/* ============================================
   FLAMES Calculator - Modern Responsive Design
   Mobile-First Approach with SEO Optimization
   ============================================ */

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

:root {
    /* Colors */
    --primary-color: #ff3366;
    --secondary-color: #ff6b9d;
    --accent-color: #ffa7c4;
    --bg-gradient-1: #fff5f7;
    --bg-gradient-2: #ffe0e9;
    --text-dark: #2d3748;
    --text-light: #718096;
    --white: #ffffff;
    --border-color: #e2e8f0;
    --shadow: rgba(0, 0, 0, 0.1);
    --shadow-hover: rgba(0, 0, 0, 0.15);
    
    /* Spacing */
    --container-max-width: 1200px;
    --section-padding: 4rem 1rem;
    
    /* Typography */
    --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-size-base: 16px;
}

html {
    scroll-behavior: smooth;
    font-size: var(--font-size-base);
}

body {
    font-family: var(--font-primary);
    line-height: 1.6;
    color: var(--text-dark);
    background: linear-gradient(135deg, var(--bg-gradient-1) 0%, var(--bg-gradient-2) 100%);
    background-attachment: fixed;
    min-height: 100vh;
    overflow-x: hidden;
}

.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
    width: 100%;
}

/* ===== Header & Navigation ===== */
.header {
    background: var(--white);
    box-shadow: 0 2px 10px var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
    color: inherit;
    transition: opacity 0.3s ease;
}

.logo:hover {
    opacity: 0.8;
}

.logo-img {
    width: 40px;
    height: 40px;
    object-fit: contain;
}

.logo-text {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
    display: none;
}

.mobile-toggle {
    display: flex;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.mobile-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-dark);
    border-radius: 3px;
    transition: all 0.3s ease;
}

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

.nav-menu li a {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
}

.nav-menu li a:hover,
.nav-menu li a.active {
    color: var(--primary-color);
}

.nav-menu li a.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--primary-color);
}

/* Desktop Navigation */
@media (min-width: 768px) {
    .logo-text {
        display: block;
    }
    
    .mobile-toggle {
        display: none;
    }
    
    .nav-menu {
        display: flex;
    }
}

/* ===== Hero Section ===== */
.hero {
    padding: 3rem 0 2rem;
    text-align: center;
}

.hero-content {
    max-width: 700px;
    margin: 0 auto;
}

.hero-title {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--primary-color);
    margin-bottom: 1rem;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 0.75rem;
}

.hero-description {
    font-size: 1rem;
    color: var(--text-light);
    max-width: 600px;
    margin: 0 auto;
}

@media (min-width: 768px) {
    .hero {
        padding: 4rem 0 3rem;
    }
    
    .hero-title {
        font-size: 3.5rem;
    }
}

/* ===== Calculator Section ===== */
.calculator-section {
    padding: 2rem 0;
}

.calculator-card {
    background: var(--white);
    border-radius: 20px;
    padding: 2rem;
    box-shadow: 0 10px 40px var(--shadow);
    max-width: 600px;
    margin: 0 auto;
}

.card-header {
    text-align: center;
    margin-bottom: 2rem;
}

.card-header h2 {
    font-size: 1.75rem;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.card-header p {
    color: var(--text-light);
    font-size: 0.95rem;
}

.flames-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-weight: 600;
    color: var(--text-dark);
    font-size: 0.95rem;
}

.form-group input {
    padding: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 12px;
    font-size: 1rem;
    font-family: inherit;
    transition: all 0.3s ease;
    outline: none;
}

.form-group input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(255, 51, 102, 0.1);
}

.heart-divider {
    text-align: center;
    font-size: 2rem;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.1); }
}

.btn-calculate {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--white);
    padding: 1.1rem 2rem;
    border: none;
    border-radius: 12px;
    font-size: 1.1rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    box-shadow: 0 4px 15px rgba(255, 51, 102, 0.3);
}

.btn-calculate:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(255, 51, 102, 0.4);
}

.btn-calculate:active {
    transform: translateY(0);
}

.btn-icon {
    font-size: 1.3rem;
    transition: transform 0.3s ease;
}

.btn-calculate:hover .btn-icon {
    transform: translateX(5px);
}

/* ===== Result Display ===== */
.result-container {
    text-align: center;
    padding: 2rem 0;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

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

.result-emoji {
    font-size: 4rem;
    margin: 1rem 0;
    animation: bounce 1s ease;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-20px); }
}

.result-letter {
    font-size: 5rem;
    font-weight: 900;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin: 0.5rem 0;
}

.result-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 1rem;
}

.result-percentage {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
}

.result-description {
    font-size: 1.05rem;
    color: var(--text-light);
    line-height: 1.7;
    margin-bottom: 1.5rem;
    padding: 0 1rem;
}

.result-details {
    background: var(--bg-gradient-1);
    padding: 1.5rem;
    border-radius: 12px;
    margin: 1.5rem 0;
    text-align: left;
}

.result-details h4 {
    color: var(--primary-color);
    margin-bottom: 0.75rem;
    font-size: 1.1rem;
}

.result-details p {
    color: var(--text-dark);
    line-height: 1.6;
    margin-bottom: 0.5rem;
}

.btn-reset {
    background: var(--white);
    color: var(--primary-color);
    padding: 0.9rem 2rem;
    border: 2px solid var(--primary-color);
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 1rem;
}

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

@media (min-width: 768px) {
    .calculator-card {
        padding: 3rem;
    }
}

/* ===== Features Section ===== */
.features {
    padding: 4rem 0;
}

.section-title {
    text-align: center;
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 3rem;
}

.features-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
}

.feature-card {
    background: var(--white);
    padding: 2rem;
    border-radius: 16px;
    text-align: center;
    box-shadow: 0 4px 15px var(--shadow);
    transition: all 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px var(--shadow-hover);
}

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

.feature-card h3 {
    font-size: 1.25rem;
    color: var(--text-dark);
    margin-bottom: 0.75rem;
}

.feature-card p {
    color: var(--text-light);
    line-height: 1.6;
}

@media (min-width: 640px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 1024px) {
    .features-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* ===== Info Section ===== */
.info-section {
    padding: 4rem 0;
    background: var(--white);
}

.info-content {
    max-width: 800px;
    margin: 0 auto;
}

.info-content h2 {
    font-size: 2rem;
    color: var(--text-dark);
    margin-bottom: 1.5rem;
    text-align: center;
}

.info-content p {
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: 1.5rem;
    font-size: 1.05rem;
}

.flames-list {
    list-style: none;
    margin: 2rem 0;
    padding: 0;
}

.flames-list li {
    padding: 1rem;
    background: var(--bg-gradient-1);
    border-radius: 10px;
    margin-bottom: 0.75rem;
    font-size: 1.1rem;
    color: var(--text-dark);
    border-left: 4px solid var(--primary-color);
}

.flames-list li strong {
    color: var(--primary-color);
    font-weight: 700;
}

.btn-link {
    display: inline-block;
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    font-size: 1.05rem;
    margin-top: 1rem;
    transition: all 0.3s ease;
}

.btn-link:hover {
    color: var(--secondary-color);
    transform: translateX(5px);
}

/* ===== FAQ Section ===== */
.faq-section {
    padding: 4rem 0;
}

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

.faq-item {
    background: var(--white);
    border-radius: 12px;
    margin-bottom: 1rem;
    overflow: hidden;
    box-shadow: 0 2px 8px var(--shadow);
}

.faq-question {
    width: 100%;
    padding: 1.5rem;
    background: none;
    border: none;
    text-align: left;
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-dark);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all 0.3s ease;
}

.faq-question:hover {
    background: var(--bg-gradient-1);
}

.faq-icon {
    font-size: 1.5rem;
    color: var(--primary-color);
    font-weight: 400;
    transition: transform 0.3s ease;
}

.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 1.5rem 1.5rem;
    color: var(--text-light);
    line-height: 1.7;
}

.faq-answer strong {
    color: var(--text-dark);
    font-weight: 600;
}

/* ===== Footer ===== */
.footer {
    background: var(--text-dark);
    color: var(--white);
    padding: 3rem 0 1.5rem;
    margin-top: 4rem;
}

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

.footer-section h3 {
    color: var(--primary-color);
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.footer-section h4 {
    color: var(--white);
    font-size: 1.1rem;
    margin-bottom: 1rem;
}

.footer-section p {
    color: #cbd5e0;
    line-height: 1.6;
    font-size: 0.95rem;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.75rem;
}

.footer-links a {
    color: #cbd5e0;
    text-decoration: none;
    transition: color 0.3s ease;
}

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

.social-links {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}

.social-links a {
    font-size: 1.5rem;
    transition: transform 0.3s ease;
}

.social-links a:hover {
    transform: translateY(-3px);
}

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

.footer-bottom p {
    color: #cbd5e0;
    font-size: 0.9rem;
}

@media (min-width: 768px) {
    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 1024px) {
    .footer-content {
        grid-template-columns: repeat(4, 1fr);
    }
}

/* ===== Mobile Navigation Toggle ===== */
@media (max-width: 767px) {
    .nav-menu.active {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--white);
        padding: 1rem;
        box-shadow: 0 4px 10px var(--shadow);
    }
    
    .nav-menu li {
        padding: 0.75rem 0;
        border-bottom: 1px solid var(--border-color);
    }
    
    .nav-menu li:last-child {
        border-bottom: none;
    }
}

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

.mt-1 { margin-top: 1rem; }
.mt-2 { margin-top: 2rem; }
.mb-1 { margin-bottom: 1rem; }
.mb-2 { margin-bottom: 2rem; }

/* ===== Accessibility ===== */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    margin: -1px;
    padding: 0;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
}

/* ===== Print Styles ===== */
@media print {
    .header,
    .footer,
    .mobile-toggle {
        display: none;
    }
}