/* ===================================
   AI Text Humanizer - Design System
   =================================== */

/* Import Google Fonts */
@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@400;500;600;700&family=Inter:wght@300;400;500;600;700&display=swap');

/* ===================================
   CSS Custom Properties
   =================================== */
:root {
  /* Colors - Purple/Blue Tech Gradient Theme */
  --color-primary: hsl(260, 85%, 65%);
  --color-primary-light: hsl(260, 85%, 75%);
  --color-primary-dark: hsl(260, 85%, 55%);
  
  --color-secondary: hsl(220, 90%, 60%);
  --color-secondary-light: hsl(220, 90%, 70%);
  
  --color-accent: hsl(310, 85%, 65%);
  --color-accent-neon: hsl(310, 100%, 70%);
  
  --color-success: hsl(150, 70%, 55%);
  --color-warning: hsl(45, 95%, 60%);
  --color-danger: hsl(0, 85%, 65%);
  
  /* Backgrounds */
  --color-bg-primary: hsl(240, 15%, 8%);
  --color-bg-secondary: hsl(240, 12%, 12%);
  --color-bg-tertiary: hsl(240, 10%, 16%);
  
  /* Glass Effects */
  --glass-bg: rgba(255, 255, 255, 0.05);
  --glass-border: rgba(255, 255, 255, 0.1);
  --glass-shadow: rgba(0, 0, 0, 0.3);
  
  /* Text Colors */
  --color-text-primary: hsl(0, 0%, 98%);
  --color-text-secondary: hsl(0, 0%, 75%);
  --color-text-muted: hsl(0, 0%, 55%);
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
  --gradient-accent: linear-gradient(135deg, var(--color-accent) 0%, var(--color-primary) 100%);
  --gradient-hero: linear-gradient(180deg, var(--color-bg-primary) 0%, var(--color-bg-secondary) 100%);
  --gradient-glow: radial-gradient(circle at 50% 50%, rgba(138, 92, 246, 0.15) 0%, transparent 70%);
  
  /* Typography */
  --font-heading: 'Space Grotesk', sans-serif;
  --font-body: 'Inter', sans-serif;
  
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 2rem;
  --font-size-4xl: 2.5rem;
  --font-size-5xl: 3rem;
  --font-size-6xl: 4rem;
  
  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 0.75rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  --spacing-4xl: 6rem;
  
  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.4);
  --shadow-glow: 0 0 30px rgba(138, 92, 246, 0.3);
  
  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 250ms ease-in-out;
  --transition-slow: 400ms ease-in-out;
  
  /* Z-index */
  --z-dropdown: 1000;
  --z-sticky: 1020;
  --z-fixed: 1030;
  --z-modal: 1040;
  --z-tooltip: 1050;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-text-primary);
  background: var(--color-bg-primary);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ===================================
   Typography
   =================================== */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: var(--spacing-md);
  color: var(--color-text-primary);
}

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
h3 { font-size: var(--font-size-3xl); }
h4 { font-size: var(--font-size-2xl); }
h5 { font-size: var(--font-size-xl); }
h6 { font-size: var(--font-size-lg); }

p {
  margin-bottom: var(--spacing-md);
  color: var(--color-text-secondary);
}

a {
  color: var(--color-primary-light);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-accent);
}

/* ===================================
   Layout Components
   =================================== */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.container-wide {
  max-width: 1400px;
}

.section {
  padding: var(--spacing-4xl) 0;
  position: relative;
}

.section-sm {
  padding: var(--spacing-3xl) 0;
}

/* ===================================
   Navigation
   =================================== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-fixed);
  background: rgba(15, 15, 25, 0.8);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--glass-border);
  transition: all var(--transition-base);
}

.navbar.scrolled {
  background: rgba(15, 15, 25, 0.95);
  box-shadow: var(--shadow-lg);
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-lg) var(--spacing-lg);
  max-width: 1400px;
  margin: 0 auto;
}

.nav-logo {
  font-family: var(--font-heading);
  font-size: var(--font-size-xl);
  font-weight: 700;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: var(--spacing-xl);
  align-items: center;
}

.nav-link {
  color: var(--color-text-secondary);
  font-weight: 500;
  transition: all var(--transition-fast);
  position: relative;
  padding: var(--spacing-xs) 0;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-primary);
  transition: width var(--transition-base);
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-text-primary);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--spacing-xs);
}

.nav-toggle span {
  width: 25px;
  height: 3px;
  background: var(--color-text-primary);
  border-radius: var(--radius-full);
  transition: all var(--transition-base);
}

/* ===================================
   Buttons
   =================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) var(--spacing-xl);
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  font-weight: 600;
  border: none;
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.1);
  transform: translate(-50%, -50%);
  transition: width var(--transition-slow), height var(--transition-slow);
}

.btn:hover::before {
  width: 300px;
  height: 300px;
}

.btn-primary {
  background: var(--gradient-primary);
  color: white;
  box-shadow: 0 4px 15px rgba(138, 92, 246, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(138, 92, 246, 0.4);
}

.btn-secondary {
  background: var(--glass-bg);
  color: var(--color-text-primary);
  border: 1px solid var(--glass-border);
  backdrop-filter: blur(10px);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: var(--color-primary);
}

.btn-outline {
  background: transparent;
  color: var(--color-primary-light);
  border: 2px solid var(--color-primary);
}

.btn-outline:hover {
  background: var(--color-primary);
  color: white;
}

.btn-lg {
  padding: var(--spacing-lg) var(--spacing-2xl);
  font-size: var(--font-size-lg);
}

.btn-sm {
  padding: var(--spacing-sm) var(--spacing-lg);
  font-size: var(--font-size-sm);
}

/* ===================================
   Cards & Glass Effects
   =================================== */
.card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  backdrop-filter: blur(20px);
  transition: all var(--transition-base);
}

.card:hover {
  transform: translateY(-5px);
  border-color: var(--color-primary);
  box-shadow: var(--shadow-glow);
}

.card-glass {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(255, 255, 255, 0.08);
  backdrop-filter: blur(30px);
}

/* ===================================
   Form Elements
   =================================== */
.form-group {
  margin-bottom: var(--spacing-lg);
}

.form-label {
  display: block;
  margin-bottom: var(--spacing-sm);
  font-weight: 500;
  color: var(--color-text-primary);
}

.form-input,
.form-textarea,
.form-select {
  width: 100%;
  padding: var(--spacing-md);
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  color: var(--color-text-primary);
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  transition: all var(--transition-base);
  backdrop-filter: blur(10px);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(138, 92, 246, 0.1);
}

.form-textarea {
  resize: vertical;
  min-height: 120px;
}

/* ===================================
   Footer
   =================================== */
.footer {
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--glass-border);
  padding: var(--spacing-3xl) 0 var(--spacing-xl);
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-2xl);
  margin-bottom: var(--spacing-2xl);
}

.footer-section h4 {
  margin-bottom: var(--spacing-lg);
  color: var(--color-text-primary);
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: var(--spacing-sm);
}

.footer-links a {
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--color-primary-light);
}

.footer-bottom {
  text-align: center;
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--glass-border);
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
}

/* ===================================
   Animations
   =================================== */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideInLeft {
  from {
    opacity: 0;
    transform: translateX(-30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

@keyframes glow {
  0%, 100% {
    box-shadow: 0 0 20px rgba(138, 92, 246, 0.3);
  }
  50% {
    box-shadow: 0 0 40px rgba(138, 92, 246, 0.6);
  }
}

.animate-fadeInUp {
  animation: fadeInUp 0.6s ease-out;
}

.animate-fadeIn {
  animation: fadeIn 0.6s ease-out;
}

.animate-slideInLeft {
  animation: slideInLeft 0.6s ease-out;
}

.animate-slideInRight {
  animation: slideInRight 0.6s ease-out;
}

/* ===================================
   Utility Classes
   =================================== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.text-gradient {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }
.mt-2xl { margin-top: var(--spacing-2xl); }

.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }
.mb-2xl { margin-bottom: var(--spacing-2xl); }

.hidden { display: none; }
.visible { display: block; }

/* ===================================
   Responsive Design
   =================================== */
@media (max-width: 768px) {
  :root {
    --font-size-5xl: 2.5rem;
    --font-size-4xl: 2rem;
    --font-size-3xl: 1.75rem;
  }
  
  .nav-menu {
    position: fixed;
    top: 70px;
    left: -100%;
    width: 100%;
    height: calc(100vh - 70px);
    background: rgba(15, 15, 25, 0.98);
    backdrop-filter: blur(20px);
    flex-direction: column;
    justify-content: flex-start;
    padding: var(--spacing-2xl);
    gap: var(--spacing-lg);
    transition: left var(--transition-base);
  }
  
  .nav-menu.active {
    left: 0;
  }
  
  .nav-toggle {
    display: flex;
  }
  
  .nav-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }
  
  .nav-toggle.active span:nth-child(2) {
    opacity: 0;
  }
  
  .nav-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
  }
  
  .section {
    padding: var(--spacing-3xl) 0;
  }
  
  .footer-content {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--spacing-md);
  }
  
  .btn-lg {
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-base);
  }
}