diff --git a/docs/src/SUMMARY.md b/docs/src/SUMMARY.md
index 1a4381c..2766509 100644
--- a/docs/src/SUMMARY.md
+++ b/docs/src/SUMMARY.md
@@ -1,13 +1,28 @@
 # Summary
 
-- [Kaptan documentation](index.md)
+- [Overview](index.md)
+
+# Start here
+
 - [Getting started](getting-started.md)
+- [Development and verification](development.md)
+
+# Design
+
 - [Architecture](architecture.md)
   - [Safety boundary](safety-boundary.md)
   - [MAVLink and telemetry](mavlink.md)
+
+# Platforms
+
 - [Boards](boards/index.md)
   - [Kakute F7 Mini V3](boards/kakute-f7-mini-v3.md)
   - [GEPRC GEP-F722-HD V2](boards/geprc-f722-v2.md)
+
+# Simulation
+
 - [Host SITL](sitl.md)
-- [Development and verification](development.md)
+
+# Reference
+
 - [Reference](reference.md)
diff --git a/docs/src/index.md b/docs/src/index.md
index 68397f3..ca152b6 100644
--- a/docs/src/index.md
+++ b/docs/src/index.md
@@ -1,13 +1,13 @@
-# Kaptan documentation
+# Overview
 
 Kaptan is an embedded Rust flight-controller project. This manual is the
 single source of project documentation: board support, safety boundaries,
 simulation, development workflow, and design references live here as
 Markdown.
 
-The checked-in firmware is telemetry-only. It does not expose physical motor
-authority, and no document in this site should be read as a physical-flight
-release claim.
+> **Status:** the checked-in firmware is telemetry-only. It does not expose
+> physical motor authority, and this site does not make a physical-flight
+> release claim.
 
 ## Index
 
diff --git a/docs/theme/lore.css b/docs/theme/lore.css
index 562c8e8..07a5dc6 100644
--- a/docs/theme/lore.css
+++ b/docs/theme/lore.css
@@ -9,27 +9,27 @@ html.coal,
 html.navy,
 html.ayu {
     --kaptan-background: #050505;
-    --kaptan-surface: #0a0a0a;
-    --kaptan-text: #cccccc;
-    --kaptan-muted: #888888;
+    --kaptan-surface: #101214;
+    --kaptan-text: #e5e7eb;
+    --kaptan-muted: #aab1b9;
     --kaptan-accent: #00ff41;
-    --kaptan-border: #333333;
+    --kaptan-border: #3a3d42;
 
     /* mdBook's generated content rules use these variables directly. */
     --bg: #050505;
     --fg: #e6e6e6;
-    --sidebar-bg: #0a0a0a;
+    --sidebar-bg: #101214;
     --sidebar-fg: #e6e6e6;
     --sidebar-non-existant: #888888;
     --sidebar-active: #00ff41;
-    --sidebar-spacer: #333333;
+    --sidebar-spacer: #3a3d42;
     --links: #00ff41;
     --inline-code-color: #e6e6e6;
-    --quote-bg: #0a0a0a;
-    --quote-border: #333333;
-    --table-border-color: #333333;
-    --table-header-bg: #0a0a0a;
-    --table-alternate-bg: #080808;
+    --quote-bg: #101214;
+    --quote-border: #3a3d42;
+    --table-border-color: #3a3d42;
+    --table-header-bg: #101214;
+    --table-alternate-bg: #0b0d0e;
     --color-scheme: dark;
 }
 
@@ -37,10 +37,10 @@ html,
 body {
     background: var(--kaptan-background);
     color: var(--fg);
-    font-family: "Roboto Mono", ui-monospace, SFMono-Regular, Menlo, Monaco,
-        Consolas, "Liberation Mono", monospace;
-    font-size: 16px;
-    line-height: 1.7;
+    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
+        sans-serif;
+    font-size: 17px;
+    line-height: 1.65;
 }
 
 * {
@@ -54,32 +54,10 @@ body {
 #mdbook-help-container,
 #mdbook-sidebar-toggle-anchor,
 #mdbook-menu-bar-hover-placeholder,
-#mdbook-menu-bar .left-buttons,
-#mdbook-menu-bar .right-buttons,
 #mdbook-sidebar-resize-handle {
     display: none !important;
 }
 
-#mdbook-menu-bar {
-    background: var(--kaptan-surface);
-    border-bottom: 1px solid var(--kaptan-border);
-    height: auto;
-    margin: 0;
-    min-height: 0;
-    padding: 0.65rem 1.25rem;
-    position: static;
-}
-
-#mdbook-menu-bar .menu-title {
-    color: var(--kaptan-text);
-    font-family: inherit;
-    font-size: 1rem;
-    font-weight: 700;
-    letter-spacing: 0.08em;
-    line-height: 1.35;
-    text-transform: uppercase;
-}
-
 #mdbook-sidebar {
     background: var(--kaptan-surface);
     border-right: 1px solid var(--kaptan-border);
@@ -102,21 +80,36 @@ body {
     margin: 0;
 }
 
+.sidebar-scrollbox .part-title {
+    color: var(--kaptan-muted);
+    font-size: 0.75rem;
+    font-weight: 700;
+    letter-spacing: 0.08em;
+    margin: 0;
+    padding: 1rem 1rem 0.3rem;
+    text-transform: uppercase;
+}
+
 .sidebar-scrollbox .chapter-item a {
     color: var(--kaptan-text);
     display: block;
-    font-size: 1rem;
+    font-size: 0.95rem;
     line-height: 1.5;
     padding: 0.4rem 1rem;
     text-decoration: none;
 }
 
-.sidebar-scrollbox .chapter-item a:hover,
-.sidebar-scrollbox .chapter-item a.active {
-    background: transparent;
+.sidebar-scrollbox .chapter-item a:hover {
     color: var(--kaptan-accent);
 }
 
+.sidebar-scrollbox .chapter-item a.active {
+    background: #122015;
+    border-left: 2px solid var(--kaptan-accent);
+    color: var(--kaptan-accent);
+    padding-left: calc(1rem - 2px);
+}
+
 .sidebar-scrollbox .section .chapter-item a {
     padding-left: 2rem;
 }
@@ -149,20 +142,20 @@ h4 {
 }
 
 h1 {
-    font-size: 1.35rem;
+    font-size: 1.8rem;
     margin: 0 0 1.25rem;
 }
 
 h2 {
     border-bottom: 1px solid var(--kaptan-border);
-    font-size: 1rem;
+    font-size: 1.3rem;
     margin: 2rem 0 0.75rem;
     padding-bottom: 0.35rem;
 }
 
 h3,
 h4 {
-    font-size: 1rem;
+    font-size: 1.08rem;
     margin: 1.5rem 0 0.5rem;
 }
 
@@ -198,7 +191,8 @@ li + li {
 code,
 pre,
 kbd {
-    font-family: inherit;
+    font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas,
+        "Liberation Mono", monospace;
 }
 
 code {
@@ -211,44 +205,27 @@ pre {
     background: var(--kaptan-surface);
     border: 1px solid var(--kaptan-border);
     overflow-x: auto;
-    padding: 0.75rem;
+    padding: 0;
 }
 
 pre code {
     padding: 0;
 }
 
-/* mdBook ships a separate highlight.js palette; keep it high contrast too. */
+/* Keep copied or highlighted commands monochrome and uniformly legible. */
 pre > code.hljs,
 .hljs {
-    background: #101010;
-    color: #f0f0f0;
+    background: transparent;
+    color: var(--kaptan-text);
 }
 
+.hljs *,
+.hljs-addition,
+.hljs-deletion,
 .hljs-comment,
 .hljs-quote {
-    color: #b8b8b8;
-}
-
-.hljs-keyword,
-.hljs-selector-tag,
-.hljs-literal,
-.hljs-type,
-.hljs-built_in,
-.hljs-builtin-name {
-    color: var(--kaptan-accent);
-}
-
-.hljs-string,
-.hljs-number,
-.hljs-meta,
-.hljs-params,
-.hljs-title,
-.hljs-section,
-.hljs-function,
-.hljs-variable,
-.hljs-attribute {
-    color: #e6e6e6;
+    background: transparent;
+    color: inherit;
 }
 
 table {
@@ -280,6 +257,10 @@ blockquote {
 }
 
 @media (min-width: 900px) {
+    #mdbook-menu-bar {
+        display: none !important;
+    }
+
     #mdbook-sidebar {
         bottom: 0;
         display: block !important;
@@ -298,6 +279,40 @@ blockquote {
 }
 
 @media (max-width: 899px) {
+    #mdbook-menu-bar {
+        background: var(--kaptan-surface);
+        border-bottom: 1px solid var(--kaptan-border);
+        display: block;
+        height: auto;
+        min-height: 0;
+        padding: 0.45rem 0.75rem;
+        position: static;
+    }
+
+    #mdbook-menu-bar .left-buttons {
+        display: block;
+    }
+
+    #mdbook-menu-bar .menu-title,
+    #mdbook-menu-bar .right-buttons {
+        display: none;
+    }
+
+    #mdbook-sidebar {
+        bottom: 0;
+        display: block !important;
+        left: 0;
+        position: fixed;
+        top: 0;
+        transform: translateX(-100%) !important;
+        width: min(17.5rem, 85vw);
+        z-index: 10;
+    }
+
+    #mdbook-sidebar-toggle-anchor:checked ~ #mdbook-sidebar {
+        transform: translateX(0) !important;
+    }
+
     #mdbook-page-wrapper,
     .page-wrapper {
         margin-left: 0 !important;