/* ===========================================
   CSS Variables & Reset
   =========================================== */
:root {
    /* Light Mode Colors */
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --accent-color: #3b82f6;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --border-color: #e5e7eb;
    --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);

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

    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;

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

/* Dark Mode Variables */
body.dark-mode {
    --primary-color: #3b82f6;
    --secondary-color: #60a5fa;
    --accent-color: #2563eb;
    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --bg-primary: #111827;
    --bg-secondary: #1f2937;
    --bg-tertiary: #374151;
    --border-color: #4b5563;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.6);
}

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

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color var(--transition-base), color var(--transition-base);
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

img {
    max-width: 100%;
    height: auto;
}

/* ===========================================
   Navigation
   =========================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: var(--bg-primary);
    box-shadow: var(--shadow-md);
    z-index: 1000;
    transition: background-color var(--transition-base), box-shadow var(--transition-base);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--primary-color);
    transition: color var(--transition-fast);
}

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

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

.nav-link {
    color: var(--text-primary);
    font-weight: 500;
    transition: color var(--transition-fast);
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: width var(--transition-base);
}

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

.nav-link:hover::after {
    width: 100%;
}

.theme-toggle {
    background: none;
    border: 2px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.5rem;
    border-radius: 50%;
    cursor: pointer;
    font-size: var(--font-size-lg);
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
}

.theme-toggle:hover {
    background-color: var(--bg-tertiary);
    border-color: var(--primary-color);
    transform: rotate(15deg);
}

/* ===========================================
   Hero Section
   =========================================== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 6rem 2rem 4rem;
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
    position: relative;
}

.hero-container {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.hero-content {
    animation: fadeInUp 1s ease-out;
}

.profile-image-wrapper {
    margin-bottom: var(--spacing-lg);
}

.profile-image {
    width: 150px;
    height: 150px;
    margin: 0 auto;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    color: white;
    box-shadow: var(--shadow-xl);
    animation: float 3s ease-in-out infinite;
}

.hero-title {
    font-size: var(--font-size-5xl);
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.hero-subtitle {
    font-size: var(--font-size-xl);
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
    font-weight: 600;
    min-height: 2.5rem;
}

.hero-description {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

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

.btn {
    padding: 0.875rem 2rem;
    border-radius: 0.5rem;
    font-weight: 600;
    font-size: var(--font-size-base);
    transition: all var(--transition-base);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border: 2px solid transparent;
    cursor: pointer;
}

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

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

.btn-secondary {
    background-color: var(--text-primary);
    color: var(--bg-primary);
    box-shadow: var(--shadow-md);
}

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

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

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

.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    animation: bounce 2s infinite;
}

.scroll-indicator a {
    color: var(--primary-color);
    font-size: var(--font-size-2xl);
    transition: color var(--transition-fast);
}

.scroll-indicator a:hover {
    color: var(--secondary-color);
}

/* ===========================================
   Common Section Styles
   =========================================== */
section {
    padding: var(--spacing-2xl) 2rem;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
}

.section-title {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    text-align: center;
    margin-bottom: var(--spacing-xl);
    color: var(--text-primary);
    position: relative;
    padding-bottom: var(--spacing-md);
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border-radius: 2px;
}

/* ===========================================
   About Section
   =========================================== */
.about {
    background-color: var(--bg-secondary);
}

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

.about-text {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.8;
}

.about-text strong {
    color: var(--primary-color);
    font-weight: 600;
}

/* ===========================================
   Skills Section
   =========================================== */
.skills {
    background-color: var(--bg-primary);
}

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

.skill-category {
    background-color: var(--bg-secondary);
    padding: var(--spacing-xl);
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
    border: 2px solid transparent;
}

.skill-category:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.skill-icon {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-md);
    color: white;
    font-size: var(--font-size-2xl);
}

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

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

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

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

/* ===========================================
   Contact Section
   =========================================== */
.contact {
    background-color: var(--bg-secondary);
}

.contact-intro {
    text-align: center;
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.contact-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    max-width: 900px;
    margin: 0 auto;
}

.contact-card {
    background-color: var(--bg-primary);
    padding: var(--spacing-xl);
    border-radius: 1rem;
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
    border: 2px solid transparent;
    cursor: pointer;
}

.contact-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.contact-icon {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto var(--spacing-md);
    font-size: var(--font-size-3xl);
    color: white;
    transition: transform var(--transition-base);
}

.contact-card:hover .contact-icon {
    transform: scale(1.1);
}

.contact-icon.linkedin {
    background: linear-gradient(135deg, #0077b5, #005885);
}

.contact-icon.github {
    background: linear-gradient(135deg, #333, #000);
}

.contact-icon.resume {
    background: linear-gradient(135deg, #e74c3c, #c0392b);
}

.contact-card h3 {
    font-size: var(--font-size-xl);
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.contact-card p {
    color: var(--text-secondary);
    font-size: var(--font-size-base);
}

/* ===========================================
   Footer
   =========================================== */
.footer {
    background-color: var(--bg-primary);
    padding: var(--spacing-xl) 2rem;
    text-align: center;
    border-top: 1px solid var(--border-color);
}

.footer p {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    margin-bottom: 0.5rem;
}

.footer-subtitle {
    font-size: var(--font-size-xs);
    opacity: 0.7;
}

.footer-updated {
    font-size: var(--font-size-xs);
    opacity: 0.7;
    font-style: italic;
}

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

@keyframes float {
    0%, 100% {
        transform: translateY(0px);
    }
    50% {
        transform: translateY(-10px);
    }
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateX(-50%) translateY(0);
    }
    40% {
        transform: translateX(-50%) translateY(-10px);
    }
    60% {
        transform: translateX(-50%) translateY(-5px);
    }
}

.fade-in {
    animation: fadeInUp 1s ease-out;
}

/* ===========================================
   Responsive Design
   =========================================== */
@media (max-width: 768px) {
    .nav-menu {
        gap: var(--spacing-md);
    }

    .nav-link {
        font-size: var(--font-size-sm);
    }

    .hero {
        padding: 5rem 1.5rem 3rem;
    }

    .hero-title {
        font-size: var(--font-size-3xl);
    }

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

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

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

    .btn {
        width: 100%;
        justify-content: center;
    }

    .profile-image {
        width: 120px;
        height: 120px;
        font-size: 3rem;
    }

    .section-title {
        font-size: var(--font-size-3xl);
    }

    section {
        padding: var(--spacing-xl) 1.5rem;
    }

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

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

@media (max-width: 480px) {
    .nav-container {
        padding: 0.75rem 1rem;
    }

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

    .nav-link {
        font-size: var(--font-size-xs);
    }

    .theme-toggle {
        width: 36px;
        height: 36px;
        font-size: var(--font-size-base);
    }

    .hero-title {
        font-size: var(--font-size-2xl);
    }

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

    .section-title {
        font-size: var(--font-size-2xl);
    }
}

/* ===========================================
   Utility Classes
   =========================================== */
.text-center {
    text-align: center;
}

.mt-1 { margin-top: var(--spacing-xs); }
.mt-2 { margin-top: var(--spacing-sm); }
.mt-3 { margin-top: var(--spacing-md); }
.mt-4 { margin-top: var(--spacing-lg); }
.mt-5 { margin-top: var(--spacing-xl); }

.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-3 { margin-bottom: var(--spacing-md); }
.mb-4 { margin-bottom: var(--spacing-lg); }
.mb-5 { margin-bottom: var(--spacing-xl); }