/* ============================================
   CSS Variables for Theming
   ============================================ */
:root {
    /* Light Mode Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-card: #ffffff;
    --text-primary: #1a1a1a;
    --text-secondary: #6c757d;
    --border-color: #dee2e6;
    --accent-primary: #0066cc;
    --accent-hover: #0052a3;
    --shadow: rgba(0, 0, 0, 0.1);
    --shadow-hover: rgba(0, 0, 0, 0.15);

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

    /* Border radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;

    /* Transitions */
    --transition: all 0.3s ease;

    /* Gradient colors for animations */
    --gradient-1: #0066cc;
    --gradient-2: #00a8cc;
    --gradient-3: #0052a3;
}

[data-theme="dark"] {
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-card: #1c2128;
    --text-primary: #e6edf3;
    --text-secondary: #7d8590;
    --border-color: #30363d;
    --accent-primary: #58a6ff;
    --accent-hover: #79b8ff;
    --shadow: rgba(0, 0, 0, 0.3);
    --shadow-hover: rgba(0, 0, 0, 0.5);

    /* Dark mode gradients */
    --gradient-1: #58a6ff;
    --gradient-2: #79b8ff;
    --gradient-3: #388bfd;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: var(--transition);
}

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

/* ============================================
   Navigation
   ============================================ */
.navbar {
    position: sticky;
    top: 0;
    background-color: var(--bg-card);
    border-bottom: 1px solid var(--border-color);
    padding: var(--spacing-sm) 0;
    z-index: 1000;
    box-shadow: 0 2px 4px var(--shadow);
}

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

.nav-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-primary);
}

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

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

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

.theme-toggle {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.theme-toggle:hover {
    background-color: var(--bg-secondary);
}

/* ============================================
   Hero Section
   ============================================ */
@keyframes gradientShift {
    0% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
    100% {
        background-position: 0% 50%;
    }
}

.hero {
    padding: var(--spacing-xl) 0;
    background: linear-gradient(-45deg, var(--gradient-1), var(--gradient-2), var(--gradient-3), var(--bg-secondary));
    background-size: 400% 400%;
    animation: gradientShift 15s ease infinite;
    min-height: 60vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg-primary);
    opacity: 0.85;
    z-index: 0;
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: var(--spacing-sm);
    background: linear-gradient(135deg, var(--accent-primary), #0052a3);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    font-weight: 600;
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
    line-height: 1.8;
}

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

/* ============================================
   Buttons
   ============================================ */
.btn {
    display: inline-block;
    padding: 0.75rem 2rem;
    border-radius: var(--radius-md);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    border: 2px solid transparent;
}

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

.btn-primary:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--shadow-hover);
}

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

.btn-secondary:hover {
    background-color: var(--accent-primary);
    color: white;
    transform: translateY(-2px);
}

/* ============================================
   Sections
   ============================================ */
.section {
    padding: var(--spacing-xl) 0;
}

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

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    text-align: center;
    color: var(--text-primary);
}

/* ============================================
   About Section
   ============================================ */
.about-content {
    max-width: 800px;
    margin: 0 auto;
    font-size: 1.125rem;
    line-height: 1.8;
}

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

/* ============================================
   Projects Section
   ============================================ */
.projects-grid {
    display: grid;
    gap: var(--spacing-lg);
}

.project-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: all 0.4s cubic-bezier(0.165, 0.84, 0.44, 1);
    position: relative;
    overflow: hidden;
}

.project-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(88, 166, 255, 0.1), transparent);
    transition: left 0.5s;
}

.project-card:hover::before {
    left: 100%;
}

.project-card:hover {
    transform: translateY(-8px) scale(1.02);
    box-shadow: 0 12px 40px var(--shadow-hover), 0 0 0 1px var(--accent-primary);
    border-color: var(--accent-primary);
}

.project-header {
    margin-bottom: var(--spacing-md);
}

.project-title {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.project-tags {
    display: flex;
    gap: var(--spacing-xs);
    flex-wrap: wrap;
    margin-bottom: var(--spacing-sm);
}

.tag {
    background-color: var(--accent-primary);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 500;
}

.project-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.7;
}

.project-highlights {
    margin-bottom: var(--spacing-md);
}

.project-highlights h4 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.project-highlights ul {
    list-style: none;
    padding-left: 0;
}

.project-highlights li {
    padding: var(--spacing-xs) 0;
    color: var(--text-secondary);
    line-height: 1.7;
}

.project-highlights li::before {
    content: "▸ ";
    color: var(--accent-primary);
    font-weight: bold;
    margin-right: var(--spacing-xs);
}

.project-highlights strong {
    color: var(--text-primary);
}

.project-tech {
    margin-bottom: var(--spacing-md);
}

.project-tech h4 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.tech-badges {
    display: flex;
    gap: var(--spacing-xs);
    flex-wrap: wrap;
}

.tech-badges img {
    height: 28px;
}

.project-diagram {
    margin-top: var(--spacing-md);
    padding: var(--spacing-md);
    background-color: var(--bg-secondary);
    border-radius: var(--radius-md);
}

.project-diagram h4 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.mermaid {
    background-color: transparent;
}

/* ============================================
   Skills Section
   ============================================ */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.skill-category {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    transition: var(--transition);
}

.skill-category:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--shadow-hover);
}

.skill-category h3 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.skill-badges {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.skill-badges img {
    height: 32px;
}

/* ============================================
   Contact Section
   ============================================ */
.contact-content {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

.contact-intro {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
}

.contact-links {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.contact-link {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    text-decoration: none;
    color: var(--text-primary);
    transition: var(--transition);
}

.contact-link:hover {
    background-color: var(--accent-primary);
    color: white;
    border-color: var(--accent-primary);
    transform: translateY(-2px);
}

.contact-icon {
    font-size: 1.5rem;
}

/* ============================================
   Footer
   ============================================ */
.footer {
    background-color: var(--bg-card);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-lg) 0;
    text-align: center;
    color: var(--text-secondary);
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }

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

    .section-title {
        font-size: 2rem;
    }

    .nav-links {
        gap: var(--spacing-sm);
    }

    .nav-links a {
        font-size: 0.875rem;
    }

    .container {
        padding: 0 var(--spacing-sm);
    }

    .skills-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }

    .hero-cta {
        flex-direction: column;
    }

    .btn {
        width: 100%;
        text-align: center;
    }
}

/* ============================================
   Scroll Animations
   ============================================ */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* Elements that should animate on scroll */
.section {
    opacity: 0;
    animation: fadeIn 0.6s ease-out forwards;
}

.animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.animate-on-scroll.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Stagger animations for skill badges */
.skill-badges img {
    opacity: 0;
    transform: scale(0.8);
    transition: opacity 0.3s ease-out, transform 0.3s ease-out;
}

.skill-category.visible .skill-badges img {
    opacity: 1;
    transform: scale(1);
}

.skill-category.visible .skill-badges img:nth-child(1) { transition-delay: 0.1s; }
.skill-category.visible .skill-badges img:nth-child(2) { transition-delay: 0.15s; }
.skill-category.visible .skill-badges img:nth-child(3) { transition-delay: 0.2s; }
.skill-category.visible .skill-badges img:nth-child(4) { transition-delay: 0.25s; }
.skill-category.visible .skill-badges img:nth-child(5) { transition-delay: 0.3s; }
.skill-category.visible .skill-badges img:nth-child(6) { transition-delay: 0.35s; }
.skill-category.visible .skill-badges img:nth-child(7) { transition-delay: 0.4s; }
.skill-category.visible .skill-badges img:nth-child(8) { transition-delay: 0.45s; }

/* Tech badge hover effects */
.tech-badges img, .skill-badges img {
    transition: transform 0.3s ease, filter 0.3s ease;
    cursor: pointer;
}

.tech-badges img:hover, .skill-badges img:hover {
    transform: translateY(-4px) scale(1.1);
    filter: brightness(1.2);
}