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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #fff;
}

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

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    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;
    color: #ababab;
}

/* Header */
.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.1);
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.8rem;
    margin: 0;
    font-weight: 700;
}

.nav {
    display: flex;
    gap: 2rem;
}

.nav-link {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
    padding: 0.5rem 1rem;
    border-radius: 25px;
    transition: all 0.3s ease;
}

.nav-link:hover {
    background: rgba(255, 255, 255, 0.2);
    color: white;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 100px 0;
    text-align: center;
}

.hero-title {
    font-size: 3rem;
    margin-bottom: 1.5rem;
    font-weight: 700;
}

.hero-subtitle {
    font-size: 1.2rem;
    opacity: 1;
    max-width: 600px;
    margin: 0 auto;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
    font-weight: 500;
}

/* Ad Banner */
.ad-banner {
    background: #f8f9fa;
    padding: 20px;
    text-align: center;
}

.ad-placeholder {
    background: #e9ecef;
    padding: 40px;
    border-radius: 8px;
    color: #6c757d;
    font-weight: 500;
    font-size: 1.1rem;
}

/* Sections */
.section {
    padding: 80px 0;
}

.section:nth-child(even) {
    background: #f8f9fa;
}

.section-title {
    text-align: center;
    margin-bottom: 3rem;
    font-size: 2.5rem;
    color: #333;
}

/* Content Grid */
.content-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(370px, 1fr));
    gap: 2rem;
}

.content-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease;
}

.content-card:hover {
    transform: translateY(-5px);
}

.content-card h3 {
    color: #667eea;
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.content-card ul {
    list-style: none;
    padding-left: 0;
}

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

.content-card li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: #667eea;
    font-weight: bold;
}

/* Calculator Section */
.calculator-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: start;
}

.calculator-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

.calculator-card h3 {
    color: #333;
    margin-bottom: 1rem;
    text-align: center;
}

.calculator-form {
    margin-bottom: 2rem;
}

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

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: #333;
}

.form-group input {
    width: 100%;
    padding: 12px;
    border: 2px solid #e9ecef;
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

.form-group input:focus {
    outline: none;
    border-color: #667eea;
}

.btn {
    width: 100%;
    padding: 12px 24px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: transform 0.3s ease;
}

.btn:hover {
    transform: translateY(-2px);
}

.calculator-result {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    text-align: center;
    border: 2px solid #e9ecef;
}

.result-value {
    font-size: 2rem;
    font-weight: 700;
    color: #667eea;
    margin-bottom: 0.5rem;
}

.result-category {
    font-size: 1.1rem;
    font-weight: 600;
    color: #333;
    margin-bottom: 0.5rem;
}

.result-description {
    color: #666;
    font-size: 0.9rem;
}

.bmi-info {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

.bmi-info h4 {
    color: #333;
    margin-bottom: 1rem;
}

.bmi-info ul {
    list-style: none;
    padding: 0;
}

.bmi-info li {
    padding: 0.5rem 0;
    border-bottom: 1px solid #eee;
    display: flex;
    justify-content: space-between;
}

.bmi-range {
    font-weight: 600;
    color: #667eea;
}

/* Tips Section */
.tips-section {
    background: #f8f9fa;
}

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

.tip-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease;
}

.tip-card:hover {
    transform: translateY(-5px);
}

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

.tip-card h3 {
    color: #333;
    margin-bottom: 1rem;
}

/* Footer */
.footer {
    background: #333;
    color: white;
    padding: 60px 0 20px;
}

.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: white;
}

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

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

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

.footer-section a:hover {
    color: #667eea;
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .header .container {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav {
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .content-grid {
        grid-template-columns: 1fr;
    }
    
    .calculator-container {
        grid-template-columns: 1fr;
    }
    
    .tips-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero {
        padding: 60px 0;
    }
    
    .section {
        padding: 60px 0;
    }
    
    .content-card,
    .calculator-card,
    .tip-card {
        padding: 1.5rem;
    }
}

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

.content-card,
.tip-card {
    animation: fadeInUp 0.6s ease-out;
}

/* Accessibility */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Focus styles */
.btn:focus,
.nav-link:focus,
input:focus {
    outline: 2px solid #667eea;
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    .btn {
        background: #000;
        color: #fff;
    }
    
    .nav-link:hover {
        background: #000;
        color: #fff;
    }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    html {
        scroll-behavior: auto;
    }
}