/* ============================================
   CSS Custom Properties (Design Tokens)
   ============================================ */
:root {
    /* Colors */
    --color-primary: #0066cc;
    --color-primary-dark: #0052a3;
    --color-primary-light: #3385d6;
    --color-text: #333;
    --color-text-light: #666;
    --color-text-muted: #999;
    --color-background: #fff;
    --color-background-alt: #f9f9f9;
    --color-background-dark: #333;
    --color-background-darker: #222;
    --color-border: #eee;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --section-padding: 100px;

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.2rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;
    --font-size-3xl: 2.5rem;
    --font-size-4xl: 4rem;
    --line-height: 1.6;

    /* Layout */
    --max-width: 1200px;
    --border-radius: 8px;
    --border-radius-sm: 5px;
    --nav-height: 70px;

    /* Shadows */
    --shadow-sm: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 15px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.15);

    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--nav-height);
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: var(--line-height);
    color: var(--color-text);
    background: var(--color-background);
}

/* Skip link for accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-primary);
    color: var(--color-background);
    padding: var(--spacing-sm);
    z-index: 1001;
    transition: top var(--transition-fast);
}

.skip-link:focus {
    top: 0;
}

/* ============================================
   Header & Navigation
   ============================================ */
header {
    position: fixed;
    top: 0;
    width: 100%;
    background: var(--color-background);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
}

nav {
    width: 100%;
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--spacing-sm) var(--spacing-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-text);
    text-decoration: none;
    transition: color var(--transition-base);
}

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

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

.nav-links a {
    text-decoration: none;
    color: var(--color-text);
    font-weight: 500;
    transition: color var(--transition-base);
    padding: var(--spacing-xs) 0;
}

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

/* Mobile menu toggle button */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    justify-content: space-around;
    width: 30px;
    height: 24px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0;
    z-index: 1001;
}

.hamburger-line {
    display: block;
    width: 100%;
    height: 3px;
    background: var(--color-text);
    border-radius: 2px;
    transition: all var(--transition-base);
}

/* ============================================
   Main Content & Sections
   ============================================ */
main {
    padding-top: var(--nav-height);
}

section {
    padding: var(--section-padding) var(--spacing-lg);
    max-width: var(--max-width);
    margin: 0 auto;
}

h2 {
    font-size: var(--font-size-3xl);
    margin-bottom: var(--spacing-xl);
    text-align: center;
}

/* ============================================
   Hero Section
   ============================================ */
#hero {
    min-height: calc(100vh - var(--nav-height));
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    gap: var(--spacing-md);
}

#hero h1 {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    background: linear-gradient(135deg, var(--color-text) 0%, var(--color-primary) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-tagline {
    font-size: var(--font-size-xl);
    color: var(--color-text-light);
    font-weight: 500;
}

.hero-description {
    font-size: var(--font-size-lg);
    color: var(--color-text-muted);
    max-width: 600px;
}

.hero-cta {
    display: inline-block;
    margin-top: var(--spacing-md);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--color-primary);
    color: var(--color-background);
    text-decoration: none;
    border-radius: var(--border-radius-sm);
    font-weight: 600;
    transition: all var(--transition-base);
}

.hero-cta:hover {
    background: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

/* ============================================
   Projects Section
   ============================================ */
#projects {
    background: var(--color-background-alt);
    max-width: 100%;
    padding-left: var(--spacing-lg);
    padding-right: var(--spacing-lg);
}

#projects h2,
#projects .projects-grid {
    max-width: var(--max-width);
    margin-left: auto;
    margin-right: auto;
}

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

.project-card {
    background: var(--color-background);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
    position: relative;
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.project-card h3 {
    margin-bottom: var(--spacing-sm);
    color: var(--color-text);
    font-size: var(--font-size-xl);
}

.project-card p {
    color: var(--color-text-light);
    margin-bottom: var(--spacing-md);
}

.project-tag {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--color-background-alt);
    color: var(--color-primary);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-sm);
    font-weight: 500;
}

/* ============================================
   Pricing Section
   ============================================ */
#pricing {
    padding-bottom: calc(var(--section-padding) + 20px);
}

.pricing-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    align-items: start;
}

.pricing-card {
    background: var(--color-background);
    padding: var(--spacing-lg) var(--spacing-lg) var(--spacing-xl);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    text-align: center;
    border: 2px solid transparent;
    transition: all var(--transition-base);
    position: relative;
}

.pricing-card:hover {
    border-color: var(--color-primary);
    transform: translateY(-3px);
}

.pricing-card.featured {
    border-color: var(--color-primary);
    transform: scale(1.05);
    box-shadow: var(--shadow-lg);
}

.pricing-card.featured:hover {
    transform: scale(1.07);
}

.featured-badge {
    position: absolute;
    top: -12px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--color-primary);
    color: var(--color-background);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-sm);
    font-weight: 600;
}

.pricing-card h3 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-sm);
}

.price {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
}

.price-period {
    font-size: var(--font-size-lg);
    font-weight: 400;
    color: var(--color-text-light);
}

.pricing-desc {
    color: var(--color-text-light);
    font-size: var(--font-size-sm);
    margin-bottom: var(--spacing-md);
}

.pricing-cta {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--color-primary);
    color: var(--color-background);
    text-decoration: none;
    border-radius: var(--border-radius-sm);
    font-weight: 600;
    transition: all var(--transition-base);
    width: 100%;
    max-width: 200px;
}

.pricing-cta:hover {
    background: var(--color-primary-dark);
}

/* ============================================
   Contact Section
   ============================================ */
#contact {
    text-align: center;
    background: var(--color-background-dark);
    color: var(--color-background);
    max-width: 100%;
    padding-left: var(--spacing-lg);
    padding-right: var(--spacing-lg);
}

.contact-content {
    max-width: var(--max-width);
    margin: 0 auto;
}

#contact h2 {
    color: var(--color-background);
}

.contact-intro {
    margin-bottom: var(--spacing-xl);
    font-size: var(--font-size-lg);
    color: rgba(255, 255, 255, 0.9);
}

.contact-links {
    display: flex;
    gap: var(--spacing-sm);
    justify-content: center;
    flex-wrap: wrap;
}

.cta-button {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--color-primary);
    color: var(--color-background);
    text-decoration: none;
    border-radius: var(--border-radius-sm);
    font-weight: 600;
    transition: all var(--transition-base);
}

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

.cta-button.secondary {
    background: transparent;
    border: 2px solid var(--color-background);
}

.cta-button.secondary:hover {
    background: var(--color-background);
    color: var(--color-text);
}

.button-icon {
    font-size: var(--font-size-lg);
}

/* ============================================
   Back to Top Button
   ============================================ */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--color-primary);
    color: var(--color-background);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    font-size: var(--font-size-xl);
    display: flex;
    align-items: center;
    justify-content: center;
    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 {
    background: var(--color-primary-dark);
    transform: translateY(-3px);
}

.back-to-top:focus {
    outline: 2px solid var(--color-primary-light);
    outline-offset: 2px;
}

/* ============================================
   Footer
   ============================================ */
footer {
    text-align: center;
    padding: var(--spacing-lg);
    background: var(--color-background-darker);
    color: var(--color-text-muted);
}

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

/* Tablet breakpoint */
@media (max-width: 1024px) {
    :root {
        --section-padding: 80px;
    }

    #hero h1 {
        font-size: var(--font-size-3xl);
    }

    .hero-tagline {
        font-size: var(--font-size-lg);
    }

    .pricing-card.featured {
        transform: scale(1.02);
    }
}

/* Mobile breakpoint */
@media (max-width: 768px) {
    :root {
        --section-padding: 60px;
        --spacing-lg: 1.5rem;
    }

    /* Mobile navigation */
    .mobile-menu-toggle {
        display: flex;
    }

    .nav-links {
        position: fixed;
        top: var(--nav-height);
        left: 0;
        right: 0;
        background: var(--color-background);
        flex-direction: column;
        padding: var(--spacing-lg);
        gap: var(--spacing-sm);
        box-shadow: var(--shadow-md);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-base);
    }

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

    .nav-links a {
        display: block;
        padding: var(--spacing-sm);
        text-align: center;
        border-radius: var(--border-radius-sm);
    }

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

    /* Hamburger animation when menu is open */
    .mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(2) {
        opacity: 0;
    }

    .mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }

    /* Hero adjustments */
    #hero h1 {
        font-size: var(--font-size-2xl);
    }

    .hero-tagline {
        font-size: var(--font-size-base);
    }

    .hero-description {
        font-size: var(--font-size-base);
        padding: 0 var(--spacing-sm);
    }

    /* Section headings */
    h2 {
        font-size: var(--font-size-2xl);
    }

    /* Projects grid */
    .projects-grid {
        grid-template-columns: 1fr;
    }

    /* Pricing adjustments */
    .pricing-grid {
        grid-template-columns: 1fr;
        max-width: 400px;
        margin: 0 auto;
    }

    .pricing-card.featured {
        transform: none;
        order: -1;
    }

    .pricing-card.featured:hover {
        transform: translateY(-3px);
    }

    /* Back to top button */
    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 45px;
        height: 45px;
    }
}

/* Small mobile breakpoint */
@media (max-width: 480px) {
    .nav-container {
        padding: var(--spacing-sm);
    }

    .logo {
        font-size: var(--font-size-lg);
    }

    .contact-links {
        flex-direction: column;
        align-items: center;
    }

    .cta-button {
        width: 100%;
        max-width: 250px;
        justify-content: center;
    }
}

/* Reduced motion preference */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    html {
        scroll-behavior: auto;
    }
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --color-primary: #0044aa;
        --shadow-sm: 0 2px 5px rgba(0, 0, 0, 0.3);
        --shadow-md: 0 4px 10px rgba(0, 0, 0, 0.3);
    }

    .project-card,
    .pricing-card {
        border: 2px solid var(--color-text);
    }
}

/* Print styles */
@media print {
    header,
    .back-to-top,
    .hero-cta,
    .pricing-cta,
    .cta-button {
        display: none;
    }

    main {
        padding-top: 0;
    }

    section {
        padding: var(--spacing-lg) 0;
        page-break-inside: avoid;
    }

    .project-card,
    .pricing-card {
        box-shadow: none;
        border: 1px solid var(--color-text);
    }
}