feat(ui): add responsive mobile menu with animated hamburger icon

- Add hamburger icon that morphs to X when menu is open
- Full-screen mobile menu overlay with backdrop blur
- Staggered fade-in animation for menu items
- Desktop navigation unchanged (hidden on mobile)
- Close menu via X button, backdrop click, or ESC key

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

assets/css/main.css

@@ -161,6 +161,46 @@ html {
     transform-origin: left;
   }
 
+  /* Hamburger Menu Icon */
+  .hamburger {
+    width: 20px;
+    height: 14px;
+    position: relative;
+    cursor: pointer;
+  }
+  .hamburger span {
+    display: block;
+    position: absolute;
+    width: 100%;
+    height: 2px;
+    background: var(--color-text-primary);
+    border-radius: var(--radius-full);
+    transition: all var(--duration-normal) var(--ease-out);
+  }
+  .hamburger span:nth-child(1) {
+    top: 0;
+  }
+  .hamburger span:nth-child(2) {
+    top: 50%;
+    transform: translateY(-50%);
+  }
+  .hamburger span:nth-child(3) {
+    bottom: 0;
+  }
+  /* Active state - transforms to X */
+  .hamburger.is-active span:nth-child(1) {
+    top: 50%;
+    transform: translateY(-50%) rotate(45deg);
+  }
+  .hamburger.is-active span:nth-child(2) {
+    opacity: 0;
+    transform: translateX(10px);
+  }
+  .hamburger.is-active span:nth-child(3) {
+    bottom: 50%;
+    transform: translateY(50%) rotate(-45deg);
+  }
+
   /* Audio Player */
   .audio-player {
     background: var(--color-surface-1);

layouts/partials/header.html

@@ -1,46 +1,121 @@
-<header class="fixed top-0 left-0 right-0 z-sticky bg-surface-0/80 backdrop-blur-md border-b border-border">
+<div x-data="{ menuOpen: false }" @keydown.escape.window="menuOpen = false">
-  <nav class="container-wide flex items-center justify-between h-16">
+  <header class="fixed top-0 left-0 right-0 z-sticky bg-surface-0/80 backdrop-blur-md border-b border-border">
-    {{/* Logo */}}
+    <nav class="container-wide flex items-center justify-between h-16">
-    <div class="flex items-center gap-3 group">
+      {{/* Logo */}}
-      <canvas
+      <div class="flex items-center gap-3 group">
-        id="logo-canvas"
+        <canvas
-        hx-preserve="true"
+          id="logo-canvas"
-        class="w-8 h-8 cursor-pointer"
+          hx-preserve="true"
-        width="32"
+          class="w-8 h-8 cursor-pointer"
-        height="32"
+          width="32"
-        aria-hidden="true"
+          height="32"
-        @click="window.__pivoine?.visualizer?.nextVisualizer()"
+          aria-hidden="true"
-        title="Click to change visualizer"
+          @click="window.__pivoine?.visualizer?.nextVisualizer()"
-      ></canvas>
+          title="Click to change visualizer"
-      <a
+        ></canvas>
-        href="{{ "/" | relURL }}"
+        <a
-        class="text-lg font-medium tracking-tight group-hover:text-accent transition-colors"
+          href="{{ "/" | relURL }}"
-        aria-label="{{ .Site.Title }} - Home"
+          class="text-lg font-medium tracking-tight group-hover:text-accent transition-colors"
+          aria-label="{{ .Site.Title }} - Home"
+        >
+          VALKNAR'S
+        </a>
+      </div>
+
+      {{/* Desktop Navigation */}}
+      <ul
+        class="hidden md:flex items-center gap-8"
+        x-data="{ path: window.location.pathname }"
+        @htmx:after-settle.window="path = window.location.pathname"
       >
-        VALKNAR'S
+        {{- range .Site.Menus.main }}
-      </a>
+        <li>
+          <a
+            href="{{ .URL }}"
+            class="text-sm transition-colors"
+            :class="path.startsWith('{{ .URL }}') ? 'text-text-primary border-b border-text-primary' : 'text-text-secondary hover:text-text-primary link-hover'"
+          >
+            {{ .Name }}
+          </a>
+        </li>
+        {{- end }}
+      </ul>
+
+      {{/* Mobile Hamburger Button */}}
+      <button
+        class="md:hidden relative w-8 h-8 flex items-center justify-center"
+        @click="menuOpen = !menuOpen"
+        :aria-expanded="menuOpen"
+        aria-label="Toggle menu"
+      >
+        <div class="hamburger" :class="{ 'is-active': menuOpen }">
+          <span></span>
+          <span></span>
+          <span></span>
+        </div>
+      </button>
+    </nav>
+  </header>
+
+  {{/* Mobile Menu Overlay - Full Screen */}}
+  <div
+    class="md:hidden fixed inset-0 z-[300]"
+    x-show="menuOpen"
+    x-cloak
+    x-transition:enter="transition ease-out duration-300"
+    x-transition:enter-start="opacity-0"
+    x-transition:enter-end="opacity-100"
+    x-transition:leave="transition ease-in duration-200"
+    x-transition:leave-start="opacity-100"
+    x-transition:leave-end="opacity-0"
+    @click="menuOpen = false"
+  >
+    {{/* Backdrop */}}
+    <div class="absolute inset-0 bg-surface-0/98 backdrop-blur-xl"></div>
+
+    {{/* Close Button - Top right corner */}}
+    <div class="absolute top-0 right-0 h-16 container-wide flex items-center justify-end z-10">
+      <button
+        class="w-8 h-8 flex items-center justify-center"
+        @click.stop="menuOpen = false"
+        aria-label="Close menu"
+      >
+        <div class="hamburger is-active">
+          <span></span>
+          <span></span>
+          <span></span>
+        </div>
+      </button>
     </div>
 
-    {{/* Navigation */}}
+    {{/* Menu Content */}}
-    <ul
+    <nav
-      class="flex items-center gap-4 md:gap-8"
+      class="relative h-full flex flex-col items-center justify-center"
       x-data="{ path: window.location.pathname }"
       @htmx:after-settle.window="path = window.location.pathname"
+      @click.stop
     >
-      {{- range .Site.Menus.main }}
+      <ul class="flex flex-col items-center gap-8">
-      <li>
+        {{- range $i, $item := .Site.Menus.main }}
-        <a
+        <li
-          href="{{ .URL }}"
+          class="transform transition-all duration-300 ease-out"
-          class="text-sm transition-colors"
+          :class="menuOpen ? 'opacity-100 translate-y-0' : 'opacity-0 translate-y-4'"
-          :class="path.startsWith('{{ .URL }}') ? 'text-text-primary border-b border-text-primary' : 'text-text-secondary hover:text-text-primary link-hover'"
+          style="transition-delay: {{ mul $i 50 }}ms"
         >
-          {{ .Name }}
+          <a
-        </a>
+            href="{{ .URL }}"
-      </li>
+            class="text-2xl font-medium tracking-wide transition-colors"
-      {{- end }}
+            :class="path.startsWith('{{ .URL }}') ? 'text-text-primary' : 'text-text-secondary hover:text-text-primary'"
-    </ul>
+            @click="menuOpen = false"
-  </nav>
+          >
-</header>
+            {{ .Name }}
+          </a>
+        </li>
+        {{- end }}
+      </ul>
+    </nav>
+  </div>
+</div>
 
 {{/* Spacer for fixed header */}}
 <div class="h-16" aria-hidden="true"></div>

static/css/main.css

@@ -34,9 +34,12 @@
     --leading-relaxed: 1.625;
     --radius-sm: 0.25rem;
     --radius-lg: 0.5rem;
+    --ease-in: cubic-bezier(0.4, 0, 1, 1);
     --ease-out: cubic-bezier(0, 0, 0.2, 1);
     --animate-bounce: bounce 1s infinite;
     --blur-md: 12px;
+    --blur-lg: 16px;
+    --blur-xl: 24px;
     --default-transition-duration: 150ms;
     --default-transition-timing-function: cubic-bezier(0.4, 0, 0.2, 1);
     --default-font-family: var(--font-sans);
@@ -238,6 +241,9 @@
   .z-10 {
     z-index: 10;
   }
+  .z-\[300\] {
+    z-index: 300;
+  }
   .z-player {
     z-index: 400;
   }
@@ -403,6 +409,14 @@
   .flex-shrink-0 {
     flex-shrink: 0;
   }
+  .translate-y-0 {
+    --tw-translate-y: calc(var(--spacing) * 0);
+    translate: var(--tw-translate-x) var(--tw-translate-y);
+  }
+  .translate-y-4 {
+    --tw-translate-y: calc(var(--spacing) * 4);
+    translate: var(--tw-translate-x) var(--tw-translate-y);
+  }
   .scale-90 {
     --tw-scale-x: 90%;
     --tw-scale-y: 90%;
@@ -451,6 +465,9 @@
   .gap-6 {
     gap: calc(var(--spacing) * 6);
   }
+  .gap-8 {
+    gap: calc(var(--spacing) * 8);
+  }
   .truncate {
     overflow: hidden;
     text-overflow: ellipsis;
@@ -501,6 +518,12 @@
       background-color: color-mix(in oklab, var(--color-surface-0) 80%, transparent);
     }
   }
+  .bg-surface-0\/98 {
+    background-color: var(--color-surface-0);
+    @supports (color: color-mix(in lab, red, red)) {
+      background-color: color-mix(in oklab, var(--color-surface-0) 98%, transparent);
+    }
+  }
   .bg-surface-2 {
     background-color: var(--color-surface-2);
   }
@@ -649,6 +672,9 @@
   .opacity-10 {
     opacity: 10%;
   }
+  .opacity-100 {
+    opacity: 100%;
+  }
   .shadow {
     --tw-shadow: 0 1px 3px 0 var(--tw-shadow-color, rgb(0 0 0 / 0.1)), 0 1px 2px -1px var(--tw-shadow-color, rgb(0 0 0 / 0.1));
     box-shadow: var(--tw-inset-shadow), var(--tw-inset-ring-shadow), var(--tw-ring-offset-shadow), var(--tw-ring-shadow), var(--tw-shadow);
@@ -669,6 +695,11 @@
     -webkit-backdrop-filter: var(--tw-backdrop-blur,) var(--tw-backdrop-brightness,) var(--tw-backdrop-contrast,) var(--tw-backdrop-grayscale,) var(--tw-backdrop-hue-rotate,) var(--tw-backdrop-invert,) var(--tw-backdrop-opacity,) var(--tw-backdrop-saturate,) var(--tw-backdrop-sepia,);
     backdrop-filter: var(--tw-backdrop-blur,) var(--tw-backdrop-brightness,) var(--tw-backdrop-contrast,) var(--tw-backdrop-grayscale,) var(--tw-backdrop-hue-rotate,) var(--tw-backdrop-invert,) var(--tw-backdrop-opacity,) var(--tw-backdrop-saturate,) var(--tw-backdrop-sepia,);
   }
+  .backdrop-blur-xl {
+    --tw-backdrop-blur: blur(var(--blur-xl));
+    -webkit-backdrop-filter: var(--tw-backdrop-blur,) var(--tw-backdrop-brightness,) var(--tw-backdrop-contrast,) var(--tw-backdrop-grayscale,) var(--tw-backdrop-hue-rotate,) var(--tw-backdrop-invert,) var(--tw-backdrop-opacity,) var(--tw-backdrop-saturate,) var(--tw-backdrop-sepia,);
+    backdrop-filter: var(--tw-backdrop-blur,) var(--tw-backdrop-brightness,) var(--tw-backdrop-contrast,) var(--tw-backdrop-grayscale,) var(--tw-backdrop-hue-rotate,) var(--tw-backdrop-invert,) var(--tw-backdrop-opacity,) var(--tw-backdrop-saturate,) var(--tw-backdrop-sepia,);
+  }
   .transition {
     transition-property: color, background-color, border-color, outline-color, text-decoration-color, fill, stroke, --tw-gradient-from, --tw-gradient-via, --tw-gradient-to, opacity, box-shadow, transform, translate, scale, rotate, filter, -webkit-backdrop-filter, backdrop-filter, display, content-visibility, overlay, pointer-events;
     transition-timing-function: var(--tw-ease, var(--default-transition-timing-function));
@@ -694,6 +725,14 @@
     transition-timing-function: var(--tw-ease, var(--default-transition-timing-function));
     transition-duration: var(--tw-duration, var(--default-transition-duration));
   }
+  .duration-150 {
+    --tw-duration: 150ms;
+    transition-duration: 150ms;
+  }
+  .duration-200 {
+    --tw-duration: 200ms;
+    transition-duration: 200ms;
+  }
   .duration-300 {
     --tw-duration: 300ms;
     transition-duration: 300ms;
@@ -702,6 +741,14 @@
     --tw-duration: 500ms;
     transition-duration: 500ms;
   }
+  .ease-in {
+    --tw-ease: var(--ease-in);
+    transition-timing-function: var(--ease-in);
+  }
+  .ease-out {
+    --tw-ease: var(--ease-out);
+    transition-timing-function: var(--ease-out);
+  }
   .group-hover\:translate-x-1 {
     &:is(:where(.group):hover *) {
       @media (hover: hover) {
@@ -900,6 +947,11 @@
       display: flex;
     }
   }
+  .md\:hidden {
+    @media (width >= 48rem) {
+      display: none;
+    }
+  }
   .md\:grid-cols-2 {
     @media (width >= 48rem) {
       grid-template-columns: repeat(2, minmax(0, 1fr));
@@ -915,11 +967,6 @@
       flex-direction: row;
     }
   }
-  .md\:gap-8 {
-    @media (width >= 48rem) {
-      gap: calc(var(--spacing) * 8);
-    }
-  }
   .md\:text-4xl {
     @media (width >= 48rem) {
       font-size: var(--text-4xl);
@@ -1057,6 +1104,43 @@ html {
     transform: scaleX(1);
     transform-origin: left;
   }
+  .hamburger {
+    width: 20px;
+    height: 14px;
+    position: relative;
+    cursor: pointer;
+  }
+  .hamburger span {
+    display: block;
+    position: absolute;
+    width: 100%;
+    height: 2px;
+    background: var(--color-text-primary);
+    border-radius: var(--radius-full);
+    transition: all var(--duration-normal) var(--ease-out);
+  }
+  .hamburger span:nth-child(1) {
+    top: 0;
+  }
+  .hamburger span:nth-child(2) {
+    top: 50%;
+    transform: translateY(-50%);
+  }
+  .hamburger span:nth-child(3) {
+    bottom: 0;
+  }
+  .hamburger.is-active span:nth-child(1) {
+    top: 50%;
+    transform: translateY(-50%) rotate(45deg);
+  }
+  .hamburger.is-active span:nth-child(2) {
+    opacity: 0;
+    transform: translateX(10px);
+  }
+  .hamburger.is-active span:nth-child(3) {
+    bottom: 50%;
+    transform: translateY(50%) rotate(-45deg);
+  }
   .audio-player {
     background: var(--color-surface-1);
     border-top: 1px solid var(--color-border);
@@ -1186,6 +1270,21 @@ html {
     transition-duration: 0.01ms !important;
   }
 }
+@property --tw-translate-x {
+  syntax: "*";
+  inherits: false;
+  initial-value: 0;
+}
+@property --tw-translate-y {
+  syntax: "*";
+  inherits: false;
+  initial-value: 0;
+}
+@property --tw-translate-z {
+  syntax: "*";
+  inherits: false;
+  initial-value: 0;
+}
 @property --tw-scale-x {
   syntax: "*";
   inherits: false;
@@ -1458,20 +1557,9 @@ html {
   syntax: "*";
   inherits: false;
 }
-@property --tw-translate-x {
+@property --tw-ease {
   syntax: "*";
   inherits: false;
-  initial-value: 0;
-}
-@property --tw-translate-y {
-  syntax: "*";
-  inherits: false;
-  initial-value: 0;
-}
-@property --tw-translate-z {
-  syntax: "*";
-  inherits: false;
-  initial-value: 0;
 }
 @property --tw-content {
   syntax: "*";
@@ -1491,6 +1579,9 @@ html {
 @layer properties {
   @supports ((-webkit-hyphens: none) and (not (margin-trim: inline))) or ((-moz-orient: inline) and (not (color:rgb(from red r g b)))) {
     *, ::before, ::after, ::backdrop {
+      --tw-translate-x: 0;
+      --tw-translate-y: 0;
+      --tw-translate-z: 0;
       --tw-scale-x: 1;
       --tw-scale-y: 1;
       --tw-scale-z: 1;
@@ -1554,9 +1645,7 @@ html {
       --tw-backdrop-saturate: initial;
       --tw-backdrop-sepia: initial;
       --tw-duration: initial;
-      --tw-translate-x: 0;
+      --tw-ease: initial;
-      --tw-translate-y: 0;
-      --tw-translate-z: 0;
       --tw-content: "";
     }
   }