/* CSS Reset and Variables */
:root {
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --secondary-color: #64748b;
    --background-color: #ffffff;
    --surface-color: #f8fafc;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    --border-radius: 8px;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--background-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-sm);
}

/* Header Styles */
header {
    background: var(--background-color);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

nav {
    padding: var(--spacing-sm) 0;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-weight: 600;
    font-size: 1.25rem;
    color: var(--primary-color);
}

.nav-brand i {
    width: 24px;
    height: 24px;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--surface-color) 0%, var(--background-color) 100%);
    padding: var(--spacing-xl) 0;
    text-align: center;
    min-height: 60vh;
    display: flex;
    align-items: center;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: fadeInUp 0.8s ease-out;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
    animation: fadeInUp 0.8s ease-out 0.2s both;
}

/* Button Styles */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: 12px 24px;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: none;
    animation: fadeInUp 0.8s ease-out 0.4s both;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn i {
    width: 18px;
    height: 18px;
}

/* Features Section */
.features {
    padding: var(--spacing-xl) 0;
    background: var(--surface-color);
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.feature-card {
    background: var(--background-color);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.feature-card i {
    width: 48px;
    height: 48px;
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
}

.feature-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.feature-card p {
    color: var(--text-secondary);
}

/* Footer */
footer {
    background: var(--text-primary);
    color: white;
    text-align: center;
    padding: var(--spacing-lg) 0;
}

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

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

.pulse {
    animation: pulse 0.6s ease-in-out;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .feature-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }
    
    .container {
        padding: 0 var(--spacing-sm);
    }
}

@media (max-width: 480px) {
    .hero {
        padding: var(--spacing-lg) 0;
    }
    
    .hero-title {
        font-size: 1.75rem;
    }
}

/* Print Styles */
@media print {
    @page {
        margin: 1in;
        @top-center {
            content: "Hello World - Simple Webpage";
        }
        @bottom-center {
            content: "Created by Helium";
        }
    }
    
    header, footer {
        display: none;
    }
    
    .hero {
        page-break-inside: avoid;
    }
    
    .feature-card {
        page-break-inside: avoid;
        box-shadow: none;
        border: 1px solid #ccc;
    }
}