/* ========================================
   Convert KG to LBS - Main Stylesheet
   Fully Responsive + AI/SEO Optimized
   ======================================== */

:root {
    --primary: #2563eb;
    --primary-dark: #1e40af;
    --text: #1f2937;
    --text-light: #64748b;
    --bg: #f8fafc;
    --white: #ffffff;
    --border: #e2e8f0;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    line-height: 1.75;
    color: var(--text);
    background: var(--bg);
    font-size: 16px;
}

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

/* Header & Navigation */
header {
    background: var(--white);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
    position: sticky;
    top: 0;
    z-index: 100;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

.logo {
    font-size: 1.85rem;
    font-weight: 800;
    color: var(--primary);
    text-decoration: none;
}

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

.nav-links a {
    color: #374151;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s ease;
}

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

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #2563eb 0%, #1e40af 100%);
    color: var(--white);
    padding: 5rem 0;
    text-align: center;
}

.hero h1 {
    font-size: 3.2rem;
    font-weight: 800;
    margin-bottom: 1rem;
    line-height: 1.15;
}

.hero-subtitle {
    font-size: 1.35rem;
    max-width: 720px;
    margin: 0 auto 2rem;
    opacity: 0.95;
}

/* Main Answer Box */
.main-answer {
    background: var(--white);
    border-radius: 20px;
    padding: 2.5rem;
    margin: 2rem auto;
    max-width: 720px;
    box-shadow: 0 20px 25px -5px rgb(0 0 0 / 0.1);
    text-align: center;
}

.answer-value {
    font-size: 4rem;
    font-weight: 800;
    color: var(--primary);
    line-height: 1;
}

/* Interactive Converter */
.converter-box {
    background: var(--white);
    padding: 2.5rem;
    border-radius: 20px;
    box-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    margin: 3rem 0;
}

.converter-input {
    display: flex;
    gap: 1rem;
    align-items: center;
    flex-wrap: wrap;
}

input[type="number"] {
    flex: 1;
    min-width: 160px;
    padding: 1.1rem;
    font-size: 1.3rem;
    border: 2px solid var(--border);
    border-radius: 14px;
    outline: none;
}

input[type="number"]:focus {
    border-color: var(--primary);
}

/* Buttons */
.btn {
    background: var(--primary);
    color: var(--white);
    padding: 1.1rem 2.4rem;
    border: none;
    border-radius: 14px;
    font-size: 1.1rem;
    font-weight: 700;
    cursor: pointer;
    text-decoration: none;
    display: inline-block;
    transition: all 0.2s ease;
}

.btn:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
}

/* Sections */
section {
    margin: 4.5rem 0;
}

h2 {
    font-size: 2.35rem;
    margin-bottom: 1.5rem;
    color: #1e2937;
    font-weight: 700;
}

h3 {
    font-size: 1.65rem;
    margin: 2rem 0 1rem;
    color: #334155;
}

/* FAQ */
.faq-item {
    background: var(--white);
    padding: 1.6rem;
    border-radius: 14px;
    margin-bottom: 1rem;
    box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1);
}

.faq-question {
    font-weight: 700;
    font-size: 1.15rem;
    margin-bottom: 0.6rem;
    color: #1e2937;
}

/* Internal Links */
.internal-links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.7rem;
}

.internal-links a {
    background: #e0f2fe;
    color: #0369a1;
    padding: 0.55rem 1.1rem;
    border-radius: 9999px;
    text-decoration: none;
    font-size: 0.95rem;
    transition: all 0.2s;
}

.internal-links a:hover {
    background: #bae6fd;
}

/* Footer */
footer {
    background: #0f172a;
    color: #94a3b8;
    padding: 3.5rem 0;
    margin-top: 4rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.4rem;
    }
    
    .answer-value {
        font-size: 3.2rem;
    }
    
    .nav-links {
        display: none;
    }
    
    .converter-input {
        flex-direction: column;
        align-items: stretch;
    }
    
    input[type="number"] {
        width: 100%;
    }
    
    h2 {
        font-size: 1.9rem;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 3.5rem 0;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
}