/* ===== CSS Variables ===== */
:root {
    --primary: #FF6B35;
    --primary-dark: #E5562A;
    --secondary: #1E3A5F;
    --secondary-light: #2D4A6F;
    --accent: #FFB800;
    --success: #10B981;
    --danger: #EF4444;
    --warning: #F59E0B;
    --text: #1F2937;
    --text-light: #6B7280;
    --text-lighter: #9CA3AF;
    --bg: #FFFFFF;
    --bg-alt: #F9FAFB;
    --bg-dark: #F3F4F6;
    --border: #E5E7EB;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow: 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);
    --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 10px 10px -5px rgba(0,0,0,0.04);
    --radius: 12px;
    --radius-lg: 16px;
    --transition: all 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text);
    background: var(--bg);
    -webkit-font-smoothing: antialiased;
}

img {
    max-width: 100%;
    height: auto;
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

/* ===== Container ===== */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 28px;
    font-size: 16px;
    font-weight: 600;
    border-radius: var(--radius);
    border: none;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: white;
    box-shadow: 0 4px 14px rgba(255, 107, 53, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(255, 107, 53, 0.5);
}

.btn-secondary {
    background: var(--bg);
    color: var(--secondary);
    border: 2px solid var(--border);
}

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

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

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

/* ===== Header ===== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 72px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 24px;
    font-weight: 700;
}

.logo-icon {
    font-size: 28px;
}

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

.logo-au {
    color: var(--primary);
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 32px;
}

.nav-links a {
    font-weight: 500;
    color: var(--text-light);
    transition: var(--transition);
}

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

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.mobile-menu-btn span {
    width: 24px;
    height: 2px;
    background: var(--secondary);
    transition: var(--transition);
}

/* ===== Hero Section ===== */
.hero {
    position: relative;
    padding: 160px 0 100px;
    background: linear-gradient(135deg, #FFF7ED 0%, #FEF3C7 50%, #DBEAFE 100%);
    overflow: hidden;
}

.hero-gradient {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 100px;
    background: linear-gradient(to bottom, transparent, var(--bg));
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 56px;
    font-weight: 800;
    line-height: 1.1;
    color: var(--secondary);
    margin-bottom: 24px;
}

.hero-subtitle {
    font-size: 20px;
    color: var(--text-light);
    margin-bottom: 32px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-cta {
    display: flex;
    gap: 16px;
    justify-content: center;
    margin-bottom: 60px;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 48px;
}

.stat {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 36px;
    font-weight: 800;
    color: var(--primary);
}

.stat-label {
    font-size: 14px;
    color: var(--text-light);
}

/* ===== Section Styles ===== */
.section-title {
    font-size: 40px;
    font-weight: 800;
    color: var(--secondary);
    text-align: center;
    margin-bottom: 12px;
}

.section-subtitle {
    font-size: 18px;
    color: var(--text-light);
    text-align: center;
    margin-bottom: 48px;
}

/* ===== Benefits Section ===== */
.benefits {
    padding: 100px 0;
    background: var(--bg);
}

.benefits-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.benefit-card {
    padding: 32px;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    transition: var(--transition);
}

.benefit-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.benefit-icon {
    font-size: 40px;
    margin-bottom: 16px;
}

.benefit-card h3 {
    font-size: 20px;
    font-weight: 700;
    color: var(--secondary);
    margin-bottom: 12px;
}

.benefit-card p {
    color: var(--text-light);
    font-size: 15px;
}

/* ===== Products Section ===== */
.products {
    padding: 100px 0;
    background: var(--bg-alt);
}

.product-filters {
    display: flex;
    justify-content: center;
    gap: 12px;
    margin-bottom: 48px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 10px 24px;
    font-size: 14px;
    font-weight: 600;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 50px;
    cursor: pointer;
    transition: var(--transition);
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--secondary);
    color: white;
    border-color: var(--secondary);
}

.product-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    margin-bottom: 48px;
}

.product-card {
    position: relative;
    background: var(--bg);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.product-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
}

.product-card.hidden {
    display: none;
}

.product-badge {
    position: absolute;
    top: 16px;
    left: 16px;
    padding: 6px 12px;
    font-size: 12px;
    font-weight: 700;
    border-radius: 50px;
    z-index: 1;
    text-transform: uppercase;
}

.product-badge.bestseller {
    background: var(--primary);
    color: white;
}

.product-badge.popular {
    background: var(--accent);
    color: var(--secondary);
}

.product-badge.premium {
    background: var(--secondary);
    color: white;
}

.product-badge.value {
    background: var(--success);
    color: white;
}

.product-badge.new {
    background: #8B5CF6;
    color: white;
}

.product-badge.eco {
    background: #059669;
    color: white;
}

.product-image {
    aspect-ratio: 4/3;
    background: linear-gradient(135deg, #F3F4F6 0%, #E5E7EB 100%);
    display: flex;
    align-items: center;
    justify-content: center;
}

.product-placeholder {
    text-align: center;
}

.product-placeholder span {
    font-size: 48px;
    display: block;
    margin-bottom: 8px;
}

.product-placeholder small {
    font-size: 14px;
    color: var(--text-light);
}

.product-info {
    padding: 20px;
}

.product-rating {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 8px;
}

.stars {
    color: var(--accent);
    font-size: 14px;
}

.rating-count {
    font-size: 13px;
    color: var(--text-light);
}

.product-title {
    font-size: 16px;
    font-weight: 700;
    color: var(--secondary);
    margin-bottom: 8px;
    line-height: 1.3;
}

.product-desc {
    font-size: 14px;
    color: var(--text-light);
    margin-bottom: 12px;
    line-height: 1.5;
}

.product-features {
    margin-bottom: 16px;
}

.product-features li {
    font-size: 13px;
    color: var(--text);
    margin-bottom: 4px;
}

.product-price {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.price {
    font-size: 24px;
    font-weight: 800;
    color: var(--secondary);
}

.price-note {
    font-size: 13px;
    color: var(--success);
    font-weight: 500;
}

.product-btn {
    width: 100%;
    padding: 12px;
    font-size: 14px;
}

.products-cta {
    text-align: center;
}

/* ===== Guide Section ===== */
.guide {
    padding: 100px 0;
    background: var(--bg);
}

.guide-content {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
}

.guide-card {
    position: relative;
    padding: 32px;
    padding-left: 100px;
    background: var(--bg-alt);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
}

.guide-number {
    position: absolute;
    left: 24px;
    top: 24px;
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    font-weight: 800;
    color: white;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    border-radius: 50%;
}

.guide-card h3 {
    font-size: 20px;
    font-weight: 700;
    color: var(--secondary);
    margin-bottom: 12px;
}

.guide-card p {
    font-size: 15px;
    color: var(--text-light);
    line-height: 1.7;
}

/* ===== FAQ Section ===== */
.faq {
    padding: 100px 0;
    background: var(--bg-alt);
}

.faq-list {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    margin-bottom: 16px;
    background: var(--bg);
    border-radius: var(--radius);
    overflow: hidden;
    border: 1px solid var(--border);
}

.faq-question {
    width: 100%;
    padding: 20px 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 16px;
    font-weight: 600;
    color: var(--secondary);
    background: none;
    border: none;
    cursor: pointer;
    text-align: left;
    transition: var(--transition);
}

.faq-question:hover {
    background: var(--bg-alt);
}

.faq-icon {
    font-size: 24px;
    font-weight: 300;
    color: var(--primary);
    transition: var(--transition);
}

.faq-item.active .faq-icon {
    transform: rotate(45deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.faq-item.active .faq-answer {
    max-height: 500px;
}

.faq-answer p {
    padding: 0 24px 20px;
    font-size: 15px;
    color: var(--text-light);
    line-height: 1.7;
}

/* ===== Calculator Section ===== */
.calculator {
    padding: 100px 0;
    background: linear-gradient(135deg, var(--secondary) 0%, var(--secondary-light) 100%);
}

.calculator .section-title,
.calculator .section-subtitle {
    color: white;
}

.calculator .section-subtitle {
    opacity: 0.8;
}

.calculator-wrapper {
    max-width: 900px;
    margin: 0 auto;
}

.calculator-input {
    text-align: center;
    margin-bottom: 48px;
}

.calculator-input label {
    display: block;
    font-size: 18px;
    font-weight: 600;
    color: white;
    margin-bottom: 16px;
}

.temp-slider {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 24px;
}

.temp-slider input[type="range"] {
    width: 300px;
    height: 8px;
    -webkit-appearance: none;
    appearance: none;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 4px;
    outline: none;
}

.temp-slider input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 24px;
    height: 24px;
    background: var(--primary);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

.temp-display {
    font-size: 32px;
    font-weight: 800;
    color: white;
    min-width: 100px;
}

.calculator-results {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.result-card {
    padding: 32px;
    background: white;
    border-radius: var(--radius-lg);
    text-align: center;
}

.result-label {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-light);
    margin-bottom: 8px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.result-temp {
    font-size: 48px;
    font-weight: 800;
    margin-bottom: 8px;
}

.result-card.danger .result-temp {
    color: var(--danger);
}

.result-card.safe .result-temp {
    color: var(--success);
}

.result-card.savings .result-temp {
    color: var(--primary);
}

.result-desc {
    font-size: 14px;
    color: var(--text-light);
}

/* ===== SEO Content Section ===== */
.seo-content {
    padding: 80px 0;
    background: var(--bg-alt);
    border-top: 1px solid var(--border);
}

.seo-content h2 {
    font-size: 32px;
    font-weight: 800;
    color: var(--secondary);
    margin-bottom: 24px;
}

.seo-text {
    max-width: 900px;
}

.seo-text h3 {
    font-size: 20px;
    font-weight: 700;
    color: var(--secondary);
    margin-top: 32px;
    margin-bottom: 12px;
}

.seo-text p {
    font-size: 15px;
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: 16px;
}

.seo-text strong {
    color: var(--text);
}

/* ===== Footer ===== */
.footer {
    padding: 80px 0 40px;
    background: var(--secondary);
    color: white;
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 48px;
    margin-bottom: 48px;
}

.footer-brand p {
    margin-top: 16px;
    font-size: 14px;
    opacity: 0.8;
    line-height: 1.7;
}

.footer-brand .logo-text {
    color: white;
}

.footer-links h4 {
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 20px;
}

.footer-links ul li {
    margin-bottom: 12px;
}

.footer-links a {
    font-size: 14px;
    opacity: 0.8;
    transition: var(--transition);
}

.footer-links a:hover {
    opacity: 1;
    color: var(--primary);
}

.footer-bottom {
    padding-top: 32px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
}

.footer-bottom p {
    font-size: 14px;
    opacity: 0.7;
    margin-bottom: 8px;
}

.affiliate-notice {
    font-size: 12px;
    opacity: 0.5;
}

/* ===== Responsive Design ===== */
@media (max-width: 1024px) {
    .product-grid {
        grid-template-columns: repeat(3, 1fr);
    }

    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: 72px;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 24px;
        gap: 16px;
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow-lg);
    }

    .nav-links.active {
        display: flex;
    }

    .mobile-menu-btn {
        display: flex;
    }

    .hero {
        padding: 120px 0 80px;
    }

    .hero h1 {
        font-size: 36px;
    }

    .hero-subtitle {
        font-size: 16px;
    }

    .hero-cta {
        flex-direction: column;
        gap: 12px;
    }

    .hero-stats {
        flex-direction: column;
        gap: 24px;
    }

    .section-title {
        font-size: 28px;
    }

    .benefits-grid {
        grid-template-columns: 1fr;
    }

    .product-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 16px;
    }

    .guide-content {
        grid-template-columns: 1fr;
    }

    .guide-card {
        padding-left: 32px;
        padding-top: 80px;
    }

    .guide-number {
        left: 32px;
        top: 24px;
    }

    .calculator-results {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .temp-slider {
        flex-direction: column;
        gap: 16px;
    }

    .temp-slider input[type="range"] {
        width: 100%;
        max-width: 300px;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 32px;
    }
}

@media (max-width: 480px) {
    .product-grid {
        grid-template-columns: 1fr;
    }

    .product-filters {
        gap: 8px;
    }

    .filter-btn {
        padding: 8px 16px;
        font-size: 13px;
    }

    .hero h1 {
        font-size: 28px;
    }

    .section-title {
        font-size: 24px;
    }

    .result-temp {
        font-size: 36px;
    }
}