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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: #424242;
    background-color: #ffffff;
}

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

/* Color Variables */
:root {
    --primary-green: #2E7D32;
    --secondary-blue: #1976D2;
    --accent-orange: #FF8F00;
    --light-gray: #F5F5F5;
    --dark-gray: #424242;
    --white: #FFFFFF;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
}

/* Header and Navigation */
.header {
    background: var(--white);
    box-shadow: var(--shadow);
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.nav-brand {
    display: flex;
    align-items: center;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-green);
}

.nav-brand i {
    margin-right: 0.5rem;
    font-size: 1.8rem;
}

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

.nav-link {
    text-decoration: none;
    color: var(--dark-gray);
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-link:hover {
    color: var(--primary-green);
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--dark-gray);
    cursor: pointer;
}

/* Hero Section */
.hero {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    padding: 8rem 2rem 4rem;
    max-width: 1200px;
    margin: 0 auto;
    min-height: 80vh;
}

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

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    color: var(--dark-gray);
    margin-bottom: 1.5rem;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.2rem;
    color: #666;
    margin-bottom: 2rem;
}

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

.hero-image img {
    width: 100%;
    height: auto;
    border-radius: 12px;
    box-shadow: var(--shadow-lg);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 2rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
    justify-content: center;
}

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

.btn-primary:hover {
    background: #1B5E20;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

.btn-secondary:hover {
    background: #1565C0;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-accent {
    background: var(--accent-orange);
    color: var(--white);
}

.btn-accent:hover {
    background: #F57C00;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* Section Styles */
.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    color: var(--dark-gray);
    margin-bottom: 3rem;
}

/* Systems Overview */
.systems-overview {
    padding: 4rem 0;
    background: var(--light-gray);
}

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

.system-card {
    background: var(--white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.system-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.system-icon {
    font-size: 3rem;
    color: var(--primary-green);
    margin-bottom: 1rem;
}

.system-card h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--dark-gray);
    margin-bottom: 1rem;
}

.system-card p {
    color: #666;
    margin-bottom: 1.5rem;
}

.system-benefits {
    list-style: none;
}

.system-benefits li {
    padding: 0.5rem 0;
    color: #666;
    position: relative;
    padding-left: 1.5rem;
}

.system-benefits li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--primary-green);
    font-weight: bold;
}

/* Calculator Sections */
.calculator-section {
    padding: 4rem 0;
}

.calculator-section:nth-child(even) {
    background: var(--light-gray);
}

.calculator-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: start;
}

.calculator-inputs {
    background: var(--white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.input-group {
    margin-bottom: 1.5rem;
}

.input-group label {
    display: block;
    font-weight: 600;
    color: var(--dark-gray);
    margin-bottom: 0.5rem;
}

.input-group input,
.input-group select {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid #E0E0E0;
    border-radius: 6px;
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

.input-group input:focus,
.input-group select:focus {
    outline: none;
    border-color: var(--primary-green);
}

.input-group small {
    display: block;
    color: #666;
    font-size: 0.875rem;
    margin-top: 0.25rem;
}

/* Results Container */
.results-container {
    background: var(--white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    min-height: 400px;
}

.results-container h3 {
    color: var(--dark-gray);
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
    border-bottom: 1px solid #E0E0E0;
}

.result-item:last-child {
    border-bottom: none;
}

.result-label {
    font-weight: 600;
    color: var(--dark-gray);
}

.result-value {
    font-weight: 700;
    font-size: 1.1rem;
}

.result-positive {
    color: var(--primary-green);
}

.result-negative {
    color: #D32F2F;
}

.result-neutral {
    color: var(--secondary-blue);
}

/* Comparison Section */
.comparison-section {
    padding: 4rem 0;
    background: var(--light-gray);
}

.comparison-container {
    background: var(--white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.comparison-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
}

.comparison-table th,
.comparison-table td {
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid #E0E0E0;
}

.comparison-table th {
    background: var(--light-gray);
    font-weight: 600;
    color: var(--dark-gray);
}

/* Footer */
.footer {
    background: var(--dark-gray);
    color: var(--white);
    padding: 3rem 0 1rem;
}

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

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1rem;
    color: var(--white);
}

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

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section ul li a {
    color: #CCCCCC;
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-section ul li a:hover {
    color: var(--white);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #555;
    color: #CCCCCC;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .nav-toggle {
        display: block;
    }
    
    .hero {
        grid-template-columns: 1fr;
        text-align: center;
        padding: 6rem 1rem 2rem;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .calculator-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .systems-grid {
        grid-template-columns: 1fr;
    }
    
    .container {
        padding: 0 1rem;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.75rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .btn {
        padding: 0.75rem 1.5rem;
        font-size: 0.9rem;
    }
}

/* Smooth Scrolling */
html {
    scroll-behavior: smooth;
}

/* Loading Animation */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid #f3f3f3;
    border-top: 3px solid var(--primary-green);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Chart Styles */
.chart-container {
    margin: 2rem 0;
    padding: 1rem;
    background: var(--light-gray);
    border-radius: 8px;
}

.savings-chart {
    width: 100%;
    height: 200px;
    background: linear-gradient(90deg, var(--primary-green) 0%, var(--secondary-blue) 100%);
    border-radius: 4px;
    position: relative;
    margin: 1rem 0;
}

.chart-label {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: var(--white);
    font-weight: 600;
    font-size: 1.1rem;
}