/* DIY Air Purifier Website - Global Styles */
:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --secondary-color: #10b981;
    --accent-color: #f59e0b;
    --text-color: #1f2937;
    --text-light: #6b7280;
    --bg-color: #ffffff;
    --bg-gray: #f3f4f6;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
}

* {
    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-color);
    background-color: var(--bg-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header & Navigation */
header {
    background-color: var(--bg-color);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

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

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
    flex-wrap: wrap;
}

.nav-links a {
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: var(--primary-color);
}

.promo-btn {
    background-color: var(--accent-color);
    color: white;
    padding: 0.5rem 1.5rem;
    border-radius: 5px;
    font-weight: 600;
    text-decoration: none;
    transition: background-color 0.3s;
}

.promo-btn:hover {
    background-color: #d97706;
}

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

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.hero p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 2rem;
    border-radius: 5px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s;
    border: none;
    cursor: pointer;
}

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

.btn-primary:hover {
    background-color: #059669;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(16,185,129,0.4);
}

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

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

/* Content Sections */
section {
    padding: 4rem 0;
}

h2 {
    font-size: 2rem;
    margin-bottom: 1.5rem;
    color: var(--text-color);
}

h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-color);
}

/* Grid Layouts */
.grid {
    display: grid;
    gap: 2rem;
}

.grid-2 {
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.grid-3 {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

/* Cards */
.card {
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
}

.keyword-card, .tech-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    transition: all 0.3s;
}

.keyword-card:hover, .tech-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 20px rgba(0,0,0,0.1);
}

.category-badge {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

/* Keywords & Technical Grids */
.keywords-grid, .technical-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

/* Benefits List */
.benefits {
    list-style: none;
    padding: 0;
}

.benefits li {
    padding: 0.5rem 0;
    padding-left: 2rem;
    position: relative;
}

.benefits li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
    font-weight: bold;
    font-size: 1.2rem;
}

/* Promo Codes */
.promo-code {
    background: linear-gradient(135deg, var(--accent-color), #d97706);
    color: white;
    padding: 1.5rem;
    border-radius: 8px;
    text-align: center;
    margin: 1rem 0;
}

.promo-code code {
    background: rgba(255,255,255,0.2);
    padding: 0.5rem 1rem;
    border-radius: 5px;
    font-size: 1.5rem;
    font-weight: bold;
    display: inline-block;
    margin: 0.5rem 0;
}

/* Reviews */
.review {
    background: var(--bg-gray);
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
}

.review-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.rating {
    color: var(--accent-color);
}

/* Certifications */
.cert-badge {
    background: white;
    border: 2px solid var(--secondary-color);
    border-radius: 8px;
    padding: 2rem;
    text-align: center;
}

.cert-badge img {
    max-width: 150px;
    margin-bottom: 1rem;
}

/* Footer */
footer {
    background-color: var(--text-color);
    color: white;
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h4 {
    margin-bottom: 1rem;
}

.footer-section ul {
    list-style: none;
}

.footer-section a {
    color: rgba(255,255,255,0.8);
    text-decoration: none;
    transition: color 0.3s;
}

.footer-section a:hover {
    color: white;
}

.copyright {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255,255,255,0.1);
    opacity: 0.7;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2rem;
    }
    
    .nav-links {
        gap: 1rem;
    }
    
    .keywords-grid, .technical-grid {
        grid-template-columns: 1fr;
    }
    
    h2 {
        font-size: 1.75rem;
    }
}

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

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

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

/* Video Embed Styling */
.review-video {
    margin: 2rem 0;
}

.video-embed {
    position: relative;
    padding-bottom: 56.25%; /* 16:9 aspect ratio */
    height: 0;
    overflow: hidden;
    max-width: 100%;
    background: #000;
    border-radius: 8px;
    margin: 1rem 0;
}

.video-embed iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.video-caption {
    text-align: center;
    margin-top: 0.5rem;
    font-size: 0.9rem;
}

.video-caption a {
    color: var(--primary-color);
    text-decoration: none;
}

.video-caption a:hover {
    text-decoration: underline;
}