/* ============================================
   CSS Variables for Themes
   ============================================ */

:root {
    /* Light Theme Colors */
    --color-bg: #FAFAFA;
    --color-bg-alt: #F5F5F5;
    --color-bg-dark: #2A2A2A;
    --color-text: #1A1A1A;
    --color-text-secondary: #666666;
    --color-text-tertiary: #999999;
    --color-border: #E0E0E0;
    --color-accent: #2A2A2A;
    --color-accent-hover: #000000;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;
    --spacing-xxl: 8rem;
    
    /* Typography */
    --font-primary: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-size-base: 1.125rem;
    --font-size-sm: 0.9375rem;
    --font-size-lg: 1.375rem;
    --font-size-xl: 2rem;
    --font-size-xxl: 3rem;
    --line-height-base: 1.7;
    --line-height-tight: 1.3;
    
    /* Container */
    --container-width: 1200px;
    
    /* Transitions */
    --transition-smooth: all 0.3s ease;
}

/* Dark Theme */
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --color-bg: #1A1A1A;
        --color-bg-alt: #242424;
        --color-bg-dark: #0F0F0F;
        --color-text: #FAFAFA;
        --color-text-secondary: #B3B3B3;
        --color-text-tertiary: #808080;
        --color-border: #333333;
        --color-accent: #FAFAFA;
        --color-accent-hover: #FFFFFF;
    }
}

[data-theme="dark"] {
    --color-bg: #1A1A1A;
    --color-bg-alt: #242424;
    --color-bg-dark: #0F0F0F;
    --color-text: #FAFAFA;
    --color-text-secondary: #B3B3B3;
    --color-text-tertiary: #808080;
    --color-border: #333333;
    --color-accent: #FAFAFA;
    --color-accent-hover: #FFFFFF;
}

/* ============================================
   Reset & Base Styles
   ============================================ */

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

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

body {
    font-family: var(--font-primary);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    color: var(--color-text);
    background-color: var(--color-bg);
    transition: background-color 0.3s ease, color 0.3s ease;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   Typography
   ============================================ */

h1, h2, h3, h4, h5, h6 {
    line-height: var(--line-height-tight);
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
}

h1 {
    font-size: var(--font-size-xxl);
}

h2 {
    font-size: var(--font-size-xl);
}

h3 {
    font-size: var(--font-size-lg);
}

p {
    margin-bottom: var(--spacing-sm);
}

strong {
    font-weight: 500;
}

a {
    color: inherit;
    text-decoration: none;
    transition: var(--transition-smooth);
}

/* ============================================
   Layout
   ============================================ */

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.section {
    padding: var(--spacing-xxl) 0;
}

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

.section__description {
    color: var(--color-text-secondary);
    max-width: 42rem;
}

.section__content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    align-items: center;
}

.section__text {
    text-align: left;
}

.section__visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.section--alt {
    background-color: var(--color-bg-alt);
}

.section--dark {
    background-color: var(--color-bg-dark);
}

/* ============================================
   Header & Navigation
   ============================================ */

.header {
    padding: var(--spacing-md) 0;
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    background-color: var(--color-bg);
    z-index: 100;
    transition: var(--transition-smooth);
}

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

.nav__name {
    font-size: var(--font-size-lg);
    font-weight: 500;
}

.nav__controls {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

/* Theme Toggle */
.theme-toggle {
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text);
    transition: var(--transition-smooth);
}

.theme-toggle:hover {
    opacity: 0.7;
}

.theme-toggle__icon::before {
    content: '◐';
    font-size: 1.5rem;
    display: block;
}

/* Language Switcher */
.language-switcher {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.lang-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-size: var(--font-size-sm);
    color: var(--color-text-tertiary);
    transition: var(--transition-smooth);
    padding: var(--spacing-xs);
}

.lang-btn:hover,
.lang-btn.active {
    color: var(--color-text);
}

.lang-divider {
    color: var(--color-text-tertiary);
}

/* ============================================
   Hero Section
   ============================================ */

.hero {
    padding: var(--spacing-xl) 0;
}

.hero__content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    align-items: center;
}

.hero__title {
    font-size: clamp(2rem, 5vw, 3.5rem);
    margin-bottom: var(--spacing-md);
    line-height: 1.2;
}

.hero__subtitle {
    color: var(--color-text-secondary);
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-lg);
    max-width: 32rem;
}

/* ============================================
   Buttons
   ============================================ */

.btn {
    display: inline-block;
    padding: 1rem 2rem;
    font-size: var(--font-size-base);
    border: 2px solid var(--color-accent);
    background: none;
    color: var(--color-accent);
    cursor: pointer;
    transition: var(--transition-smooth);
    text-align: center;
}

.btn:hover {
    background-color: var(--color-accent);
    color: var(--color-bg);
}

.btn--primary {
    background-color: var(--color-accent);
    color: var(--color-bg);
}

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

.btn--secondary {
    /* Uses default button styles */
}

/* ============================================
   Feature List
   ============================================ */

.feature-list {
    list-style: none;
    margin-top: var(--spacing-lg);
}

.feature-list__item {
    margin-bottom: var(--spacing-md);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.feature-list__item strong {
    font-size: var(--font-size-lg);
    color: var(--color-text);
}

.feature-list__item span {
    color: var(--color-text-secondary);
}

/* ============================================
   Process Grid
   ============================================ */

.process-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.process-card {
    text-align: left;
}

.process-card__number {
    font-size: var(--font-size-sm);
    color: var(--color-text-tertiary);
    margin-bottom: var(--spacing-sm);
    font-weight: 500;
}

.process-card__title {
    margin-bottom: var(--spacing-sm);
}

.process-card__text {
    color: var(--color-text-secondary);
}

/* ============================================
   Services Grid
   ============================================ */

.services-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.service-card {
    padding: var(--spacing-lg);
    border: 1px solid var(--color-border);
    transition: var(--transition-smooth);
}

.service-card:hover {
    border-color: var(--color-text-tertiary);
}

.service-card__title {
    margin-bottom: var(--spacing-sm);
}

.service-card__text {
    color: var(--color-text-secondary);
}

/* ============================================
   Stats
   ============================================ */

.stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.stat {
    text-align: center;
}

.stat__number {
    font-size: var(--font-size-xxl);
    font-weight: 500;
    margin-bottom: var(--spacing-xs);
}

.stat__label {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

/* ============================================
   Experience Cards
   ============================================ */

.experience-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.experience-card {
    padding: var(--spacing-lg);
    border-left: 2px solid var(--color-border);
}

.experience-card__text {
    color: var(--color-text-secondary);
}

/* ============================================
   FAQ
   ============================================ */

.faq-list {
    max-width: 48rem;
    margin-top: var(--spacing-lg);
}

.faq-item {
    border-bottom: 1px solid var(--color-border);
    padding: var(--spacing-md) 0;
}

.faq-item__question {
    font-size: var(--font-size-lg);
    cursor: pointer;
    list-style: none;
    padding-right: var(--spacing-md);
    position: relative;
    color: var(--color-text);
}

.faq-item__question::-webkit-details-marker {
    display: none;
}

.faq-item__question::after {
    content: '+';
    position: absolute;
    right: 0;
    font-size: 1.5rem;
    transition: var(--transition-smooth);
}

.faq-item[open] .faq-item__question::after {
    content: '−';
}

.faq-item__answer {
    margin-top: var(--spacing-sm);
    color: var(--color-text-secondary);
    padding-right: var(--spacing-lg);
}

/* ============================================
   Contact
   ============================================ */

.section--contact {
    text-align: center;
}

.contact__intro {
    color: var(--color-text-secondary);
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-xl);
    max-width: 42rem;
    margin-left: auto;
    margin-right: auto;
}

.contact-methods {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    max-width: 32rem;
    margin: 0 auto;
}

.contact-link {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
    border: 1px solid var(--color-border);
    transition: var(--transition-smooth);
}

.contact-link:hover {
    border-color: var(--color-text);
}

.contact-link__label {
    color: var(--color-text-tertiary);
    font-size: var(--font-size-sm);
}

.contact-link__value {
    color: var(--color-text);
}

/* ============================================
   Footer
   ============================================ */

.footer {
    padding: var(--spacing-lg) 0;
    border-top: 1px solid var(--color-border);
}

.footer__text {
    text-align: center;
    color: var(--color-text-tertiary);
    font-size: var(--font-size-sm);
}

/* ============================================
   Visualizations
   ============================================ */

.visualization {
    width: 100%;
    height: 400px;
    min-height: 300px;
}

/* ============================================
   Responsive Design
   ============================================ */

@media (max-width: 768px) {
    :root {
        --font-size-xxl: 2rem;
        --font-size-xl: 1.5rem;
        --spacing-xl: 4rem;
        --spacing-xxl: 5rem;
    }
    
    .hero__content,
    .section__content {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }
    
    .hero__visual,
    .section__visual {
        order: -1;
    }
    
    .process-grid,
    .services-grid {
        grid-template-columns: 1fr;
    }
    
    .stats {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }
    
    .experience-cards {
        grid-template-columns: 1fr;
    }
    
    .visualization {
        height: 300px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .hero__title {
        font-size: 1.75rem;
    }
    
    .hero__subtitle {
        font-size: var(--font-size-base);
    }
    
    .btn {
        padding: 0.875rem 1.5rem;
        width: 100%;
    }
}