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

:root {
    --color-navy: #0D1B2A;
    --color-slate: #1B263B;
    --color-blue: #415A77;
    --color-gray: #778DA9;
    --color-bone: #E0E1DD;
    --color-white: #FFFFFF;
    --color-success: #10B981;
    --color-warning: #F59E0B;
    --color-error: #EF4444;
    
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --border-radius: 8px;
    --border-radius-lg: 16px;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --transition: all 0.2s ease-in-out;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--color-navy);
    background-color: var(--color-bone);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1rem;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

p {
    margin-bottom: 1rem;
}

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

a:hover {
    color: var(--color-slate);
}

/* Header */
.header {
    background-color: var(--color-white);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav {
    padding: 1rem 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--color-navy);
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-link {
    font-weight: 500;
    color: var(--color-slate);
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.nav-link:hover {
    background-color: var(--color-bone);
    color: var(--color-navy);
}

.nav-link-primary {
    background-color: var(--color-blue);
    color: var(--color-white);
}

.nav-link-primary:hover {
    background-color: var(--color-slate);
    color: var(--color-white);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    font-weight: 600;
    border-radius: var(--border-radius);
    border: none;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
    font-size: 1rem;
    line-height: 1;
}

.btn-primary {
    background-color: var(--color-blue);
    color: var(--color-white);
}

.btn-primary:hover {
    background-color: var(--color-slate);
    color: var(--color-white);
}

.btn-secondary {
    background-color: var(--color-gray);
    color: var(--color-white);
}

.btn-secondary:hover {
    background-color: var(--color-slate);
    color: var(--color-white);
}

.btn-outline {
    background-color: transparent;
    color: var(--color-blue);
    border: 2px solid var(--color-blue);
}

.btn-outline:hover {
    background-color: var(--color-blue);
    color: var(--color-white);
}

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.125rem;
}

/* Main Content */
.main {
    flex: 1;
}

/* Hero Section */
.hero {
    padding: 4rem 0;
    background: linear-gradient(135deg, var(--color-white) 0%, var(--color-bone) 100%);
}

.hero-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-content {
    max-width: 500px;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    color: var(--color-navy);
    margin-bottom: 1.5rem;
    line-height: 1.1;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--color-slate);
    margin-bottom: 2rem;
    line-height: 1.5;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.game-preview {
    width: 280px;
    height: 400px;
    background: linear-gradient(180deg, #87CEEB 0%, #98D8E8 100%);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.preview-sky {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 70%;
    background: linear-gradient(180deg, #87CEEB 0%, #98D8E8 100%);
}

.preview-bird {
    position: absolute;
    top: 40%;
    left: 20%;
    width: 40px;
    height: 30px;
    background-color: var(--color-warning);
    border-radius: 50% 50% 50% 50% / 60% 60% 40% 40%;
    animation: float 2s ease-in-out infinite;
}

.preview-bird::before {
    content: '';
    position: absolute;
    top: 8px;
    right: 5px;
    width: 8px;
    height: 8px;
    background-color: var(--color-navy);
    border-radius: 50%;
}

.preview-pipes {
    position: absolute;
    bottom: 0;
    right: 15%;
    display: flex;
    flex-direction: column;
    gap: 100px;
}

.preview-pipe {
    width: 60px;
    height: 120px;
    background-color: var(--color-success);
    border-radius: 4px;
}

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

/* Features Section */
.features {
    padding: 4rem 0;
    background-color: var(--color-white);
}

.features-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.features-title {
    text-align: center;
    color: var(--color-navy);
    margin-bottom: 3rem;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.feature-card {
    background-color: var(--color-bone);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    text-align: center;
    transition: var(--transition);
}

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

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    color: var(--color-navy);
    margin-bottom: 1rem;
}

.feature-card p {
    color: var(--color-slate);
    margin-bottom: 0;
}

/* Footer */
.footer {
    background-color: var(--color-navy);
    color: var(--color-bone);
    padding: 2rem 0;
    margin-top: auto;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.footer-links a {
    color: var(--color-gray);
    font-weight: 500;
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--color-bone);
}

.footer-attribution {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1rem;
    font-size: 0.875rem;
    color: var(--color-gray);
    text-align: center;
    flex-wrap: wrap;
}

.footer-contact {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 2rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--color-gray);
    transition: var(--transition);
    font-size: 0.875rem;
}

.contact-item:hover {
    color: var(--color-bone);
}

.contact-item svg {
    width: 16px;
    height: 16px;
}

.github-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--color-gray);
    transition: var(--transition);
}

.github-link:hover {
    color: var(--color-bone);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-container {
        padding: 0 1rem;
    }
    
    .nav-links {
        gap: 1rem;
    }
    
    .nav-link {
        padding: 0.5rem 0.75rem;
        font-size: 0.875rem;
    }
    
    .hero-container {
        grid-template-columns: 1fr;
        gap: 2rem;
        text-align: center;
        padding: 0 1rem;
    }
    
    .hero-title {
        font-size: 2.5rem;
        line-height: 1.2;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
        margin-bottom: 1.5rem;
    }
    
    .game-preview {
        width: 240px;
        height: 340px;
    }
    
    .features {
        padding: 3rem 0;
    }
    
    .features-container {
        padding: 0 1rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .feature-card {
        padding: 1.5rem;
    }
    
    .footer-links {
        gap: 1rem;
        font-size: 0.875rem;
    }
    
    .footer-contact {
        gap: 1rem;
    }
    
    .contact-item {
        font-size: 0.75rem;
    }
    
    .footer-attribution {
        flex-direction: column;
        gap: 0.5rem;
        font-size: 0.75rem;
    }
}

@media (max-width: 480px) {
    .nav-container {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
    }
    
    .nav-links {
        justify-content: center;
        flex-wrap: wrap;
    }
    
    .hero {
        padding: 2rem 0;
    }
    
    .hero-title {
        font-size: 2rem;
        margin-bottom: 1rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
        margin-bottom: 1.5rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        gap: 0.75rem;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
        padding: 1rem;
    }
    
    .game-preview {
        width: 200px;
        height: 300px;
    }
    
    .features-title {
        font-size: 1.75rem;
        margin-bottom: 2rem;
    }
    
    .feature-card {
        padding: 1.25rem;
    }
    
    .feature-card h3 {
        font-size: 1.125rem;
    }
    
    .footer {
        padding: 1.5rem 0;
    }
    
    .footer-container {
        padding: 0 1rem;
    }
    
    .footer-links {
        flex-direction: column;
        gap: 0.75rem;
        text-align: center;
    }
    
    .footer-contact {
        flex-direction: column;
        gap: 0.75rem;
        text-align: center;
    }
}

/* Utility Classes */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.hidden { display: none; }
.visible { display: block; }