:root {
    /* Color Palette */
    --bg-color: #0F172A;
    --card-bg: #1E293B;
    --text-color: #E2E8F0;
    --accent-color: #38BDF8;
    --button-color: #0EA5E9;
    --secondary-button-color: #6366F1;
    --success-color: #22C55E;
    --warning-color: #F59E0B;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 1rem;
    --radius-lg: 1.25rem;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.2);
}

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

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

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Header Styles */
header {
    padding: var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: rgba(30, 41, 59, 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-color);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.back-button {
    background-color: transparent;
    color: var(--text-color);
    border: 1px solid rgba(255, 255, 255, 0.1);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 0.9rem;
}

.back-button:hover {
    background-color: rgba(56, 189, 248, 0.1);
    color: var(--accent-color);
    border-color: var(--accent-color);
    transform: translateX(-2px);
}

/* Container & Card Layout */
.container {
    flex-grow: 1;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 350px), 1fr));
    gap: var(--spacing-xl);
    padding: var(--spacing-xl) var(--spacing-md);
    max-width: 1400px;
    margin: 0 auto;
    width: 100%;
}

.card {
    background-color: var(--card-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
    position: relative;
    overflow: hidden;
    height: 100%;
}

.card::before {
    content: '';
    position: absolute;
    top: -100%;
    left: -100%;
    width: 300%;
    height: 300%;
    background: radial-gradient(
        circle,
        rgba(56, 189, 248, 0.1) 0%,
        rgba(56, 189, 248, 0) 70%
    );
    transform: rotate(45deg);
    z-index: 0;
    transition: transform var(--transition-slow);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.card:hover::before {
    transform: rotate(45deg) translate(10%, 10%);
}

/* Card Content Styles */
.card-content {
    position: relative;
    z-index: 1;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.card h2 {
    color: var(--accent-color);
    font-size: 1.5rem;
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.version-box {
    background: linear-gradient(135deg, var(--accent-color), var(--secondary-button-color));
    border-radius: var(--radius-full);
    padding: var(--spacing-xs) var(--spacing-md);
    font-size: 0.875rem;
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--bg-color);
    font-weight: 600;
    align-self: flex-start;
}

/* Button Styles */
.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    width: 100%;
    height: 3rem;
    font-size: 1rem;
    font-weight: 600;
    background-color: var(--button-color);
    color: var(--bg-color);
    text-decoration: none;
    border: none;
    border-radius: var(--radius-full);
    margin-top: auto;
    transition: all var(--transition-normal);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.button::after {
    content: '';
    position: absolute;
    width: 100%;
    height: 100%;
    background: linear-gradient(rgba(255, 255, 255, 0.2), transparent);
    top: -100%;
    left: 0;
    transition: top var(--transition-normal);
}

.button:hover {
    transform: translateY(-2px);
    background-color: var(--accent-color);
}

.button:hover::after {
    top: 0;
}

.secondary-button {
    background-color: var(--secondary-button-color);
    color: var(--text-color);
}

.secondary-button:hover {
    background-color: #818CF8;
}

/* Feature List Styles */
.feature-list {
    list-style-type: none;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.feature-list li {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.feature-list li i {
    color: var(--success-color);
    font-size: 1.1rem;
}

/* QR Code Styles */
.qr-code {
    max-width: 200px;
    width: 100%;
    height: auto;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-sm);
    margin: var(--spacing-md) auto;
    transition: transform var(--transition-normal);
}

.qr-code:hover {
    transform: scale(1.05);
}

/* Message & Toast Styles */
.message {
    display: none;
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background-color: var(--card-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    padding: var(--spacing-lg);
    width: min(90%, 350px);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    transition: all var(--transition-normal);
    z-index: 1000;
}

.toast {
    position: fixed;
    bottom: var(--spacing-lg);
    right: var(--spacing-lg);
    background-color: var(--card-bg);
    color: var(--text-color);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    opacity: 0;
    transform: translateY(50px);
    transition: all var(--transition-normal);
}

.toast.show {
    opacity: 1;
    transform: translateY(0);
}

/* Progress Bar Styles */
.progress-bar {
    width: 100%;
    height: 4px;
    background-color: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-full);
    overflow: hidden;
    margin-top: var(--spacing-sm);
}

.progress {
    height: 100%;
    background-color: var(--accent-color);
    width: 0;
    transition: width var(--transition-normal);
}

/* Footer Styles */
footer {
    background-color: rgba(30, 41, 59, 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    padding: var(--spacing-lg);
    text-align: center;
    font-size: 0.875rem;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

footer a {
    color: var(--accent-color);
    text-decoration: none;
    transition: color var(--transition-normal);
}

footer a:hover {
    color: var(--button-color);
}

/* Responsive Design */
@media (max-width: 768px) {
    html {
        font-size: 14px;
    }

    .container {
        padding: var(--spacing-md);
        gap: var(--spacing-lg);
    }

    .card {
        padding: var(--spacing-md);
    }

    .message {
        width: 90%;
        padding: var(--spacing-md);
    }

    .toast {
        bottom: var(--spacing-md);
        right: var(--spacing-md);
        width: calc(100% - var(--spacing-md) * 2);
    }
}

@media (max-width: 480px) {
    .logo {
        font-size: 1.2rem;
    }

    .back-button {
        padding: var(--spacing-xs) var(--spacing-sm);
    }

    .version-box {
        width: 100%;
        justify-content: center;
    }

    .button {
        height: 2.75rem;
    }

    footer {
        padding: var(--spacing-md);
    }
}

/* Accessibility & Print */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

@media print {
    .button, .back-button {
        display: none;
    }

    body {
        background: white;
        color: black;
    }

    .card {
        break-inside: avoid;
        box-shadow: none;
        border: 1px solid #ddd;
    }
}