/* Professional Portfolio Styles */

:root {
    /* Colors - Navy theme */
    --navy: #0D1B2A;
    --navy-light: #1B2A3D;
    --navy-lighter: #2A3F5F;
    
    /* Grays */
    --gray-50: #FAFAFA;
    --gray-100: #F5F5F5;
    --gray-200: #E5E5E5;
    --gray-300: #D4D4D4;
    --gray-400: #A3A3A3;
    --gray-500: #737373;
    --gray-600: #525252;
    --gray-700: #404040;
    --gray-800: #262626;
    --gray-900: #171717;

    /* Semantic colors */
    --background: #FFFFFF;
    --foreground: var(--navy);
    --card: #FFFFFF;
    --border: var(--gray-200);
    --primary: var(--navy);
    --primary-hover: var(--navy-light);
    --secondary: var(--gray-100);
    --muted: var(--gray-500);
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-base: 1rem;
    --line-height-base: 1.6;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Border radius */
    --radius: 0.75rem;
    --radius-sm: 0.5rem;
    --radius-lg: 1rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-smooth: 300ms cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    color: var(--foreground);
    background-color: var(--background);
    font-feature-settings: 'cv02', 'cv03', 'cv04', 'cv11';
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
    color: var(--foreground);
}

h1 { font-size: 2.25rem; }
h2 { font-size: 1.875rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.125rem; }
h6 { font-size: 1rem; }

p {
    margin-bottom: var(--spacing-md);
    color: var(--muted);
}

/* Container */
.container {
    max-width: 1120px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

@media (max-width: 768px) {
    .container {
        padding: 0 var(--spacing-md);
    }
}

/* Header */
.header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    padding: var(--spacing-md) 0;
}

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

.logo h1 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0;
}

.logo .subtitle {
    font-size: 0.875rem;
    color: var(--muted);
    margin-bottom: 0;
}

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

@media (max-width: 768px) {
    .logo .subtitle {
        display: none;
    }
    
    .nav {
        gap: var(--spacing-sm);
    }
    
    .btn-text {
        display: none;
    }
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: 0.875rem;
    font-weight: 500;
    text-decoration: none;
    border-radius: var(--radius);
    border: 1px solid transparent;
    transition: all var(--transition-smooth);
    cursor: pointer;
    white-space: nowrap;
}

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

.btn-primary:hover {
    background-color: var(--primary-hover);
    box-shadow: var(--shadow-lg);
    transform: translateY(-1px);
}

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

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

.btn-lg {
    padding: var(--spacing-lg) var(--spacing-xl);
    font-size: var(--font-size-base);
}

.btn-xl {
    padding: var(--spacing-xl) var(--spacing-2xl);
    font-size: 1.125rem;
}

.btn-full {
    width: 100%;
}

.btn-disabled {
    opacity: 0.5;
    cursor: not-allowed;
    pointer-events: auto;
}

.btn-disabled:hover {
    opacity: 0.6;
    background-color: rgba(0, 0, 0, 0.05);
}
/* Hero Section */
.hero {
    padding: var(--spacing-3xl) 0;
    background: linear-gradient(135deg, var(--background) 0%, var(--gray-50) 50%, var(--background) 100%);
}

.hero-content {
    text-align: center;
    max-width: 900px;
    margin: 0 auto;
}

.hero-title {
    font-size: 3rem;
    font-weight: 600;
    margin-bottom: var(--spacing-lg);
    line-height: 1.1;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--muted);
    margin-bottom: var(--spacing-2xl);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.keywords {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-2xl);
}

.keyword-tag {
    display: inline-flex;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--secondary);
    color: var(--foreground);
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: 9999px;
    border: 1px solid var(--border);
}

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

@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .hero-cta {
        flex-direction: column;
        align-items: center;
    }
}

/* Sections */
.section {
    padding: var(--spacing-3xl) 0;
}

.section-alt {
    background-color: var(--gray-50);
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--muted);
    margin-bottom: 0;
}

/* Projects */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-xl);
}

.project-card {
    background: var(--card);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
    overflow: hidden;
    transition: all var(--transition-smooth);
    cursor: pointer;
}

.project-card:hover {
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
    transform: translateY(-4px);
}

.project-image {
    position: relative;
    overflow: hidden;
    height: 200px;
}

.project-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-smooth);
}

.project-card:hover .project-image img {
    transform: scale(1.05);
}

.project-content {
    padding: var(--spacing-lg);
}

.project-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    line-height: 1.3;
}

.project-summary {
    color: var(--muted);
    margin-bottom: var(--spacing-lg);
}

.project-highlights {
    list-style: none;
    margin-bottom: var(--spacing-lg);
}

.project-highlights li {
    position: relative;
    padding-left: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
    font-size: 0.875rem;
    color: var(--muted);
}

.project-highlights li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0.6rem;
    width: 6px;
    height: 6px;
    background-color: var(--primary);
    border-radius: 50%;
}

@media (max-width: 768px) {
    .projects-grid {
        grid-template-columns: 1fr;
    }
}

/* Timeline */
.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 2rem;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--border);
}

.timeline-item {
    position: relative;
    margin-bottom: var(--spacing-xl);
    padding-left: var(--spacing-3xl);
}

.timeline-marker {
    position: absolute;
    left: calc(2% + 0.57rem);
    top: 0.5rem;
    width: 1rem;
    height: 1rem;
    background: var(--primary);
    border-radius: 50%;
    border: 3px solid var(--background);
}

.timeline-content {
    background: var(--card);
    padding: var(--spacing-lg);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition-smooth);
}

.timeline-content:hover {
    box-shadow: var(--shadow-md);
}

.timeline-year {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--secondary);
    color: var(--foreground);
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: 9999px;
    border: 1px solid var(--border);
    margin-bottom: var(--spacing-md);
}

.timeline-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.timeline-org {
    color: var(--primary);
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
}

.timeline-desc {
    color: var(--muted);
    margin-bottom: var(--spacing-md);
}

.timeline-type {
    display: inline-block;
    padding: 2px var(--spacing-sm);
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: var(--radius-sm);
    border: 1px solid;
}

.type-internship {
    background: #EBF8FF;
    color: #2B6CB0;
    border-color: #BEE3F8;
}

.type-project {
    background: #F0FDF4;
    color: #15803D;
    border-color: #BBF7D0;
}

.type-research {
    background: #FAF5FF;
    color: #7C3AED;
    border-color: #E9D5FF;
}

.type-education {
    background: #FFFBEB;
    color: #D97706;
    border-color: #FED7AA;
}

@media (max-width: 768px) {
    .timeline::before {
        left: 1rem;
    }
    
    .timeline-item {
        padding-left: var(--spacing-xl);
    }
    
    .timeline-marker {
        left: 0.75rem;
    }
}

/* Skills */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

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

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

.skill-icon {
    width: 3rem;
    height: 3rem;
    background: rgba(13, 27, 42, 0.1);
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-md);
    transition: background-color var(--transition-smooth);
}

.skill-category:hover .skill-icon {
    background: rgba(13, 27, 42, 0.2);
}

.skill-icon i {
    font-size: 1.5rem;
    color: var(--primary);
}

.skill-category h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.skill-desc {
    font-size: 0.875rem;
    color: var(--muted);
    margin-bottom: var(--spacing-md);
}

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

.skill-list li {
    position: relative;
    padding-left: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--foreground);
}

.skill-list li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0.6rem;
    width: 6px;
    height: 6px;
    background-color: var(--primary);
    border-radius: 50%;
}

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

.interest-tag {
    display: inline-flex;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--secondary);
    color: var(--foreground);
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: 9999px;
    border: 1px solid var(--border);
    transition: all var(--transition-fast);
}

.interest-tag:hover {
    background-color: var(--border);
}

/* About */
.about-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.about-text {
    margin-bottom: var(--spacing-2xl);
    text-align: left;
}

.about-text p {
    font-size: 1.125rem;
    line-height: 1.7;
    margin-bottom: var(--spacing-lg);
}

.about-cta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    justify-content: center;
    margin-bottom: var(--spacing-xl);
}

.about-social {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
}

@media (max-width: 768px) {
    .about-cta,
    .about-social {
        flex-direction: column;
        align-items: center;
    }
}

/* Contact */
.contact-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.contact-primary {
    margin-top:0.5rem;
    margin-bottom: var(--spacing-2xl);
}

.contact-info {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.contact-item {
    background: var(--card);
    padding: var(--spacing-lg);
    border-radius: var(--radius);
    border: 1px solid var(--border);
}

.contact-icon {
    width: 3rem;
    height: 3rem;
    background: rgba(13, 27, 42, 0.1);
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto var(--spacing-md);
}

.contact-icon i {
    font-size: 1.5rem;
    color: var(--primary);
}

.contact-item h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.contact-item p {
    color: var(--muted);
    margin-bottom: 0;
}

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

@media (max-width: 768px) {
    .contact-social {
        flex-direction: column;
        align-items: center;
    }
}

/* Footer */
.footer {
    background-color: var(--background);
    border-top: 1px solid var(--border);
    padding: var(--spacing-xl) 0;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.footer-copyright {
    font-size: 0.875rem;
    color: var(--muted);
}

.footer-social {
    display: flex;
    gap: var(--spacing-md);
}

.footer-social a {
    color: var(--muted);
    font-size: 1.25rem;
    transition: color var(--transition-fast);
}

.footer-social a:hover {
    color: var(--foreground);
}

.footer-tagline {
    text-align: center;
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border);
    font-size: 0.75rem;
    color: var(--muted);
}

@media (max-width: 768px) {
    .footer-content {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }
}

/* Animations */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 0.6s ease-out forwards;
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Utility Classes */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}