/* ============================================
   USABuyHub - Main Stylesheet
   Modular CSS Architecture - HD Production
   ============================================ */

/* CSS Variables - Premium HD Design */
:root {
    /* Colors - Premium Dark Theme */
    --primary: #00D4AA;
    --primary-dark: #00B894;
    --primary-light: #55EFC4;
    --primary-glow: rgba(0, 212, 170, 0.4);
    --secondary: #6C5CE7;
    --secondary-dark: #5B4CDB;
    --secondary-light: #A29BFE;
    --accent: #FD79A8;
    --warning: #FDCB6E;
    --danger: #FF7675;
    --success: #00B894;
    
    /* Backgrounds */
    --bg-dark: #0A0A0F;
    --bg-darker: #050508;
    --bg-card: #12121A;
    --bg-card-hover: #1A1A25;
    --bg-input: #1E1E2A;
    --bg-elevated: #16161F;
    --bg-gradient: linear-gradient(135deg, #0A0A0F 0%, #1A1A2E 50%, #0A0A0F 100%);
    --bg-gradient-radial: radial-gradient(ellipse at center, #1A1A2E 0%, #0A0A0F 70%);
    
    /* Text */
    --text-primary: #FFFFFF;
    --text-secondary: #B0B0C0;
    --text-muted: #707080;
    --text-disabled: #505060;
    
    /* Borders */
    --border-color: #2A2A3A;
    --border-light: #3A3A4A;
    --border-focus: var(--primary);
    
    /* Shadows - HD Quality */
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.2);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 12px 60px rgba(0, 0, 0, 0.6);
    --shadow-glow: 0 0 40px rgba(0, 212, 170, 0.25);
    --shadow-glow-lg: 0 0 60px rgba(0, 212, 170, 0.35);
    --shadow-inner: inset 0 2px 4px rgba(0, 0, 0, 0.3);
    
    /* Typography */
    --font-main: 'Outfit', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'Space Mono', 'SF Mono', 'Consolas', monospace;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;
    --spacing-xxxl: 4rem;
    
    /* Border Radius - Refined */
    --radius-xs: 4px;
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 50px;
    
    /* Transitions - Smooth */
    --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-bounce: 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-main);
    background: var(--bg-dark);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

/* Background Animation */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(ellipse at 20% 20%, rgba(0, 212, 170, 0.08) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 80%, rgba(108, 92, 231, 0.08) 0%, transparent 50%),
        radial-gradient(ellipse at 50% 50%, rgba(253, 121, 168, 0.05) 0%, transparent 70%);
    pointer-events: none;
    z-index: -1;
}

#app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

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

h1 { font-size: clamp(2rem, 5vw, 3.5rem); }
h2 { font-size: clamp(1.5rem, 4vw, 2.5rem); }
h3 { font-size: clamp(1.25rem, 3vw, 1.75rem); }
h4 { font-size: 1.25rem; }

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

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

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

/* Container */
.container {
    width: 100%;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.container-sm {
    max-width: 800px;
}

.container-lg {
    max-width: 1600px;
}

/* Grid System */
.grid {
    display: grid;
    gap: var(--spacing-lg);
}

.grid-2 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); }

/* Flexbox Utilities */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.flex-wrap { flex-wrap: wrap; }
.items-center { align-items: center; }
.items-start { align-items: flex-start; }
.items-end { align-items: flex-end; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.justify-end { justify-content: flex-end; }
.gap-sm { gap: var(--spacing-sm); }
.gap-md { gap: var(--spacing-md); }
.gap-lg { gap: var(--spacing-lg); }

/* Spacing Utilities */
.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); }
.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); }
.py-sm { padding-top: var(--spacing-sm); padding-bottom: var(--spacing-sm); }
.py-md { padding-top: var(--spacing-md); padding-bottom: var(--spacing-md); }
.py-lg { padding-top: var(--spacing-lg); padding-bottom: var(--spacing-lg); }
.py-xl { padding-top: var(--spacing-xl); padding-bottom: var(--spacing-xl); }
.py-xxl { padding-top: var(--spacing-xxl); padding-bottom: var(--spacing-xxl); }
.px-sm { padding-left: var(--spacing-sm); padding-right: var(--spacing-sm); }
.px-md { padding-left: var(--spacing-md); padding-right: var(--spacing-md); }
.px-lg { padding-left: var(--spacing-lg); padding-right: var(--spacing-lg); }

/* Text Utilities */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }
.text-primary { color: var(--primary); }
.text-secondary { color: var(--text-secondary); }
.text-muted { color: var(--text-muted); }
.text-sm { font-size: 0.875rem; }
.text-lg { font-size: 1.125rem; }
.text-xl { font-size: 1.25rem; }
.font-medium { font-weight: 500; }
.font-semibold { font-weight: 600; }
.font-bold { font-weight: 700; }
.font-mono { font-family: var(--font-mono); }

/* Visibility */
.hidden { display: none !important; }
.visible { visibility: visible; }
.invisible { visibility: hidden; }

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

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInDown {
    from { opacity: 0; transform: translateY(-20px); }
    to { opacity: 1; transform: translateY(0); }
}

@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 scaleIn {
    from { opacity: 0; transform: scale(0.95); }
    to { opacity: 1; transform: scale(1); }
}

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

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

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

.animate-fadeIn { animation: fadeIn var(--transition-normal) ease forwards; }
.animate-fadeInUp { animation: fadeInUp var(--transition-normal) ease forwards; }
.animate-fadeInDown { animation: fadeInDown var(--transition-normal) ease forwards; }
.animate-slideInLeft { animation: slideInLeft var(--transition-normal) ease forwards; }
.animate-slideInRight { animation: slideInRight var(--transition-normal) ease forwards; }
.animate-scaleIn { animation: scaleIn var(--transition-normal) ease forwards; }
.animate-pulse { animation: pulse 2s ease-in-out infinite; }
.animate-spin { animation: spin 1s linear infinite; }
.animate-float { animation: float 3s ease-in-out infinite; }

/* Delay utilities for staggered animations */
.delay-1 { animation-delay: 0.1s; }
.delay-2 { animation-delay: 0.2s; }
.delay-3 { animation-delay: 0.3s; }
.delay-4 { animation-delay: 0.4s; }
.delay-5 { animation-delay: 0.5s; }

/* Scrollbar Styling */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-dark);
}

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--border-light);
}

/* Selection */
::selection {
    background: var(--primary);
    color: var(--bg-dark);
}

/* Focus Visible */
:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* Page Transitions */
.page {
    opacity: 0;
    animation: fadeInUp 0.4s ease forwards;
}

.page-enter {
    animation: fadeInUp 0.4s ease forwards;
}

.page-exit {
    animation: fadeIn 0.2s ease reverse forwards;
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: 0 var(--spacing-md);
    }
    
    .hide-mobile {
        display: none !important;
    }
}

@media (min-width: 769px) {
    .hide-desktop {
        display: none !important;
    }
}