/*
 * Path: /public/assets/css/styles.css
 * Function: Global design system styles for AI Digital Human Platform
 * Dependencies: None (self-contained CSS variables)
 * Priority: Main (must be loaded before app.js)
 */

:root {
  /* System Configuration */
  --sys-type: tech;
  --theme-mode: dark;
  --motion-level: standard;

  /* Brand Color Mapping */
  --_tech-primary: #8B5CF6;
  --_tech-secondary: #1E1B4B;
  --_tech-accent: #06B6D4;

  --brand-primary: var(--_tech-primary);
  --brand-secondary: var(--_tech-secondary);
  --brand-accent: var(--_tech-accent);

  /* Semantic Colors */
  --bg-default: #0a0a0f;
  --bg-subtle: color-mix(in srgb, var(--bg-default) 95%, var(--brand-primary));
  --bg-hover: color-mix(in srgb, var(--bg-default) 90%, var(--brand-primary));
  --fg-default: #fafafa;
  --fg-muted: color-mix(in srgb, var(--fg-default) 60%, var(--bg-default));
  --fg-inverse: var(--bg-default);
  --surface-default: color-mix(in srgb, var(--bg-default) 97%, var(--brand-primary));
  --surface-elevated: color-mix(in srgb, var(--bg-default) 92%, white);
  --surface-overlay: color-mix(in srgb, var(--bg-default) 50%, black);
  --border-default: color-mix(in srgb, var(--fg-default) 10%, transparent);
  --border-hover: color-mix(in srgb, var(--brand-primary) 30%, transparent);
  --border-active: var(--brand-primary);
  --status-success: #10B981;
  --status-warning: #F59E0B;
  --status-error: #EF4444;
  --status-info: var(--brand-accent);

  /* Component Colors */
  --color-primary: var(--brand-primary);
  --color-primary-fg: var(--fg-default);
  --color-secondary: var(--surface-elevated);
  --color-secondary-fg: var(--fg-default);
  --color-accent: var(--brand-accent);
  --color-accent-fg: var(--bg-default);
  --color-muted: var(--surface-default);
  --color-muted-fg: var(--fg-muted);
  --color-card: var(--surface-default);
  --color-card-fg: var(--fg-default);
  --color-border: var(--border-default);
  --color-input: var(--border-default);
  --color-ring: var(--brand-accent);
  --color-destructive: var(--status-error);
  --color-destructive-fg: var(--fg-default);

  /* Gradients */
  --gradient-primary: linear-gradient(135deg, var(--brand-primary) 0%, var(--brand-accent) 100%);
  --gradient-surface: linear-gradient(180deg, var(--surface-elevated) 0%, var(--surface-default) 100%);
  --gradient-mesh: radial-gradient(at 0% 0%, color-mix(in srgb, var(--brand-primary) 40%, transparent) 0%, transparent 50%), radial-gradient(at 100% 0%, color-mix(in srgb, var(--brand-accent) 30%, transparent) 0%, transparent 50%), radial-gradient(at 100% 100%, color-mix(in srgb, var(--brand-secondary) 30%, transparent) 0%, transparent 50%), radial-gradient(at 0% 100%, color-mix(in srgb, var(--brand-primary) 20%, transparent) 0%, transparent 50%);

  /* Typography */
  --font-sans: 'Inter', system-ui, sans-serif;
  --font-display: 'Plus Jakarta Sans', var(--font-sans);
  --font-mono: 'JetBrains Mono', monospace;
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;
  --text-5xl: 3rem;
  --text-6xl: 3.75rem;
  --text-hero: clamp(3rem, 8vw, 6rem);
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;
  --font-black: 900;
  --leading-tight: 1.1;
  --leading-snug: 1.375;
  --leading-normal: 1.6;
  --leading-relaxed: 1.8;

  /* Spacing */
  --space-0: 0;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  --density: 1;

  /* Navigation Height & Safe Top - Critical for content visibility */
  --nav-height-mobile: 3.5rem;
  --nav-height-tablet: 4rem;
  --nav-height-desktop: 4.5rem;
  --nav-height: var(--nav-height-mobile);
  
  --safe-top: calc(var(--nav-height) + var(--space-4));
  --safe-top-tablet: calc(var(--nav-height-tablet) + var(--space-6));
  --safe-top-desktop: calc(var(--nav-height-desktop) + var(--space-8));

  /* Shape */
  --radius-none: 0;
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-3xl: 2rem;
  --radius-full: 9999px;

  /* Motion */
  --duration-instant: 0ms;
  --duration-fast: 150ms;
  --duration-normal: 300ms;
  --duration-slow: 500ms;
  --duration-slower: 800ms;
  --ease-default: cubic-bezier(0.4, 0, 0.2, 1);
  --ease-in: cubic-bezier(0.4, 0, 1, 1);
  --ease-out: cubic-bezier(0, 0, 0.2, 1);
  --ease-bounce: cubic-bezier(0.68, -0.55, 0.265, 1.55);
  --ease-smooth: cubic-bezier(0.16, 1, 0.3, 1);

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.4), 0 2px 4px -2px rgb(0 0 0 / 0.3);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.4), 0 4px 6px -4px rgb(0 0 0 / 0.3);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.5), 0 8px 10px -6px rgb(0 0 0 / 0.3);
  --glow-sm: 0 0 20px color-mix(in srgb, var(--brand-primary) 30%, transparent);
  --glow-md: 0 0 40px color-mix(in srgb, var(--brand-primary) 40%, transparent);
  --glow-lg: 0 0 60px color-mix(in srgb, var(--brand-primary) 50%, transparent);

  /* Z-Index */
  --z-base: 0;
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-modal-backdrop: 300;
  --z-modal: 400;
  --z-popover: 500;
  --z-tooltip: 600;
}

/* Light Mode */
@media (prefers-color-scheme: light) {
  :root {
    --bg-default: #ffffff;
    --bg-subtle: color-mix(in srgb, var(--bg-default) 98%, var(--brand-primary));
    --bg-hover: color-mix(in srgb, var(--bg-default) 95%, var(--brand-primary));
    --fg-default: #0a0a0f;
    --fg-muted: color-mix(in srgb, var(--fg-default) 50%, var(--bg-default));
    --surface-default: color-mix(in srgb, var(--bg-default) 99%, var(--brand-primary));
    --surface-elevated: color-mix(in srgb, var(--bg-default) 96%, black);
    --border-default: color-mix(in srgb, var(--fg-default) 8%, transparent);
    --border-hover: color-mix(in srgb, var(--brand-primary) 40%, transparent);
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.05);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.05);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.05);
  }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  :root {
    --duration-fast: 0.01ms;
    --duration-normal: 0.01ms;
    --duration-slow: 0.01ms;
    --duration-slower: 0.01ms;
  }
}

/* Base Reset */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  /* Prevent content from being hidden behind fixed navbar on anchor scroll */
  scroll-padding-top: var(--safe-top);
}

body {
  font-family: var(--font-sans);
  background: var(--bg-default);
  color: var(--fg-default);
  line-height: var(--leading-normal);
  -webkit-font-smoothing: antialiased;
  font-feature-settings: "cv02", "cv03", "cv04", "cv11";
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Button System */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: calc(var(--space-3) * var(--density)) calc(var(--space-6) * var(--density));
  border: 1px solid transparent;
  border-radius: var(--radius-lg);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  line-height: var(--leading-tight);
  cursor: pointer;
  position: relative;
  overflow: hidden;
  transition: transform var(--duration-fast) var(--ease-default), box-shadow var(--duration-fast) var(--ease-default), background-color var(--duration-fast) var(--ease-default);
  text-decoration: none;
  white-space: nowrap;
  /* Ensure touch target is at least 48x48px */
  min-height: 48px;
  min-width: 48px;
}

.btn:active {
  transform: scale(0.96);
}

.btn--primary {
  background: var(--color-primary);
  color: var(--color-primary-fg);
  box-shadow: var(--glow-sm);
}

.btn--primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--glow-md), var(--shadow-lg);
  filter: brightness(1.1);
}

.btn--secondary {
  background: var(--color-secondary);
  color: var(--color-secondary-fg);
  border-color: var(--color-border);
}

.btn--secondary:hover {
  background: var(--bg-hover);
  border-color: var(--border-hover);
  transform: translateY(-2px);
}

.btn--gradient {
  background: var(--gradient-primary);
  color: var(--fg-default);
  position: relative;
  z-index: 1;
}

.btn--gradient::before {
  content: '';
  position: absolute;
  inset: -2px;
  background: var(--gradient-mesh);
  border-radius: inherit;
  z-index: -1;
  opacity: 0;
  filter: blur(8px);
  transition: opacity var(--duration-normal) var(--ease-default);
}

.btn--gradient:hover::before {
  opacity: 0.6;
}

.btn--ghost {
  background: transparent;
  color: var(--fg-default);
  border-color: var(--color-border);
}

.btn--ghost:hover {
  background: var(--surface-default);
  border-color: var(--border-hover);
}

.btn--destructive {
  background: var(--color-destructive);
  color: var(--color-destructive-fg);
}

.btn--destructive:hover {
  animation: wiggle var(--duration-normal) var(--ease-default);
}

.btn:disabled, .btn[aria-disabled="true"] {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none !important;
  filter: none !important;
  box-shadow: none !important;
}

/* Card System */
.card {
  background: var(--color-card);
  color: var(--color-card-fg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: calc(var(--space-6) * var(--density));
  transition: transform var(--duration-normal) var(--ease-default), box-shadow var(--duration-normal) var(--ease-default), border-color var(--duration-fast) var(--ease-default);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg), var(--glow-sm);
  border-color: var(--border-hover);
}

.card--glass {
  background: color-mix(in srgb, var(--color-card) 80%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.card--interactive {
  cursor: pointer;
}

/* Navbar - Fixed positioning */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-sticky);
  height: var(--nav-height); /* Explicit height for safe-top calculation */
  background: color-mix(in srgb, var(--bg-default) 80%, transparent);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border);
  padding: 0 calc(var(--space-6) * var(--density));
  display: flex;
  align-items: center;
}

.navbar__container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.navbar__brand {
  font-size: var(--text-xl);
  font-weight: var(--font-black);
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
  text-decoration: none;
}

.navbar__nav {
  display: flex;
  gap: calc(var(--space-8) * var(--density));
  list-style: none;
  align-items: center;
}

.navbar__link {
  color: var(--fg-default);
  text-decoration: none;
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  position: relative;
  padding: var(--space-2) 0;
  transition: color var(--duration-fast) var(--ease-default);
}

.navbar__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-primary);
  transition: width var(--duration-normal) var(--ease-default);
}

.navbar__link:hover {
  color: var(--color-primary);
}

.navbar__link:hover::after {
  width: 100%;
}

.navbar__link--active {
  color: var(--color-primary);
}

.navbar__link--active::after {
  width: 100%;
}

/* Main Content Container - Prevents content from being hidden behind navbar */
.page-wrapper {
  padding-top: var(--safe-top); /* Key: Offsets content by navbar height */
  flex-grow: 1; /* Ensures footer stays at the bottom */
  width: 100%;
}

/* Hero Section - Uses safe-top */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--safe-top) calc(var(--space-6) * var(--density)) calc(var(--space-24) * var(--density));
  overflow: hidden;
  background: var(--bg-default);
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--gradient-mesh);
  opacity: 0.6;
  animation: mesh-shift 30s linear infinite;
}

.hero__content {
  position: relative;
  z-index: 10;
  text-align: center;
  max-width: 900px;
  animation: fade-in-up var(--duration-slow) var(--ease-smooth) both;
}

.hero__title {
  font-size: var(--text-hero);
  font-weight: var(--font-black);
  line-height: var(--leading-tight);
  letter-spacing: -0.03em;
  margin-bottom: calc(var(--space-6) * var(--density));
  background: linear-gradient(135deg, var(--fg-default) 0%, var(--brand-primary) 50%, var(--brand-accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero__description {
  font-size: var(--text-lg);
  line-height: var(--leading-relaxed);
  color: var(--fg-muted);
  margin-bottom: calc(var(--space-8) * var(--density));
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

/* Input Field */
.input {
  width: 100%;
  padding: calc(var(--space-3) * var(--density)) calc(var(--space-4) * var(--density));
  background: var(--bg-default);
  border: 1px solid var(--color-input);
  border-radius: var(--radius-lg);
  color: var(--fg-default);
  font-size: var(--text-sm);
  line-height: var(--leading-normal);
  outline: none;
  transition: border-color var(--duration-fast) var(--ease-default), box-shadow var(--duration-fast) var(--ease-default), transform var(--duration-fast) var(--ease-default);
}

.input::placeholder {
  color: var(--fg-muted);
}

.input:focus {
  border-color: var(--color-ring);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-ring) 20%, transparent), var(--glow-sm);
  transform: translateY(-1px);
}

.input:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Skeleton Loader */
.skeleton {
  background: linear-gradient(90deg, var(--color-muted) 25%, color-mix(in srgb, var(--brand-primary) 10%, var(--color-muted)) 50%, var(--color-muted) 75%);
  background-size: 200% 100%;
  border-radius: var(--radius-md);
  animation: shimmer var(--duration-slow) linear infinite;
}

/* Modal */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: var(--surface-overlay);
  backdrop-filter: blur(8px);
  z-index: var(--z-modal-backdrop);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--duration-normal) var(--ease-default);
}

.modal-backdrop--open {
  opacity: 1;
  pointer-events: all;
}

.modal {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%) scale(0.95);
  background: color-mix(in srgb, var(--color-card) 95%, transparent);
  border: 1px solid var(--border-hover);
  border-radius: var(--radius-2xl);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  box-shadow: var(--shadow-xl), var(--glow-md);
  padding: calc(var(--space-8) * var(--density));
  max-width: 500px;
  width: 90%;
  z-index: var(--z-modal);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--duration-normal) var(--ease-default), transform var(--duration-normal) var(--ease-bounce);
}

.modal-backdrop--open .modal {
  opacity: 1;
  pointer-events: all;
  transform: translate(-50%, -50%) scale(1);
}

/* Footer */
.footer {
  margin-top: auto;
  background: color-mix(in srgb, var(--bg-default) 95%, var(--brand-secondary));
  border-top: 1px solid var(--border-default);
  padding: calc(var(--space-12) * var(--density)) calc(var(--space-6) * var(--density)) calc(var(--space-6) * var(--density));
  position: relative;
  overflow: hidden;
}

.footer::before {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--gradient-mesh);
  opacity: 0.2;
  z-index: 0;
}

.footer__container {
  max-width: 1200px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.footer__top {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: calc(var(--space-8) * var(--density));
  margin-bottom: calc(var(--space-10) * var(--density));
}

.footer__brand {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.footer__logo {
  font-size: var(--text-xl);
  font-weight: var(--font-black);
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
  text-decoration: none;
  display: inline-block;
}

.footer__description {
  font-size: var(--text-sm);
  color: var(--fg-muted);
  line-height: var(--leading-relaxed);
  max-width: 280px;
}

.footer__social {
  display: flex;
  gap: var(--space-4);
  margin-top: var(--space-4);
}

.footer__social-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: calc(var(--space-8) * var(--density));
  height: calc(var(--space-8) * var(--density));
  border-radius: var(--radius-full);
  background: var(--surface-default);
  color: var(--fg-default);
  transition: transform var(--duration-fast) var(--ease-default), background var(--duration-fast) var(--ease-default), box-shadow var(--duration-fast) var(--ease-default);
}

.footer__social-link:hover {
  transform: translateY(-2px);
  background: var(--gradient-primary);
  box-shadow: var(--glow-sm);
}

.footer__column-title {
  font-size: var(--text-base);
  font-weight: var(--font-semibold);
  margin-bottom: calc(var(--space-4) * var(--density));
  color: var(--fg-default);
}

.footer__links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: calc(var(--space-2) * var(--density));
}

.footer__link {
  color: var(--fg-muted);
  text-decoration: none;
  font-size: var(--text-sm);
  transition: color var(--duration-fast) var(--ease-default), transform var(--duration-fast) var(--ease-default);
  display: inline-block;
}

.footer__link:hover {
  color: var(--brand-primary);
  transform: translateX(2px);
}

.footer__bottom {
  border-top: 1px solid var(--border-default);
  padding-top: calc(var(--space-6) * var(--density));
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: calc(var(--space-4) * var(--density));
}

.footer__copyright {
  font-size: var(--text-xs);
  color: var(--fg-muted);
}

.footer__legal {
  display: flex;
  gap: calc(var(--space-6) * var(--density));
}

.footer__legal-link {
  font-size: var(--text-xs);
  color: var(--fg-muted);
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-default);
}

.footer__legal-link:hover {
  color: var(--brand-primary);
}

/* Animation Keyframes */
@keyframes fade-in-up {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pop-in {
  0% {
    opacity: 0;
    transform: scale(0.9);
  }
  70% {
    transform: scale(1.02);
  }
  100% {
    opacity: 1;
    transform: scale(1);
  }
}

@keyframes shimmer {
  0% {
    background-position: 200% 0;
  }
  100% {
    background-position: -200% 0;
  }
}

@keyframes mesh-shift {
  0%, 100% {
    transform: translate(0, 0) scale(1);
  }
  25% {
    transform: translate(2%, 2%) scale(1.05);
  }
  50% {
    transform: translate(-1%, 3%) scale(1);
  }
  75% {
    transform: translate(3%, -2%) scale(1.02);
  }
}

@keyframes wiggle {
  0%, 100% {
    transform: translateX(0);
  }
  25% {
    transform: translateX(-4px) rotate(-1deg);
  }
  75% {
    transform: translateX(4px) rotate(1deg);
  }
}

@keyframes float {
  0%, 100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-20px);
  }
}

/* Utility Classes */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 calc(var(--space-6) * var(--density));
}

/* Responsive Optimizations */
@media (min-width: 768px) {
  :root {
    --nav-height: var(--nav-height-tablet);
    --safe-top: var(--safe-top-tablet);
    --density: 0.9;
  }

  .hero__title {
    font-size: clamp(2rem, 10vw, 3rem);
  }
  
  .footer__bottom {
    flex-direction: row;
  }
}

@media (min-width: 1200px) {
  :root {
    --nav-height: var(--nav-height-desktop);
    --safe-top: var(--safe-top-desktop);
    --density: 0.9;
  }
}

@media (max-width: 767px) {
  :root {
    --density: 1.0;
  }

  .navbar__nav {
    display: none; /* Hide main nav on mobile, use a hamburger menu instead */
  }

  .hero {
    padding: var(--safe-top) calc(var(--space-4) * var(--density)) calc(var(--space-16) * var(--density));
  }

  .hero__description {
    font-size: var(--text-base);
  }

  .footer {
    padding: calc(var(--space-8) * var(--density)) calc(var(--space-4) * var(--density)) calc(var(--space-4) * var(--density));
  }

  .footer__bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}