/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Minimal color palette inspired by the logo */
    --primary: #4A90E2;
    --primary-light: #6BA3E8;
    --accent: #F5A623;
    --success: #7ED321;
    --error: #D0021B;
    
    /* Neutral colors */
    --white: #FFFFFF;
    --gray-50: #FAFAFA;
    --gray-100: #F5F5F5;
    --gray-200: #EEEEEE;
    --gray-300: #E0E0E0;
    --gray-400: #BDBDBD;
    --gray-500: #9E9E9E;
    --gray-600: #757575;
    --gray-700: #616161;
    --gray-800: #424242;
    --gray-900: #212121;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 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;
    
    /* Spacing */
    --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;
    
    /* Border radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
    --shadow-md: 0 3px 6px rgba(0, 0, 0, 0.16), 0 3px 6px rgba(0, 0, 0, 0.23);
    --shadow-lg: 0 10px 20px rgba(0, 0, 0, 0.19), 0 6px 6px rgba(0, 0, 0, 0.23);
    --shadow-xl: 0 14px 28px rgba(0, 0, 0, 0.25), 0 10px 10px rgba(0, 0, 0, 0.22);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--gray-800);
    background: var(--white);
    min-height: 100vh;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-4);
}

@media (min-width: 768px) {
    .container {
        padding: 0 var(--space-6);
    }
}

/* Header */
.header {
    background: var(--white);
    border-bottom: 1px solid var(--gray-200);
    padding: var(--space-8) 0;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
}

.logo-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-6);
}

.logo {
    width: 80px;
    height: 80px;
    object-fit: contain;
}

.brand {
    text-align: left;
}

.title {
    font-size: var(--font-size-3xl);
    font-weight: 300;
    color: var(--gray-900);
    margin-bottom: var(--space-1);
    letter-spacing: -0.025em;
}

.tagline {
    font-size: var(--font-size-sm);
    color: var(--gray-600);
    font-weight: 400;
    font-style: italic;
}

/* Main content */
.main {
    padding: var(--space-16) 0;
    min-height: calc(100vh - 200px);
}

/* Stacks Container */
.stacks-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-8);
    max-width: 600px;
    margin: 0 auto;
}

/* Stack Items */
.stack-item {
    width: 100%;
    max-width: 400px;
    position: relative;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.stack-item:hover {
    transform: translateY(-4px);
}

.stack-item:active {
    transform: translateY(-2px);
}

.stack-content {
    background: var(--white);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-xl);
    padding: var(--space-8);
    text-align: center;
    position: relative;
    z-index: 2;
    transition: all var(--transition-normal);
}

.stack-item:hover .stack-content {
    border-color: var(--primary);
    box-shadow: var(--shadow-lg);
}

.stack-shadow {
    position: absolute;
    bottom: -8px;
    left: 8px;
    right: -8px;
    height: 8px;
    background: var(--gray-300);
    border-radius: var(--radius-xl);
    z-index: 1;
}

.stack-icon {
    font-size: var(--font-size-4xl);
    margin-bottom: var(--space-4);
    display: block;
    transition: transform var(--transition-fast);
}

.stack-item:hover .stack-icon {
    transform: scale(1.1);
}

.stack-content h2 {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: var(--space-2);
}

.stack-content p {
    color: var(--gray-600);
    font-size: var(--font-size-sm);
}

/* Stack Detail Views */
.stack-detail {
    max-width: 800px;
    margin: 0 auto;
    animation: slideIn var(--transition-normal) ease-out;
}

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

.detail-header {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    margin-bottom: var(--space-12);
    padding-bottom: var(--space-6);
    border-bottom: 1px solid var(--gray-200);
}

.back-btn {
    background: var(--gray-100);
    border: none;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: var(--font-size-lg);
    color: var(--gray-600);
}

.back-btn:hover {
    background: var(--gray-200);
    color: var(--gray-800);
}

.detail-header h2 {
    font-size: var(--font-size-3xl);
    font-weight: 600;
    color: var(--gray-900);
}

/* Activities Grid */
.activities-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--space-6);
}

.activity-item {
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: var(--space-6);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.activity-item:hover {
    background: var(--white);
    border-color: var(--primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.activity-icon {
    font-size: var(--font-size-3xl);
    margin-bottom: var(--space-3);
    display: block;
}

.activity-item h3 {
    font-size: var(--font-size-base);
    font-weight: 600;
    color: var(--gray-800);
}

/* Content Sections */
.content-sections {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-8);
}

.content-section {
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: var(--space-6);
}

.content-section h3 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--gray-800);
    margin-bottom: var(--space-4);
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.content-section ul {
    list-style: none;
    padding: 0;
}

.content-section li {
    padding: var(--space-2) 0;
    border-bottom: 1px solid var(--gray-200);
    color: var(--gray-700);
    font-size: var(--font-size-sm);
}

.content-section li:last-child {
    border-bottom: none;
}

.content-section strong {
    color: var(--gray-900);
    font-weight: 600;
}

/* Footer */
.footer {
    background: var(--gray-50);
    border-top: 1px solid var(--gray-200);
    padding: var(--space-8) 0;
    text-align: center;
}

.footer .tagline {
    font-size: var(--font-size-base);
    color: var(--gray-600);
    font-weight: 400;
    font-style: italic;
}

/* Responsive design */
@media (max-width: 768px) {
    .logo-container {
        flex-direction: column;
        gap: var(--space-4);
        text-align: center;
    }
    
    .logo {
        width: 60px;
        height: 60px;
    }
    
    .title {
        font-size: var(--font-size-2xl);
    }
    
    .stacks-container {
        gap: var(--space-6);
    }
    
    .stack-content {
        padding: var(--space-6);
    }
    
    .stack-icon {
        font-size: var(--font-size-3xl);
    }
    
    .stack-content h2 {
        font-size: var(--font-size-xl);
    }
    
    .activities-grid {
        grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
        gap: var(--space-4);
    }
    
    .activity-item {
        padding: var(--space-4);
    }
    
    .activity-icon {
        font-size: var(--font-size-2xl);
    }
    
    .content-sections {
        grid-template-columns: 1fr;
        gap: var(--space-6);
    }
    
    .detail-header h2 {
        font-size: var(--font-size-2xl);
    }
}

/* Accessibility improvements */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus styles for keyboard navigation */
.stack-item:focus-visible,
.back-btn:focus-visible,
.activity-item:focus-visible {
    outline: 3px solid var(--primary);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --primary: #0000ff;
        --gray-800: #000000;
        --gray-600: #333333;
    }
    
    .stack-content {
        border: 2px solid var(--gray-800);
    }
}

/* Haptic feedback support */
@media (hover: none) and (pointer: coarse) {
    .stack-item:active,
    .back-btn:active,
    .activity-item:active {
        transform: scale(0.98);
    }
}

/* Loading animation */
body:not(.loaded) {
    opacity: 0;
    transition: opacity 0.5s ease;
}

body.loaded {
    opacity: 1;
}

/* Stack reveal animation */
.stack-item {
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 0.6s ease forwards;
}

.stack-item:nth-child(1) { animation-delay: 0.1s; }
.stack-item:nth-child(2) { animation-delay: 0.2s; }
.stack-item:nth-child(3) { animation-delay: 0.3s; }
.stack-item:nth-child(4) { animation-delay: 0.4s; }

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