/* ===== CSS Variables ===== */
:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --secondary-color: #64748b;
    --accent-color: #f59e0b;
    --text-primary: #1e293b;
    --text-secondary: #475569;
    --text-light: #94a3b8;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-dark: #0f172a;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
        'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
        sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    line-height: 1.6;
    font-size: 16px;
}

/* ===== Typography ===== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

h1 {
    font-size: clamp(2rem, 5vw, 3.5rem);
}

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

h3 {
    font-size: clamp(1.25rem, 3vw, 1.75rem);
}

p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

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

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

/* ===== Container ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* ===== Navigation ===== */
.navbar {
    background-color: var(--bg-primary);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
    border-bottom: 1px solid var(--border-color);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

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

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

.nav-links a {
    color: var(--text-secondary);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: var(--transition);
}

.nav-links a:hover::after,
.nav-links a.active::after {
    width: 100%;
}

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

/* ===== Hero Section ===== */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 6rem 0;
    text-align: center;
}

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

.hero h1 {
    color: white;
    margin-bottom: 1rem;
}

.highlight {
    color: var(--accent-color);
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    font-weight: 600;
}

.hero-description {
    font-size: 1.125rem;
    margin-bottom: 2rem;
    opacity: 0.95;
}

/* ===== Page Header ===== */
.page-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 4rem 0;
    text-align: center;
}

.page-header h1 {
    color: white;
}

.page-subtitle {
    font-size: 1.25rem;
    opacity: 0.95;
}

/* ===== Buttons ===== */
.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    border-radius: 0.5rem;
    font-weight: 600;
    text-align: center;
    transition: var(--transition);
    cursor: pointer;
    border: none;
    font-size: 1rem;
}

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

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

.btn-secondary {
    background-color: transparent;
    color: white;
    border: 2px solid white;
}

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

.cta-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* ===== Sections ===== */
section {
    padding: 5rem 0;
}

section:nth-child(even) {
    background-color: var(--bg-secondary);
}

.content-section,
.skills-section,
.projects-section,
.approach-section,
.technologies-showcase {
    padding: 5rem 0;
}

.intro-content {
    max-width: 900px;
    margin: 0 auto;
}

/* ===== Cards Grid ===== */
.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.card {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    border: 1px solid var(--border-color);
    display: block;
    color: inherit;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

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

.card h3 {
    color: var(--text-primary);
    margin-bottom: 0.75rem;
}

.card p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.card-link {
    color: var(--primary-color);
    font-weight: 600;
}

/* ===== Projects Grid ===== */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.project-card {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

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

.project-card h3 {
    margin-bottom: 1rem;
}

.project-link {
    display: inline-block;
    margin-top: 1rem;
    color: var(--primary-color);
    font-weight: 600;
}

.project-link:hover {
    text-decoration: underline;
}

/* ===== Project List (Detailed) ===== */
.project-list {
    display: flex;
    flex-direction: column;
    gap: 3rem;
    margin-top: 3rem;
}

.project-detail {
    background-color: var(--bg-primary);
    padding: 2.5rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

.project-header {
    margin-bottom: 1.5rem;
}

.project-detail h3 {
    margin-bottom: 1rem;
}

.project-detail ul {
    margin: 1rem 0 1.5rem 1.5rem;
    color: var(--text-secondary);
}

.project-detail li {
    margin-bottom: 0.5rem;
}

/* ===== Tech Tags ===== */
.tech-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1rem;
}

.tag {
    background-color: var(--bg-secondary);
    color: var(--primary-color);
    padding: 0.375rem 0.875rem;
    border-radius: 9999px;
    font-size: 0.875rem;
    font-weight: 600;
    border: 1px solid var(--border-color);
}

/* ===== Skills Grid ===== */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.skill-card {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

.skill-card h3 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--border-color);
}

.skill-card ul {
    list-style: none;
}

.skill-card li {
    padding: 0.5rem 0;
    color: var(--text-secondary);
    position: relative;
    padding-left: 1.5rem;
}

.skill-card li::before {
    content: '▹';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

/* ===== Tech Stack ===== */
.tech-categories {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.tech-category h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.tech-items {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.tech-item {
    background-color: var(--bg-primary);
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    border: 1px solid var(--border-color);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: var(--transition);
}

.tech-item:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateY(-2px);
}

/* ===== Approach Grid ===== */
.approach-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.approach-item {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.approach-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.approach-item h3 {
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

.approach-item p {
    font-size: 0.95rem;
}

/* ===== Technologies Showcase ===== */
.tech-showcase-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.tech-showcase-item {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

.tech-showcase-item h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

/* ===== CTA Section ===== */
.cta-section {
    text-align: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.cta-section h2 {
    color: white;
}

.cta-section p {
    color: white;
    opacity: 0.95;
    font-size: 1.125rem;
    margin-bottom: 2rem;
}

/* ===== Footer ===== */
footer {
    background-color: var(--bg-dark);
    color: white;
    padding: 2rem 0;
    text-align: center;
}

footer .container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

footer p {
    color: var(--text-light);
}

.footer-links {
    display: flex;
    gap: 2rem;
}

.footer-links a {
    color: var(--text-light);
}

.footer-links a:hover {
    color: white;
}

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
    .container {
        padding: 0 1rem;
    }

    .navbar .container {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
    }

    .nav-links {
        flex-wrap: wrap;
        gap: 1rem;
        justify-content: center;
    }

    .hero,
    .page-header {
        padding: 3rem 0;
    }

    section {
        padding: 3rem 0;
    }

    .cards-grid,
    .projects-grid {
        grid-template-columns: 1fr;
    }

    .cta-buttons {
        flex-direction: column;
        align-items: stretch;
    }

    .btn {
        width: 100%;
    }

    h1 {
        font-size: 2rem;
    }

    h2 {
        font-size: 1.75rem;
    }
}

@media (max-width: 480px) {
    .nav-links {
        gap: 0.5rem;
        font-size: 0.875rem;
    }

    .hero-subtitle {
        font-size: 1.25rem;
    }

    .hero-description {
        font-size: 1rem;
    }

    .project-detail,
    .card,
    .skill-card {
        padding: 1.5rem;
    }
}

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

.card,
.project-card,
.project-detail,
.skill-card,
.approach-item {
    animation: fadeIn 0.6s ease-out;
}

/* ===== Accessibility ===== */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus styles for keyboard navigation */
a:focus,
button:focus,
.btn:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* ===== Print Styles ===== */
@media print {
    .navbar,
    .cta-section,
    footer {
        display: none;
    }

    body {
        font-size: 12pt;
    }

    .container {
        max-width: 100%;
    }
}