:focus-visible {
+  outline: 2px solid var(--accent);
   outline-offset: 1px;
 }
 
+button {
+  border: 1px solid var(--line);
+  border-radius: var(--radius-sm);
+  background: var(--panel-strong);
+  color: var(--ink);
+  padding: 6px 11px;
+  cursor: pointer;
+  box-shadow: var(--shadow-1);
+}
+
+button:hover {
+  border-color: var(--line-strong);
+  background: #f3f8ff;
+}
+
+button:disabled {
+  opacity: 0.48;
+  cursor: not-allowed;
+}
+
 button.primary {
+  border-color: var(--accent);
   background: var(--accent);
   color: #fff;
-  border-color: var(--accent);
+}
+
+button.primary:hover {
+  background: var(--accent-strong);
+  border-color: var(--accent-strong);
 }
 
 button.chip {
-  padding: 4px 8px;
+  padding: 4px 9px;
   font-size: 0.76rem;
 }
 
 button.activeChip {
   background: var(--accent-soft);
   border-color: var(--accent);
-  color: #0f3ea3;
+  color: var(--accent-strong);
+}
+
+.topbar {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 14px;
+  padding: 10px 12px;
+  border-bottom: 1px solid var(--line);
+  background: linear-gradient(180deg, #f9fcff, #f2f8ff);
+  backdrop-filter: blur(2px);
+  position: sticky;
+  top: 0;
+  z-index: 40;
+}
+
+.brand h1 {
+  margin: 0;
+  font-size: 1.6rem;
+  letter-spacing: 0.08em;
+  line-height: 1;
+}
+
+.brand p {
+  margin: 2px 0 0;
+  font-size: 0.84rem;
+  color: var(--ink-muted);
+  font-weight: 600;
+}
+
+.actions {
+  display: flex;
+  flex-wrap: wrap;
+  justify-content: flex-end;
+  align-items: center;
+  gap: 7px;
 }
 
 .inlineSelect,
@@ -109,24 +160,22 @@ button.activeChip {
 }
 
 .inlineSelect select {
-  border: 1px solid var(--line);
-  border-radius: 8px;
-  padding: 5px 8px;
+  min-width: 138px;
 }
 
 .workspace {
-  height: calc(100vh - 65px);
+  height: calc(100vh - 77px);
   display: grid;
-  grid-template-columns: 270px minmax(480px, 1fr) 380px;
   gap: 10px;
+  grid-template-columns: 270px minmax(520px, 1fr) 392px;
   padding: 10px;
 }
 
 .pane {
-  background: var(--panel);
   border: 1px solid var(--line);
-  border-radius: 12px;
-  overflow: hidden;
+  border-radius: var(--radius-md);
+  background: linear-gradient(180deg, var(--panel), #f6faff);
+  box-shadow: var(--shadow-1);
 }
 
 .pane.left,
@@ -138,16 +187,27 @@ button.activeChip {
   overflow: auto;
 }
 
+.pane.center {
+  overflow: hidden;
+  background: linear-gradient(180deg, #fcfeff, #f6faff);
+}
+
 .sectionHead {
   display: flex;
-  justify-content: space-between;
   align-items: center;
+  justify-content: space-between;
   gap: 8px;
 }
 
 .sectionHead h2 {
   margin: 0;
-  font-size: 0.9rem;
+  font-size: 0.92rem;
+  color: var(--ink);
+}
+
+h2 {
+  margin: 0;
+  font-size: 0.94rem;
 }
 
 input,
@@ -155,32 +215,44 @@ textarea,
 select {
   width: 100%;
   border: 1px solid var(--line);
-  border-radius: 8px;
+  border-radius: var(--radius-sm);
   padding: 8px;
+  background: #fff;
   color: var(--ink);
 }
 
+input::placeholder,
+textarea::placeholder {
+  color: var(--ink-subtle);
+}
+
 textarea {
   min-height: 250px;
-  font-family: "JetBrains Mono", monospace;
+  font-family: "JetBrains Mono", "IBM Plex Mono", monospace;
   font-size: 12px;
-  line-height: 1.45;
+  line-height: 1.42;
 }
 
 .list {
   margin: 8px 0 0;
-  padding: 0;
   list-style: none;
-  max-height: 230px;
+  padding: 0;
+  max-height: 250px;
   overflow: auto;
   border: 1px solid var(--line);
-  border-radius: 8px;
+  border-radius: var(--radius-sm);
+  background: rgba(255, 255, 255, 0.72);
 }
 
 .list li {
   padding: 8px;
   border-bottom: 1px solid var(--line);
   cursor: pointer;
+  color: var(--ink);
+}
+
+.list li:hover {
+  background: #f2f7ff;
 }
 
 .list li:last-child {
@@ -189,6 +261,8 @@ textarea {
 
 .list li.active {
   background: var(--accent-soft);
+  color: #0b3a84;
+  font-weight: 600;
 }
 
 .list li.listSpacer {
@@ -198,11 +272,60 @@ textarea {
   background: transparent;
 }
 
+.legendSection {
+  margin-top: 2px;
+}
+
+.netLegend {
+  border: 1px solid var(--line);
+  border-radius: var(--radius-sm);
+  background: #fbfdff;
+  padding: 8px;
+  display: grid;
+  gap: 6px;
+}
+
+.legendRow {
+  display: inline-flex;
+  align-items: center;
+  gap: 8px;
+  font-size: 0.8rem;
+  color: var(--ink-muted);
+}
+
+.legendSwatch {
+  display: inline-block;
+  width: 20px;
+  height: 0;
+  border-top: 3px solid var(--line-strong);
+}
+
+.legendPower {
+  border-top-color: var(--power);
+}
+
+.legendGround {
+  border-top-color: var(--ground);
+}
+
+.legendClock {
+  border-top-color: var(--clock);
+}
+
+.legendSignal {
+  border-top-color: var(--signal);
+}
+
+.legendAnalog {
+  border-top-color: var(--analog);
+}
+
 .card {
   border: 1px solid var(--line);
-  border-radius: 8px;
+  border-radius: var(--radius-sm);
+  background: #fbfdff;
   padding: 8px;
-  color: var(--ink-soft);
+  color: var(--ink-muted);
   font-size: 0.85rem;
   white-space: pre-wrap;
 }
@@ -210,9 +333,9 @@ textarea {
 .editorCard {
   margin-top: 8px;
   border: 1px solid var(--line);
-  border-radius: 8px;
-  padding: 8px;
-  background: #fcfcfd;
+  border-radius: var(--radius-sm);
+  padding: 9px;
+  background: #f8fbff;
   display: flex;
   flex-direction: column;
   gap: 8px;
@@ -220,9 +343,10 @@ textarea {
 
 .editorSection {
   border: 1px solid var(--line);
-  border-radius: 8px;
+  border-radius: var(--radius-sm);
   margin-top: 8px;
-  background: #fff;
+  background: #ffffffcc;
+  overflow: hidden;
 }
 
 .editorSection > summary {
@@ -232,11 +356,15 @@ textarea {
   font-size: 0.8rem;
   font-weight: 700;
   color: var(--ink);
-  border-bottom: 1px solid transparent;
+}
+
+.editorSection > summary:hover {
+  background: #f3f8ff;
 }
 
 .editorSection[open] > summary {
-  border-bottom-color: var(--line);
+  border-bottom: 1px solid var(--line);
+  background: #eef4ff;
 }
 
 .editorSection > summary::-webkit-details-marker {
@@ -251,27 +379,27 @@ textarea {
 
 .editorActions {
   display: flex;
-  gap: 8px;
   flex-wrap: wrap;
+  gap: 8px;
 }
 
 .hintText {
   font-size: 0.8rem;
-  color: var(--ink-soft);
+  color: var(--ink-muted);
 }
 
 .miniList {
   border: 1px solid var(--line);
-  border-radius: 8px;
+  border-radius: var(--radius-sm);
   background: #fff;
-  max-height: 170px;
+  max-height: 180px;
   overflow: auto;
 }
 
 .miniRow {
   display: flex;
-  justify-content: space-between;
   align-items: center;
+  justify-content: space-between;
   gap: 8px;
   padding: 6px 8px;
   border-bottom: 1px solid var(--line);
@@ -284,47 +412,48 @@ textarea {
 
 .symbolPinRow {
   display: grid;
-  grid-template-columns: 1fr 0.9fr 0.9fr 0.8fr 1fr auto auto auto;
   align-items: center;
+  grid-template-columns: 1fr 0.9fr 0.9fr 0.8fr 1fr auto auto auto;
 }
 
 .pinCol {
   min-width: 0;
   padding: 5px 6px;
-  font-size: 0.75rem;
+  font-size: 0.76rem;
 }
 
 .symbolPinRow.invalidRow {
-  background: #fff3f2;
+  background: #fff3f1;
 }
 
 .symbolValidationError {
-  color: var(--error);
+  color: var(--err);
   font-size: 0.76rem;
 }
 
 .migrationPreview {
   border: 1px solid var(--line);
-  border-radius: 8px;
+  border-radius: var(--radius-sm);
   padding: 8px;
-  background: #f8fafc;
-  margin-top: 6px;
-  margin-bottom: 6px;
+  margin: 6px 0;
   line-height: 1.35;
+  background: #f5f9ff;
 }
 
 .canvasTools {
   display: flex;
-  gap: 8px;
   align-items: center;
-  border-bottom: 1px solid var(--line);
+  gap: 8px;
   padding: 8px;
+  border-bottom: 1px solid var(--line);
+  background: linear-gradient(180deg, #f8fbff, #f2f7ff);
 }
 
 #compileStatus {
   margin-left: auto;
-  color: var(--ink-soft);
+  color: var(--ink-muted);
   font-size: 0.84rem;
+  font-weight: 600;
 }
 
 .status-ok {
@@ -333,12 +462,14 @@ textarea {
 
 .canvasViewport {
   height: calc(100% - 52px);
-  overflow: hidden;
   position: relative;
+  overflow: hidden;
   cursor: grab;
-  background-image: linear-gradient(0deg, #ebeff3 1px, transparent 1px),
-    linear-gradient(90deg, #ebeff3 1px, transparent 1px);
-  background-size: 20px 20px;
+  background:
+    linear-gradient(0deg, #d9e4f0 1px, transparent 1px),
+    linear-gradient(90deg, #d9e4f0 1px, transparent 1px),
+    linear-gradient(180deg, var(--canvas), #edf4fc);
+  background-size: 20px 20px, 20px 20px, auto;
 }
 
 .canvasViewport.dragging {
@@ -346,10 +477,10 @@ textarea {
 }
 
 .canvasInner {
-  transform-origin: 0 0;
   position: absolute;
-  left: 0;
   top: 0;
+  left: 0;
+  transform-origin: 0 0;
 }
 
 .canvasInner svg {
@@ -358,10 +489,23 @@ textarea {
 
 .selectionBox {
   position: absolute;
-  border: 1px solid #155eef;
-  background: rgba(21, 94, 239, 0.12);
-  pointer-events: none;
   z-index: 15;
+  pointer-events: none;
+  border: 1px solid var(--accent);
+  background: rgba(21, 101, 216, 0.12);
+}
+
+.pinTooltip {
+  position: absolute;
+  z-index: 20;
+  pointer-events: none;
+  border: 1px solid var(--line);
+  border-radius: var(--radius-sm);
+  padding: 6px 8px;
+  color: var(--ink);
+  background: rgba(255, 255, 255, 0.95);
+  box-shadow: var(--shadow-2);
+  font-size: 0.74rem;
 }
 
 .hidden {
@@ -375,20 +519,20 @@ textarea {
 }
 
 .jsonActions button {
+  font-size: 0.77rem;
   padding: 4px 8px;
-  font-size: 0.78rem;
 }
 
 .jsonFeedback {
   min-height: 18px;
-  color: var(--ink-soft);
-  font-size: 0.78rem;
   margin-bottom: 6px;
+  color: var(--ink-muted);
+  font-size: 0.78rem;
 }
 
 .issueRow {
   border: 1px solid var(--line);
-  border-radius: 7px;
+  border-radius: 8px;
   padding: 7px;
   margin-bottom: 6px;
   cursor: pointer;
@@ -396,51 +540,39 @@ textarea {
 }
 
 .issueRow:hover {
-  background: #f8faff;
+  background: #f4f8ff;
 }
 
 .issueErr {
-  border-color: #fecdca;
-  background: #fff6f5;
+  border-color: #f3bab5;
+  background: #fff5f4;
 }
 
 .issueWarn {
-  border-color: #fedf89;
-  background: #fffcf5;
+  border-color: #f0d28b;
+  background: #fffaf0;
 }
 
 .issueTitle {
   font-size: 0.8rem;
   font-weight: 700;
+  color: var(--ink);
 }
 
 .issueMeta {
   font-size: 0.72rem;
-  color: var(--ink-soft);
-}
-
-.pinTooltip {
-  position: absolute;
-  pointer-events: none;
-  padding: 6px 8px;
-  border: 1px solid var(--line);
-  border-radius: 8px;
-  background: #ffffffee;
-  color: var(--ink);
-  font-size: 0.74rem;
-  z-index: 20;
-  box-shadow: 0 6px 20px rgba(16, 24, 40, 0.12);
+  color: var(--ink-muted);
 }
 
 .modal {
   position: fixed;
   inset: 0;
-  background: rgba(15, 23, 42, 0.45);
   z-index: 70;
   display: flex;
   align-items: center;
   justify-content: center;
   padding: 18px;
+  background: rgba(14, 22, 36, 0.54);
 }
 
 .modal.hidden {
@@ -450,9 +582,10 @@ textarea {
 .modalCard {
   width: min(1120px, 100%);
   height: min(88vh, 900px);
-  background: #fff;
   border: 1px solid var(--line);
-  border-radius: 12px;
+  border-radius: var(--radius-lg);
+  background: #fff;
+  box-shadow: 0 24px 60px rgba(16, 24, 40, 0.24);
   padding: 12px;
   display: flex;
   flex-direction: column;
@@ -461,19 +594,19 @@ textarea {
 
 .modalHead {
   display: flex;
-  justify-content: space-between;
   align-items: center;
+  justify-content: space-between;
   gap: 10px;
 }
 
 .modalHead h3 {
   margin: 0;
-  font-size: 0.95rem;
+  font-size: 0.96rem;
 }
 
 .modalHint {
   margin: 0;
-  color: var(--ink-soft);
+  color: var(--ink-muted);
   font-size: 0.8rem;
 }
 
@@ -495,14 +628,38 @@ textarea {
   }
 }
 
+@media (max-width: 1460px) {
+  .workspace {
+    grid-template-columns: 248px minmax(420px, 1fr) 360px;
+  }
+}
+
 @media (max-width: 1300px) {
   .workspace {
+    height: auto;
     grid-template-columns: 1fr;
     grid-template-rows: auto auto auto;
-    height: auto;
   }
 
   .pane.center {
-    min-height: 560px;
+    min-height: 600px;
+  }
+}
+
+@media (max-width: 820px) {
+  .topbar {
+    position: static;
+  }
+
+  .brand h1 {
+    font-size: 1.3rem;
+  }
+
+  .actions {
+    justify-content: flex-start;
+  }
+
+  .editorGrid {
+    grid-template-columns: 1fr;
   }
 }
diff --git a/tests/baselines/ui/dense-analog.png b/tests/baselines/ui/dense-analog.png
index fba3fa8..bef7b68 100644
Binary files a/tests/baselines/ui/dense-analog.png and b/tests/baselines/ui/dense-analog.png differ
diff --git a/tests/baselines/ui/explicit-mode-auto-tidy.png b/tests/baselines/ui/explicit-mode-auto-tidy.png
index 35e1d5c..d906f37 100644
Binary files a/tests/baselines/ui/explicit-mode-auto-tidy.png and b/tests/baselines/ui/explicit-mode-auto-tidy.png differ
diff --git a/tests/baselines/ui/initial.png b/tests/baselines/ui/initial.png
index 028d1ec..bddb8e8 100644
Binary files a/tests/baselines/ui/initial.png and b/tests/baselines/ui/initial.png differ
diff --git a/tests/baselines/ui/post-migration-apply.png b/tests/baselines/ui/post-migration-apply.png
index 93f1f9a..b1afd6c 100644
Binary files a/tests/baselines/ui/post-migration-apply.png and b/tests/baselines/ui/post-migration-apply.png differ
diff --git a/tests/baselines/ui/selected-u2.png b/tests/baselines/ui/selected-u2.png
index 15344a0..947ef0b 100644
Binary files a/tests/baselines/ui/selected-u2.png and b/tests/baselines/ui/selected-u2.png differ