data/frontend/src/styles/tailwind.css

/* src/styles/tailwind.css */
@import "tailwindcss";
@import "tw-animate-css";

@plugin "@tailwindcss/typography";

@custom-variant dark (&:where(.dark, .dark *));

/* ===== shadcn/ui CSS Variables (OKLCH) ===== */
:root {
  --radius: 0.625rem;
  /* Light mode: sky/slate palette */
  --background: oklch(0.9688 0.0035 264.54); /* slate-100 */
  --foreground: oklch(0.2078 0.0397 265.75); /* slate-900 */
  --card: oklch(1 0 0); /* white */
  --card-foreground: oklch(0.2078 0.0397 265.75); /* slate-900 */
  --popover: oklch(1 0 0); /* white */
  --popover-foreground: oklch(0.2078 0.0397 265.75); /* slate-900 */
  --primary: oklch(0.5459 0.1522 241.22); /* sky-600 */
  --primary-foreground: oklch(1 0 0); /* white */
  --secondary: oklch(0.9282 0.0069 264.53); /* slate-200 */
  --secondary-foreground: oklch(0.2078 0.0397 265.75); /* slate-900 */
  --muted: oklch(0.9282 0.0069 264.53); /* slate-200 */
  --muted-foreground: oklch(0.5542 0.0255 264.36); /* slate-500 */
  --accent: oklch(0.9282 0.0069 264.53); /* slate-200 */
  --accent-foreground: oklch(0.2078 0.0397 265.75); /* slate-900 */
  --destructive: oklch(0.5774 0.2157 27.33); /* red-600 */
  --border: oklch(0.8694 0.0106 264.53); /* slate-300 */
  --input: oklch(0.8694 0.0106 264.53); /* slate-300 */
  --ring: oklch(0.5459 0.1522 241.22); /* sky-600 */
  --chart-1: oklch(0.6469 0.1651 231.11); /* sky-500 */
  --chart-2: oklch(0.5826 0.1556 254.62); /* indigo-500 */
  --chart-3: oklch(0.6275 0.1454 292.79); /* purple-500 */
  --chart-4: oklch(0.6382 0.1773 25.72); /* orange-500 */
  --chart-5: oklch(0.723 0.1907 149.58); /* green-500 */
  --sidebar-background: oklch(0.9688 0.0035 264.54); /* slate-100 */
  --sidebar-foreground: oklch(0.2078 0.0397 265.75); /* slate-900 */
  --sidebar-primary: oklch(0.5459 0.1522 241.22); /* sky-600 */
  --sidebar-primary-foreground: oklch(1 0 0); /* white */
  --sidebar-accent: oklch(0.9282 0.0069 264.53); /* slate-200 */
  --sidebar-accent-foreground: oklch(0.2078 0.0397 265.75); /* slate-900 */
  --sidebar-border: oklch(0.8694 0.0106 264.53); /* slate-300 */
  --sidebar-ring: oklch(0.5459 0.1522 241.22); /* sky-600 */
}

.dark {
  /* Dark mode: sky/slate palette with custom gray-950 background */
  --background: oklch(0.16 0.02 250); /* #0f1521 custom gray-950 */
  --foreground: oklch(0.9688 0.0035 264.54); /* slate-100 */
  --card: oklch(0.2955 0.0301 265.75); /* slate-800 */
  --card-foreground: oklch(0.9688 0.0035 264.54); /* slate-100 */
  --popover: oklch(0.2955 0.0301 265.75); /* slate-800 */
  --popover-foreground: oklch(0.9688 0.0035 264.54); /* slate-100 */
  --primary: oklch(0.7461 0.1248 241.02); /* sky-400 */
  --primary-foreground: oklch(0.16 0.02 250); /* gray-950 */
  --secondary: oklch(0.3937 0.0278 265.75); /* slate-700 */
  --secondary-foreground: oklch(0.9688 0.0035 264.54); /* slate-100 */
  --muted: oklch(0.3937 0.0278 265.75); /* slate-700 */
  --muted-foreground: oklch(0.7041 0.0177 264.53); /* slate-400 */
  --accent: oklch(0.3937 0.0278 265.75); /* slate-700 */
  --accent-foreground: oklch(0.9688 0.0035 264.54); /* slate-100 */
  --destructive: oklch(0.5774 0.2157 27.33); /* red-600 */
  --border: oklch(0.3937 0.0278 265.75); /* slate-700 */
  --input: oklch(0.3937 0.0278 265.75); /* slate-700 */
  --ring: oklch(0.7461 0.1248 241.02); /* sky-400 */
  --chart-1: oklch(0.7461 0.1248 241.02); /* sky-400 */
  --chart-2: oklch(0.7187 0.1686 254.62); /* indigo-400 */
  --chart-3: oklch(0.7141 0.1648 292.79); /* purple-400 */
  --chart-4: oklch(0.7483 0.183 55.93); /* amber-400 */
  --chart-5: oklch(0.7926 0.1947 149.58); /* green-400 */
  --sidebar-background: oklch(0.16 0.02 250); /* custom gray-950 */
  --sidebar-foreground: oklch(0.9688 0.0035 264.54); /* slate-100 */
  --sidebar-primary: oklch(0.7461 0.1248 241.02); /* sky-400 */
  --sidebar-primary-foreground: oklch(0.16 0.02 250); /* gray-950 */
  --sidebar-accent: oklch(0.3937 0.0278 265.75); /* slate-700 */
  --sidebar-accent-foreground: oklch(0.9688 0.0035 264.54); /* slate-100 */
  --sidebar-border: oklch(0.3937 0.0278 265.75); /* slate-700 */
  --sidebar-ring: oklch(0.7461 0.1248 241.02); /* sky-400 */
}

/* ===== Map CSS variables to Tailwind utilities via @theme ===== */
@theme inline {
  --color-background: var(--background);
  --color-foreground: var(--foreground);
  --color-card: var(--card);
  --color-card-foreground: var(--card-foreground);
  --color-popover: var(--popover);
  --color-popover-foreground: var(--popover-foreground);
  --color-primary: var(--primary);
  --color-primary-foreground: var(--primary-foreground);
  --color-secondary: var(--secondary);
  --color-secondary-foreground: var(--secondary-foreground);
  --color-muted: var(--muted);
  --color-muted-foreground: var(--muted-foreground);
  --color-accent: var(--accent);
  --color-accent-foreground: var(--accent-foreground);
  --color-destructive: var(--destructive);
  --color-border: var(--border);
  --color-input: var(--input);
  --color-ring: var(--ring);
  --color-chart-1: var(--chart-1);
  --color-chart-2: var(--chart-2);
  --color-chart-3: var(--chart-3);
  --color-chart-4: var(--chart-4);
  --color-chart-5: var(--chart-5);
  --color-sidebar-background: var(--sidebar-background);
  --color-sidebar-foreground: var(--sidebar-foreground);
  --color-sidebar-primary: var(--sidebar-primary);
  --color-sidebar-primary-foreground: var(--sidebar-primary-foreground);
  --color-sidebar-accent: var(--sidebar-accent);
  --color-sidebar-accent-foreground: var(--sidebar-accent-foreground);
  --color-sidebar-border: var(--sidebar-border);
  --color-sidebar-ring: var(--sidebar-ring);
  --radius-sm: calc(var(--radius) - 4px);
  --radius-md: calc(var(--radius) - 2px);
  --radius-lg: var(--radius);
  --radius-xl: calc(var(--radius) + 4px);
}

@theme {
  /* Custom color shades (non-default) */
  --color-gray-750: #2b3544;
  --color-gray-850: #1a2231;
  --color-gray-950: #0f1521; /* Keep: different from v4 default #030712 */

  --color-blue-350: #7dabf8;
  --color-blue-450: #4f85e6;
  --color-blue-550: #3a72d6;
  --color-blue-650: #2a5db8;
  --color-blue-750: #214a98;
  --color-blue-850: #183878;

  /* Font stacks */
  --font-sans:
    "Inter", ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  --font-mono:
    "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono",
    "Courier New", monospace;

  /* Custom animations (from old tailwind.config.js) */
  --animate-pulse-slow: pulse 3s cubic-bezier(0.4, 0, 0.6, 1) infinite;
  --animate-pulse-fast: pulse 1s cubic-bezier(0.4, 0, 0.6, 1) infinite;
  --animate-bounce-slow: bounce 2s infinite;
  --animate-shimmer: shimmer 2s ease-in-out infinite;
}

/* ===== Base Styles ===== */
@layer base {
  /* Preserve v3 border color default */
  *,
  ::after,
  ::before,
  ::backdrop,
  ::file-selector-button {
    border-color: var(--border);
  }

  /* Base element styling */
  body {
    @apply bg-background text-foreground min-h-screen antialiased;
    font-family:
      "Inter",
      system-ui,
      -apple-system,
      BlinkMacSystemFont,
      "Segoe UI",
      Roboto,
      sans-serif;
  }

  h1,
  h2,
  h3,
  h4,
  h5,
  h6 {
    @apply font-semibold text-foreground;
  }

  /* Links */
  a {
    @apply text-primary hover:underline decoration-transparent hover:decoration-current underline-offset-4 transition-all duration-200;
  }

  /* Fixed header clearance — absolute backgrounds fill from container
     top (unaffected by padding), content pushed below header */
  main > * {
    padding-top: 4.5rem; /* 72px: h-14 + pt-2 + breathing room */
  }

  /* Scoped transition to interactive elements (was global * selector) */
  a,
  button,
  input,
  select,
  textarea,
  [role="button"] {
    transition-property:
      color, background-color, border-color, outline-color, text-decoration-color, fill, stroke;
    transition-duration: 200ms;
    transition-timing-function: ease-in-out;
  }
}

/* ===== Custom Utilities (survive past Phase 4) ===== */
@utility glass {
  background-color: rgb(255 255 255 / 0.7);
  backdrop-filter: blur(16px);
  border: 1px solid rgb(203 213 225 / 0.5);

  &:where(.dark, .dark *) {
    background-color: rgb(30 41 59 / 0.7);
    backdrop-filter: blur(24px);
    border-color: rgb(51 65 85 / 0.5);
  }
}

/* Bold glassmorphism -- the primary glass surface */
@utility glass-bold {
  background-color: rgb(255 255 255 / 0.1);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border: 1px solid rgb(255 255 255 / 0.3);
  box-shadow: inset 0 1px 1px 0 rgb(255 255 255 / 0.15);

  &:where(.dark, .dark *) {
    background-color: rgb(30 41 59 / 0.2);
    border-color: rgb(148 163 184 / 0.15);
    box-shadow: inset 0 1px 1px 0 rgb(255 255 255 / 0.05);
  }
}

/* Mobile-optimized glass (reduced blur for GPU perf) */
@utility glass-mobile {
  background-color: rgb(255 255 255 / 0.1);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgb(255 255 255 / 0.2);

  &:where(.dark, .dark *) {
    background-color: rgb(30 41 59 / 0.2);
    border-color: rgb(148 163 184 / 0.1);
  }
}

/* Claymorphism for interactive elements (raised, tactile feel) */
@utility clay-interactive {
  border-radius: 16px;
  box-shadow:
    inset 0 -3px 6px 0 rgb(0 0 0 / 0.06),
    inset 0 2px 4px 0 rgb(255 255 255 / 0.4),
    0 8px 20px -4px rgb(0 0 0 / 0.12),
    0 2px 4px 0 rgb(0 0 0 / 0.04);

  &:where(.dark, .dark *) {
    box-shadow:
      inset 0 -3px 6px 0 rgb(0 0 0 / 0.2),
      inset 0 2px 4px 0 rgb(255 255 255 / 0.08),
      0 8px 20px -4px rgb(0 0 0 / 0.4),
      0 2px 4px 0 rgb(0 0 0 / 0.15);
  }
}

/* Claymorphism button shadow (no border-radius — buttons control their own) */
@utility clay-btn {
  box-shadow:
    inset 0 -3px 6px 0 rgb(0 0 0 / 0.08),
    inset 0 2px 3px 0 rgb(255 255 255 / 0.4),
    0 6px 16px -4px rgb(0 0 0 / 0.12),
    0 2px 4px 0 rgb(0 0 0 / 0.04);

  &:where(.dark, .dark *) {
    box-shadow:
      inset 0 -3px 6px 0 rgb(0 0 0 / 0.2),
      inset 0 2px 3px 0 rgb(255 255 255 / 0.08),
      0 6px 16px -4px rgb(0 0 0 / 0.35),
      0 2px 4px 0 rgb(0 0 0 / 0.15);
  }
}

/* Clay button pressed state (inverted shadows for pressed-in appearance) */
@utility clay-pressed {
  box-shadow:
    inset 0 2px 6px 0 rgb(0 0 0 / 0.1),
    inset 0 -1px 2px 0 rgb(255 255 255 / 0.2),
    0 2px 4px -2px rgb(0 0 0 / 0.06);

  &:where(.dark, .dark *) {
    box-shadow:
      inset 0 2px 6px 0 rgb(0 0 0 / 0.3),
      inset 0 -1px 2px 0 rgb(255 255 255 / 0.04),
      0 2px 4px -2px rgb(0 0 0 / 0.2);
  }
}

/* Button hover lift with glow (ANIM-02) */
@utility btn-hover-lift {
  transition:
    transform 200ms ease,
    box-shadow 200ms ease;

  &:hover {
    transform: translateY(-2px);
    box-shadow:
      0 4px 12px -2px oklch(from var(--primary) l c h / 0.2),
      inset 0 -3px 6px 0 rgb(0 0 0 / 0.08),
      inset 0 2px 3px 0 rgb(255 255 255 / 0.4),
      0 6px 16px -4px rgb(0 0 0 / 0.12);
  }

  &:where(.dark, .dark *):hover {
    box-shadow:
      0 4px 12px -2px oklch(from var(--primary) l c h / 0.3),
      inset 0 -3px 6px 0 rgb(0 0 0 / 0.2),
      inset 0 2px 3px 0 rgb(255 255 255 / 0.08),
      0 6px 16px -4px rgb(0 0 0 / 0.35);
  }

  &:active {
    transform: translateY(0) scale(0.97);
    transition:
      transform 100ms ease,
      box-shadow 100ms ease;
  }
}

/* Focus ring animation (ANIM-03) */
@utility focus-ring-animate {
  outline: 2px solid transparent;
  outline-offset: 2px;
  transition:
    outline-color 200ms ease,
    outline-offset 200ms ease;

  &:focus-visible {
    outline-color: var(--ring);
    outline-offset: 3px;
  }
}

@utility text-gradient {
  color: transparent;
  background-clip: text;
  background-image: linear-gradient(to right, var(--color-sky-600), var(--color-indigo-600));

  &:where(.dark, .dark *) {
    background-image: linear-gradient(to right, var(--color-sky-400), var(--color-cyan-400));
  }
}

@utility bg-gradient-radial {
  background-image: radial-gradient(var(--tw-gradient-stops));
}

@utility transform-style-3d {
  transform-style: preserve-3d;
}

@utility scrollbar-hide {
  -ms-overflow-style: none;
  scrollbar-width: none;
  &::-webkit-scrollbar {
    display: none;
  }
}

/* ===== Theme Toggle Button ===== */
@layer components {
  .theme-toggle-button:hover {
    --pulse-color: var(--color-sky-500);
    animation: subtle-pulse 1.5s cubic-bezier(0.4, 0, 0.6, 1) infinite;
  }
  .dark .theme-toggle-button:hover {
    --pulse-color: var(--color-sky-400);
  }
}

/* ===== Keyframes ===== */
@keyframes subtle-pulse {
  0%,
  100% {
    box-shadow: 0 0 0 0 color-mix(in oklch, var(--pulse-color) 30%, transparent);
  }
  50% {
    box-shadow: 0 0 0 5px color-mix(in oklch, var(--pulse-color) 0%, transparent);
  }
}

@keyframes shimmer {
  0% {
    transform: translateX(-100%);
  }
  100% {
    transform: translateX(100%);
  }
}

@keyframes mesh-gradient-move {
  0% {
    background-position: 0% 50%;
  }
  50% {
    background-position: 100% 50%;
  }
  100% {
    background-position: 0% 50%;
  }
}