/* ===================================
   CSS Variables & Design System
   =================================== */
:root {
    /* Colors */
    --color-primary: #6B46C1;
    --color-primary-light: #8B5CF6;
    --color-primary-dark: #553C9A;
    --color-secondary: #F59E0B;
    --color-secondary-light: #FBBF24;
    --color-accent: #14B8A6;
    --color-accent-light: #2DD4BF;
    
    --color-bg-dark: #0F172A;
    --color-bg-medium: #1E293B;
    --color-bg-light: #334155;
    --color-surface: #1F2937;
    --color-surface-light: #374151;
    
    --color-text-primary: #F3F4F6;
    --color-text-secondary: #D1D5DB;
    --color-text-muted: #9CA3AF;
    
    --color-success: #10B981;
    --color-error: #EF4444;
    --color-warning: #F59E0B;
    
    /* Typography */
    --font-display: 'Playfair Display', 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: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --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, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --shadow-glow: 0 0 20px rgba(107, 70, 193, 0.3);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 300ms ease-in-out;
    --transition-slow: 500ms ease-in-out;
}

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

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

body {
    font-family: var(--font-body);
    background: linear-gradient(135deg, var(--color-bg-dark) 0%, var(--color-bg-medium) 100%);
    color: var(--color-text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

/* ===================================
   Layout
   =================================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-md);
}

.screen {
    display: none;
    min-height: 100vh;
    animation: fadeIn 0.3s ease-in-out;
}

.screen.active {
    display: block;
}

.screen-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.screen-header h2 {
    font-family: var(--font-display);
    font-size: var(--font-size-3xl);
    color: var(--color-text-primary);
}

/* ===================================
   Hero Section
   =================================== */
.hero {
    text-align: center;
    padding: var(--spacing-3xl) 0 var(--spacing-2xl);
}

.hero-title {
    font-family: var(--font-display);
    font-size: var(--font-size-5xl);
    font-weight: 900;
    background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-md);
    text-shadow: 0 0 30px rgba(107, 70, 193, 0.5);
}

.hero-subtitle {
    font-size: var(--font-size-xl);
    color: var(--color-text-secondary);
    font-weight: 500;
}

/* ===================================
   User Status Card
   =================================== */
.user-status-card {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
}

.status-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
}

.status-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.status-value {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--color-secondary);
}

/* ===================================
   Experience Progress
   =================================== */
.exp-progress {
    margin-bottom: var(--spacing-xl);
}

.exp-bar {
    width: 100%;
    height: 24px;
    background: var(--color-surface);
    border-radius: var(--radius-full);
    overflow: hidden;
    position: relative;
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.3);
}

.exp-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--color-primary) 0%, var(--color-accent) 100%);
    border-radius: var(--radius-full);
    transition: width var(--transition-base);
    box-shadow: 0 0 10px rgba(107, 70, 193, 0.5);
}

.exp-text {
    text-align: center;
    margin-top: var(--spacing-sm);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

/* ===================================
   Daily Challenge Banner
   =================================== */
.daily-challenge-banner {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.2) 0%, rgba(251, 191, 36, 0.1) 100%);
    border: 2px solid var(--color-secondary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
    transition: transform var(--transition-base);
}

.daily-challenge-banner:hover {
    transform: translateY(-2px);
}

.banner-icon {
    font-size: var(--font-size-3xl);
}

.banner-content h3 {
    font-size: var(--font-size-lg);
    color: var(--color-secondary);
    margin-bottom: var(--spacing-xs);
}

.banner-content p {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.btn-challenge {
    margin-left: auto;
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--color-secondary);
    color: var(--color-bg-dark);
    border: none;
    border-radius: var(--radius-md);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
}

.btn-challenge:hover {
    background: var(--color-secondary-light);
    transform: scale(1.05);
}

/* ===================================
   Main Menu
   =================================== */
.main-menu {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
}

.menu-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-xl);
    border: none;
    border-radius: var(--radius-xl);
    font-family: var(--font-body);
    font-size: var(--font-size-lg);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.menu-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, transparent 0%, rgba(255, 255, 255, 0.1) 100%);
    opacity: 0;
    transition: opacity var(--transition-base);
}

.menu-btn:hover::before {
    opacity: 1;
}

.menu-btn:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.btn-icon {
    font-size: var(--font-size-4xl);
}

/* ===================================
   Buttons
   =================================== */
.btn-primary {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    color: var(--color-text-primary);
    box-shadow: var(--shadow-glow);
}

.btn-secondary {
    background: var(--color-surface);
    color: var(--color-text-primary);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.btn-back {
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--color-surface);
    color: var(--color-text-primary);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    cursor: pointer;
    transition: all var(--transition-base);
}

.btn-back:hover {
    background: var(--color-surface-light);
    transform: translateX(-4px);
}

/* ===================================
   Responsive Design
   =================================== */
@media (max-width: 768px) {
    .hero-title {
        font-size: var(--font-size-4xl);
    }
    
    .hero-subtitle {
        font-size: var(--font-size-lg);
    }
    
    .user-status-card {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .main-menu {
        grid-template-columns: 1fr;
    }
    
    .container {
        padding: var(--spacing-lg) var(--spacing-md);
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: var(--font-size-3xl);
    }
    
    .status-value {
        font-size: var(--font-size-2xl);
    }
    
    .daily-challenge-banner {
        flex-direction: column;
        text-align: center;
    }
    
    .btn-challenge {
        margin-left: 0;
        width: 100%;
    }
}