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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-primary);
    overflow-x: hidden;
}

/* ===================================
   Design Tokens
   =================================== */
:root {
    /* Colors - Rich Gradient Palette */
    --primary: #8B5CF6;
    --primary-dark: #7C3AED;
    --primary-light: #A78BFA;
    --secondary: #06B6D4;
    --secondary-dark: #0891B2;
    --accent: #EC4899;
    --whatsapp: #25D366;
    --whatsapp-dark: #128C7E;

    /* Gradients - Lighter for white theme */
    --gradient-primary: linear-gradient(135deg, #8B5CF6 0%, #06B6D4 100%);
    --gradient-secondary: linear-gradient(135deg, #EC4899 0%, #8B5CF6 100%);
    --gradient-accent: linear-gradient(135deg, #06B6D4 0%, #10B981 100%);
    --gradient-bg: linear-gradient(135deg, #f0e7ff 0%, #e0f2fe 50%, #f0fdfa 100%);

    /* Background - White theme */
    --bg-primary: #FFFFFF;
    --bg-secondary: #F8FAFC;
    --bg-tertiary: #F1F5F9;
    --bg-glass: rgba(255, 255, 255, 0.9);

    /* Text - Dark for white background */
    --text-primary: #1E293B;
    --text-secondary: #475569;
    --text-muted: #64748B;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;

    /* Typography */
    --font-body: 'Inter', sans-serif;
    --font-heading: 'Merriweather', serif;

    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 1rem;
    --radius-lg: 1.5rem;

    /* Shadows - Softer for light theme */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07), 0 2px 4px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1), 0 4px 6px rgba(0, 0, 0, 0.05);
    --shadow-glow: 0 0 30px rgba(139, 92, 246, 0.15);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 300ms ease;
    --transition-slow: 500ms ease;
}

/* ===================================
   Typography
   =================================== */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-family: var(--font-heading);
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

h1 {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

h2 {
    font-size: clamp(1.75rem, 4vw, 2.5rem);
    font-weight: 700;
}

h3 {
    font-size: clamp(1.5rem, 3vw, 2rem);
    font-weight: 600;
}

h4 {
    font-size: 1.25rem;
    font-weight: 600;
}

p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

a {
    color: var(--secondary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--secondary-dark);
    text-decoration: underline;
}

/* ===================================
   Layout Utilities
   =================================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ===================================
   Glassmorphism Effect - Light Theme
   =================================== */
.glass-effect {
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(139, 92, 246, 0.15);
    box-shadow: var(--shadow-lg);
}

/* ===================================
   Navigation
   =================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(139, 92, 246, 0.1);
    transition: all var(--transition-base);
}

.navbar.scrolled {
    background: rgba(255, 255, 255, 0.98);
    box-shadow: var(--shadow-md);
}

.nav-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) 0;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
}

.logo:hover {
    text-decoration: none;
}

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

.nav-links {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
    align-items: center;
}

.nav-links a {
    color: var(--text-secondary);
    font-weight: 500;
    transition: color var(--transition-fast);
    text-decoration: none;
}

.nav-links a:hover {
    color: var(--primary);
    text-decoration: none;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
}

.mobile-menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    transition: all var(--transition-fast);
}

/* ===================================
   Hero Section
   =================================== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding: calc(80px + var(--spacing-xl)) 0 var(--spacing-2xl);
    background:
        radial-gradient(circle at 20% 50%, rgba(139, 92, 246, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(6, 182, 212, 0.08) 0%, transparent 50%),
        var(--gradient-bg);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background:
        linear-gradient(90deg, transparent 0%, rgba(139, 92, 246, 0.03) 50%, transparent 100%);
    animation: shimmer 8s infinite;
}

@keyframes shimmer {

    0%,
    100% {
        transform: translateX(-100%);
    }

    50% {
        transform: translateX(100%);
    }
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 900px;
    margin: 0 auto;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

/* ===================================
   Calculator Card
   =================================== */
.calculator-card {
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    margin-top: var(--spacing-xl);
    animation: fadeInUp 0.8s ease;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.calculator-header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.calculator-header h2 {
    margin-bottom: var(--spacing-sm);
}

.calculator-header p {
    color: var(--text-muted);
    margin-bottom: 0;
}

.calculator-body {
    max-width: 600px;
    margin: 0 auto;
}

.input-group {
    margin-bottom: var(--spacing-lg);
}

.input-group label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 500;
    color: var(--text-primary);
}

.date-input {
    width: 100%;
    padding: var(--spacing-md);
    background: var(--bg-primary);
    border: 2px solid #E2E8F0;
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 1rem;
    font-family: var(--font-body);
    transition: all var(--transition-base);
}

.date-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.1);
}

.date-input:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

.date-input::-webkit-calendar-picker-indicator {
    cursor: pointer;
}

/* ===================================
   Buttons
   =================================== */
.btn-primary,
.btn-secondary {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-xl);
    border: none;
    border-radius: var(--radius-md);
    font-size: 1.125rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}

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

.btn-primary.loading .btn-text {
    opacity: 0;
}

.btn-primary.loading .btn-loader {
    opacity: 1;
}

.btn-loader {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 24px;
    height: 24px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    opacity: 0;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to {
        transform: translate(-50%, -50%) rotate(360deg);
    }
}

.btn-secondary {
    background: var(--bg-primary);
    color: var(--text-primary);
    border: 2px solid #E2E8F0;
    margin-top: var(--spacing-sm);
}

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

.btn-secondary:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* ===================================
   Results Container
   =================================== */
.results-container {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md) var(--spacing-lg);
    background: linear-gradient(135deg, rgba(139, 92, 246, 0.05) 0%, rgba(6, 182, 212, 0.05) 100%);
    border-radius: var(--radius-md);
    border: 2px solid rgba(139, 92, 246, 0.15);
    box-shadow: var(--shadow-sm);
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

.results-container h3 {
    text-align: center;
    margin-bottom: var(--spacing-md);
    font-size: 1.25rem;
}

.results-grid {
    display: grid;
    gap: 0.5rem;
    margin-bottom: var(--spacing-md);
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.625rem var(--spacing-sm);
    background: rgba(255, 255, 255, 0.6);
    border: 1px solid rgba(139, 92, 246, 0.1);
    border-radius: var(--radius-sm);
    transition: all var(--transition-base);
}

.result-item:hover {
    background: rgba(255, 255, 255, 0.9);
    border-color: rgba(139, 92, 246, 0.3);
    transform: translateX(4px);
    box-shadow: var(--shadow-sm);
}

.result-item.highlight {
    background: var(--gradient-primary);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 1rem;
    font-weight: 600;
}

.result-label {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.9rem;
}

.result-item.highlight .result-label {
    color: white;
    font-size: 1rem;
}

.result-date {
    color: var(--text-primary);
    font-weight: 600;
    font-family: 'Courier New', monospace;
    font-size: 0.875rem;
}

.result-item.highlight .result-date {
    color: white;
    font-size: 1.05rem;
}

/* ===================================
   Article Section
   =================================== */
.article-section {
    padding: var(--spacing-2xl) 0;
    background: var(--bg-secondary);
}

.main-article {
    max-width: 800px;
    margin: 0 auto;
    background: var(--bg-primary);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
}

/* Table of Contents */
.toc {
    background: rgba(139, 92, 246, 0.1);
    border: 1px solid rgba(139, 92, 246, 0.3);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.toc summary {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    cursor: pointer;
    list-style: none;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.toc summary::-webkit-details-marker {
    display: none;
}

.toc summary::before {
    content: '▶';
    transition: transform var(--transition-base);
}

.toc[open] summary::before {
    transform: rotate(90deg);
}

.toc ul {
    margin-top: var(--spacing-md);
    margin-left: var(--spacing-lg);
}

.toc li {
    margin-bottom: var(--spacing-sm);
}

.toc a {
    color: var(--text-secondary);
    transition: color var(--transition-fast);
}

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

/* Article Content */
.article-content {
    font-family: var(--font-heading);
    font-size: 1.125rem;
    line-height: 1.8;
}

.article-content .lead {
    font-size: 1.25rem;
    color: var(--text-primary);
    font-weight: 400;
}

.article-content h2 {
    margin-top: var(--spacing-2xl);
    padding-top: var(--spacing-lg);
    border-top: 2px solid rgba(139, 92, 246, 0.3);
}

.article-content h2:first-of-type {
    margin-top: var(--spacing-xl);
    border-top: none;
}

.article-content h3 {
    margin-top: var(--spacing-xl);
    color: var(--primary);
}

.article-content ul,
.article-content ol {
    margin-left: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
}

.article-content li {
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
}

.article-content code {
    background: rgba(139, 92, 246, 0.2);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: 'Courier New', monospace;
    font-size: 0.9em;
    color: var(--primary);
}

/* Blockquotes */
blockquote {
    margin: var(--spacing-xl) 0;
    padding: var(--spacing-lg);
    background: var(--gradient-secondary);
    border-left: 4px solid var(--accent);
    border-radius: var(--radius-md);
    position: relative;
}

blockquote::before {
    content: '"';
    position: absolute;
    top: -10px;
    left: 10px;
    font-size: 4rem;
    color: rgba(255, 255, 255, 0.2);
    font-family: Georgia, serif;
}

blockquote p {
    color: white;
    font-style: italic;
    margin: 0;
    position: relative;
    z-index: 1;
}

/* Tables */
.comparison-table {
    width: 100%;
    border-collapse: collapse;
    margin: var(--spacing-xl) 0;
    background: rgba(255, 255, 255, 0.02);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.comparison-table thead {
    background: var(--gradient-primary);
}

.comparison-table th {
    padding: var(--spacing-md);
    text-align: left;
    color: white;
    font-weight: 600;
}

.comparison-table td {
    padding: var(--spacing-md);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-secondary);
}

.comparison-table tbody tr:hover {
    background: rgba(255, 255, 255, 0.05);
}

/* Highlight Boxes */
.highlight-box,
.warning-box {
    margin: var(--spacing-xl) 0;
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    border-left: 4px solid;
}

.highlight-box {
    background: rgba(6, 182, 212, 0.1);
    border-color: var(--secondary);
}

.warning-box {
    background: rgba(236, 72, 153, 0.1);
    border-color: var(--accent);
}

.highlight-box h4,
.warning-box h4 {
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.highlight-box p,
.warning-box p {
    margin-bottom: 0;
}

/* References */
.references {
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-xl);
    border-top: 2px solid rgba(255, 255, 255, 0.1);
}

.references li {
    margin-bottom: var(--spacing-sm);
}

/* ===================================
   Footer
   =================================== */
.footer {
    background: var(--bg-secondary);
    padding: var(--spacing-2xl) 0 var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

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

.footer-section h3,
.footer-section h4 {
    margin-bottom: var(--spacing-md);
    font-size: 1.125rem;
}

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

.footer-section li {
    margin-bottom: var(--spacing-sm);
}

.footer-section a {
    color: var(--text-secondary);
    transition: color var(--transition-fast);
}

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

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-muted);
}

.footer-disclaimer {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    background: linear-gradient(135deg, rgba(236, 72, 153, 0.08) 0%, rgba(139, 92, 246, 0.08) 100%);
    border: 1px solid rgba(236, 72, 153, 0.2);
    border-radius: var(--radius-md);
    text-align: center;
}

.footer-disclaimer p {
    margin: 0;
    font-size: 0.875rem;
    line-height: 1.6;
    color: var(--text-secondary);
}

.footer-disclaimer strong {
    color: var(--accent);
    font-weight: 600;
}

/* ===================================
   Back to Top Button
   =================================== */
.back-to-top {
    position: fixed;
    bottom: var(--spacing-md);
    right: var(--spacing-md);
    width: 50px;
    height: 50px;
    background: var(--gradient-primary);
    border: none;
    border-radius: 50%;
    color: white;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-md);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}

/* ===================================
   Responsive Design
   =================================== */
@media (max-width: 768px) {
    .nav-links {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(10px);
        flex-direction: column;
        padding: var(--spacing-lg);
        gap: var(--spacing-md);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-base);
        border-bottom: 2px solid rgba(139, 92, 246, 0.2);
        box-shadow: var(--shadow-md);
    }

    .nav-links.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

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

    .calculator-card {
        padding: var(--spacing-lg);
    }

    .main-article {
        padding: var(--spacing-lg);
    }

    .article-content {
        font-size: 1rem;
    }

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

@media (max-width: 480px) {
    :root {
        --spacing-xl: 2rem;
        --spacing-2xl: 3rem;
    }

    .hero {
        padding: calc(80px + var(--spacing-lg)) 0 var(--spacing-xl);
    }

    .calculator-card {
        padding: var(--spacing-md);
    }

    .results-container {
        padding: var(--spacing-sm) var(--spacing-md);
    }

    .result-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.25rem;
        padding: 0.5rem var(--spacing-sm);
    }

    .result-label,
    .result-date {
        font-size: 0.85rem;
    }

    .result-item.highlight .result-label,
    .result-item.highlight .result-date {
        font-size: 0.95rem;
    }
}

/* ===================================
   Accessibility
   =================================== */
@media (prefers-reduced-motion: reduce) {

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

:focus-visible {
    outline: 3px solid var(--primary);
    outline-offset: 3px;
}

/* Skip to content link for accessibility */
.skip-to-content {
    position: absolute;
    top: -100px;
    left: 0;
    background: var(--primary);
    color: white;
    padding: var(--spacing-sm) var(--spacing-md);
    text-decoration: none;
    border-radius: 0 0 var(--radius-sm) 0;
    z-index: 10000;
    font-weight: 600;
}

.skip-to-content:focus {
    top: 0;
}

/* ===================================
   WhatsApp Share Button
   =================================== */
.whatsapp-share {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--whatsapp);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-md);
    margin-top: var(--spacing-sm);
    width: 100%;
    justify-content: center;
}

.whatsapp-share:hover {
    background: var(--whatsapp-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.whatsapp-share:focus-visible {
    outline: 3px solid var(--whatsapp);
    outline-offset: 3px;
}

.whatsapp-share svg {
    width: 24px;
    height: 24px;
}

/* ===================================
   Print Styles
   =================================== */
@media print {

    .navbar,
    .back-to-top,
    .whatsapp-share,
    .footer {
        display: none;
    }

    body {
        background: white;
        color: black;
    }

    .calculator-card,
    .main-article {
        box-shadow: none;
        border: 1px solid #ccc;
    }
}