diff --git a/frontend/src/sidebar/Sidebar.jsx b/frontend/src/sidebar/Sidebar.jsx
index 4096a75..3df2376 100644
--- a/frontend/src/sidebar/Sidebar.jsx
+++ b/frontend/src/sidebar/Sidebar.jsx
@@ -83,7 +83,7 @@ const FolderNode = ({
           <div className="folder-row__actions">
             <button
               type="button"
-              className="icon-button"
+              className="icon-button ghost"
               onClick={(event) => {
                 event.stopPropagation();
                 if (!onRename) return;
@@ -104,7 +104,7 @@ const FolderNode = ({
             </button>
             <button
               type="button"
-              className="icon-button"
+              className="icon-button ghost"
               onClick={(event) => {
                 event.stopPropagation();
                 onDelete(node.id);
diff --git a/frontend/src/styles.css b/frontend/src/styles.css
index 6bb084f..4bff9a8 100644
--- a/frontend/src/styles.css
+++ b/frontend/src/styles.css
@@ -1,21 +1,24 @@
 :root {
-  color-scheme: light;
+  color-scheme: light dark;
 
-  /* master warmth bias: positive = warmer, negative = cooler */
-  --warmth: 3deg; /* try +5deg for warmer, -5deg for cooler */
+  --neutral-hue: 200deg;
+  --foreground-hue-offset: 70deg;
+  --accent-hue-offset: -20deg;
+  --dark-hue-offset: 60deg;
+  --dark-foreground-hue-offset: 70deg;
 
   /* --- Neutrals --- */
-  --bg: oklch(0.97 0.001 calc(100deg + var(--warmth)));
-  --surface: oklch(0.985 0.001 calc(100deg + var(--warmth)));
-  --surface-subtle: oklch(0.96 0.002 calc(100deg + var(--warmth)));
-  --fg: oklch(0.32 0.005 calc(270deg + var(--warmth)));
-  --muted: oklch(0.54 0.008 calc(270deg + var(--warmth)));
-  --sidebar-fg: oklch(0.56 0.007 calc(270deg + var(--warmth)));
-  --border: oklch(0.92 0.002 calc(270deg + var(--warmth)));
+  --bg: oklch(0.97 0.001 var(--neutral-hue));
+  --surface: oklch(0.985 0.001 var(--neutral-hue));
+  --surface-subtle: oklch(0.96 0.002 var(--neutral-hue));
+  --fg: oklch(0.32 0.005 calc(var(--neutral-hue) + var(--foreground-hue-offset)));
+  --muted: oklch(0.54 0.008 calc(var(--neutral-hue) + var(--foreground-hue-offset)));
+  --sidebar-fg: oklch(0.56 0.007 calc(var(--neutral-hue) + var(--foreground-hue-offset)));
+  --border: oklch(0.92 0.002 calc(var(--neutral-hue) + var(--foreground-hue-offset)));
 
   /* --- Accent (primary) --- */
-  --accent: oklch(0.61 0.2 calc(250deg + var(--warmth)));
-  --accent-hover: oklch(0.70 0.02 calc(100deg + var(--warmth)));
+  --accent: oklch(0.61 0.2 calc(var(--neutral-hue) + var(--foreground-hue-offset) + var(--accent-hue-offset)));
+  --accent-hover: oklch(0.70 0.02 calc(var(--neutral-hue) + var(--foreground-hue-offset) + var(--accent-hue-offset)));
   --on-accent: oklch(1 0 0);
 
   --accent-soft: color-mix(in oklch, var(--accent) 12%, transparent);
@@ -27,7 +30,7 @@
   --surface-overlay: color-mix(in oklch, white 82%, transparent);
 
   /* -- Selection --- */
-  --selection: oklch(0.61 0.01 calc(100deg + var(--warmth)));
+  --selection: oklch(0.61 0.01 var(--neutral-hue));
 
   /* --- Derived accent states --- */
   --selection-soft: color-mix(in oklch, var(--selection) 12%, transparent);
@@ -41,20 +44,20 @@
   --shadow-pop: color-mix(in oklch, black 25%, transparent);
   --outline-subtle: color-mix(in oklch, black 6%, transparent);
   --overlay-dark: color-mix(in oklch, black 55%, transparent);
-  --overlay-dim: color-mix(in oklch, oklch(0.28 0.01 calc(265deg + var(--warmth))) 20%, transparent);
+  --overlay-dim: color-mix(in oklch, oklch(0.28 0.01 calc(var(--neutral-hue) + var(--foreground-hue-offset) - 5deg)) 20%, transparent);
   --overlay-darker: color-mix(in oklch, black 75%, transparent);
   --surface-danger-subtle: color-mix(in oklch, var(--danger) 12%, transparent);
   --overlay-accent-subtle: color-mix(in oklch, var(--accent) 12%, transparent);
   --border-strong: color-mix(in oklch, var(--fg) 24%, transparent);
   --surface-hover: color-mix(in oklch, white 10%, transparent);
   --overlay-accent-strong: color-mix(in oklch, var(--accent) 24%, transparent);
-  --overlay-backdrop: color-mix(in oklch, oklch(0.22 0.015 calc(265deg + var(--warmth))) 45%, transparent);
-  --overlay-shadow: color-mix(in oklch, oklch(0.22 0.015 calc(265deg + var(--warmth))) 18%, transparent);
+  --overlay-backdrop: color-mix(in oklch, oklch(0.22 0.015 calc(var(--neutral-hue) + var(--foreground-hue-offset) - 5deg)) 45%, transparent);
+  --overlay-shadow: color-mix(in oklch, oklch(0.22 0.015 calc(var(--neutral-hue) + var(--foreground-hue-offset) - 5deg)) 18%, transparent);
 
-  /* --- Semantic colors (relative warmth) --- */
-  --success: oklch(0.62 0.18 calc(190deg + var(--warmth)));
-  --warning: oklch(0.72 0.17 calc(95deg + var(--warmth)));
-  --danger: oklch(0.60 0.18 calc(35deg + var(--warmth)));
+  /* --- Semantic colors --- */
+  --success: oklch(0.62 0.18 calc(var(--neutral-hue) + 90deg));
+  --warning: oklch(0.72 0.17 calc(var(--neutral-hue) - 5deg));
+  --danger: oklch(0.60 0.18 calc(var(--neutral-hue) - 65deg));
 
   --success-subtle: color-mix(in oklch, var(--success) 12%, transparent);
   --warning-subtle: color-mix(in oklch, var(--warning) 12%, transparent);
@@ -67,12 +70,12 @@
   --row-active-bg: color-mix(in oklch, var(--selection) 12%, transparent);
   --sidebar-hover-bg: color-mix(in oklch, var(--selection) 8%, transparent);
   --sidebar-active-bg: color-mix(in oklch, var(--selection) 16%, transparent);
-  --selection-ring: oklch(0.78 0.16 calc(260deg + var(--warmth)));
+  --selection-ring: oklch(0.78 0.16 calc(var(--neutral-hue) + var(--foreground-hue-offset)));
   --sidebar-active-pill-border: color-mix(in oklch, var(--accent) 64%, transparent);
   --link: var(--accent);
   --link-visited: color-mix(in oklch, var(--accent) 75%, var(--fg) 25%);
-  --preview-nav-bg: oklch(0.18 0.05 calc(270deg + var(--warmth)));
-  --preview-nav-bg-hover: oklch(0.14 0.05 calc(270deg + var(--warmth)));
+  --preview-nav-bg: oklch(0.18 0.05 calc(var(--neutral-hue) + var(--foreground-hue-offset)));
+  --preview-nav-bg-hover: oklch(0.14 0.05 calc(var(--neutral-hue) + var(--foreground-hue-offset)));
   --preview-nav-fg: var(--on-accent);
   --text-on-dark: color-mix(in oklch, white 90%, transparent);
   --surface-ink-soft: color-mix(in oklch, var(--fg) 8%, transparent);
@@ -85,6 +88,80 @@
   --documents-grid-title-size: 0.8rem;
 }
 
+@media (prefers-color-scheme: dark) {
+  :root {
+    color-scheme: dark;
+
+    --dark-neutral-hue: calc(var(--neutral-hue) + var(--dark-hue-offset));
+    --dark-foreground-hue: calc(var(--neutral-hue) + var(--dark-foreground-hue-offset));
+
+    --bg: oklch(0.15 0.01 var(--dark-neutral-hue));
+    --surface: oklch(0.19 0.012 var(--dark-neutral-hue));
+    --surface-subtle: oklch(0.23 0.012 var(--dark-neutral-hue));
+    --fg: oklch(0.89 0.015 var(--dark-foreground-hue));
+    --muted: oklch(0.72 0.02 var(--dark-foreground-hue));
+    --sidebar-fg: oklch(0.78 0.02 var(--dark-foreground-hue));
+    --border: oklch(0.33 0.01 var(--dark-foreground-hue));
+
+    --accent: oklch(0.75 0.2 calc(var(--dark-foreground-hue) + var(--accent-hue-offset)));
+    --accent-hover: oklch(0.82 0.16 calc(var(--dark-foreground-hue) + var(--accent-hue-offset)));
+    --on-accent: oklch(0.15 0.015 var(--dark-foreground-hue));
+
+    --accent-soft: color-mix(in oklch, var(--accent) 22%, transparent);
+    --accent-elevated: color-mix(in oklch, var(--accent) 28%, transparent);
+    --accent-elevated-strong: color-mix(in oklch, var(--accent) 38%, transparent);
+    --accent-outline: color-mix(in oklch, var(--accent) 55%, transparent);
+    --accent-outline-strong: color-mix(in oklch, var(--accent) 90%, transparent);
+    --accent-focus: color-mix(in oklch, var(--accent) 80%, transparent);
+    --surface-overlay: color-mix(in oklch, black 60%, transparent);
+
+    --selection: oklch(0.44 0.04 220deg);
+    --selection-soft: color-mix(in oklch, var(--selection) 18%, transparent);
+
+    --shadow-faint: color-mix(in oklch, black 35%, transparent);
+    --shadow-soft: color-mix(in oklch, black 50%, transparent);
+    --shadow-medium: color-mix(in oklch, black 65%, transparent);
+    --shadow-strong: color-mix(in oklch, black 80%, transparent);
+    --shadow-deep: color-mix(in oklch, black 90%, transparent);
+    --shadow-pop: color-mix(in oklch, black 70%, transparent);
+    --outline-subtle: color-mix(in oklch, white 10%, transparent);
+    --overlay-dark: color-mix(in oklch, black 70%, transparent);
+    --overlay-dim: color-mix(in oklch, oklch(0.42 0.04 var(--dark-neutral-hue)) 35%, transparent);
+    --overlay-darker: color-mix(in oklch, black 85%, transparent);
+    --surface-danger-subtle: color-mix(in oklch, var(--danger) 26%, transparent);
+    --overlay-accent-subtle: color-mix(in oklch, var(--accent) 32%, transparent);
+    --border-strong: color-mix(in oklch, var(--fg) 30%, transparent);
+    --surface-hover: color-mix(in oklch, white 6%, transparent);
+    --overlay-accent-strong: color-mix(in oklch, var(--accent) 55%, transparent);
+    --overlay-backdrop: color-mix(in oklch, oklch(0.1 0.015 var(--dark-neutral-hue)) 70%, transparent);
+    --overlay-shadow: color-mix(in oklch, oklch(0.12 0.015 var(--dark-neutral-hue)) 55%, transparent);
+
+    --success: oklch(0.72 0.16 180deg);
+    --warning: oklch(0.79 0.16 80deg);
+    --danger: oklch(0.7 0.16 25deg);
+
+    --success-subtle: color-mix(in oklch, var(--success) 20%, transparent);
+    --warning-subtle: color-mix(in oklch, var(--warning) 20%, transparent);
+    --danger-border: color-mix(in oklch, var(--danger) 45%, transparent);
+    --danger-soft: color-mix(in oklch, var(--danger) 24%, transparent);
+    --danger-subtle: color-mix(in oklch, var(--danger) 18%, transparent);
+
+    --row-hover-bg: color-mix(in oklch, white 4%, transparent);
+    --row-active-bg: color-mix(in oklch, var(--selection) 20%, transparent);
+    --sidebar-hover-bg: color-mix(in oklch, white 6%, transparent);
+    --sidebar-active-bg: color-mix(in oklch, var(--selection) 26%, transparent);
+    --selection-ring: oklch(0.68 0.16 var(--dark-foreground-hue));
+    --sidebar-active-pill-border: color-mix(in oklch, var(--accent) 72%, transparent);
+    --link: color-mix(in oklch, var(--accent) 92%, transparent);
+    --link-visited: color-mix(in oklch, var(--accent) 70%, white 20%);
+    --preview-nav-bg: oklch(0.3 0.04 var(--dark-neutral-hue));
+    --preview-nav-bg-hover: oklch(0.35 0.04 var(--dark-neutral-hue));
+    --preview-nav-fg: var(--fg);
+    --text-on-dark: color-mix(in oklch, white 92%, transparent);
+    --surface-ink-soft: color-mix(in oklch, white 12%, transparent);
+  }
+}
+
 html,
 body {
   height: 100%;