/* ===== CSS VARIABLES ===== */
:root {
    /* Color Palette */
    --primary-color: #4a9eff;
    --primary-hover: #3a8eef;
    --secondary-color: #2962ff;
    --dark-color: #0078ff;
    --light-color: #6ab3ff;
    
    /* Background Colors */
    --bg-color: #121212;
    --bg-accent: #1e1e1e;
    --bg-light: #2d2d2d;
    --bg-card: rgba(45, 45, 45, 0.95);
    
    /* Text Colors */
    --text-color: #e0e0e0;
    --text-light: #a0a0a0;
    --text-muted: #808080;
    
    /* Border & Shadow */
    --border-color: #333333;
    --border-radius: 8px;
    --border-radius-large: 12px;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-hover: 0 8px 25px rgba(0, 0, 0, 0.4);
    
    /* Transitions */
    --transition: all 0.3s ease;
    --transition-fast: all 0.15s ease;
    --transition-slow: all 0.5s ease;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-xxl: 4rem;
    
    /* Typography */
    --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;
    
    /* Z-index */
    --z-header: 1000;
    --z-modal: 1100;
    --z-tooltip: 1200;
}

/* ===== RESET & BASE STYLES ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
    font-size: var(--font-size-base);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: opacity var(--transition);
}

body.loaded {
    opacity: 1;
}

body:not(.loaded) {
    opacity: 0;
}

/* ===== TYPOGRAPHY ===== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
    margin-bottom: var(--spacing-sm);
}

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
h3 { font-size: var(--font-size-3xl); }
h4 { font-size: var(--font-size-2xl); }
h5 { font-size: var(--font-size-xl); }
h6 { font-size: var(--font-size-lg); }

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

/* ===== LINKS ===== */
a {
    text-decoration: none;
    color: var(--primary-color);
    transition: var(--transition);
}

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

a:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* ===== LAYOUT ===== */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* ===== HEADER ===== */
header {
    background-color: var(--bg-color);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow);
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: var(--z-header);
    transition: var(--transition);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg) 0;
}

.logo {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--text-color);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    width: 48px;
    height: 48px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.logo::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: var(--transition);
}

.logo:hover::before {
    left: 100%;
}

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

.nav-links a {
    color: var(--text-color);
    font-weight: 500;
    transition: var(--transition);
    position: relative;
    padding: var(--spacing-xs) 0;
}

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

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

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

/* ===== MOBILE MENU ===== */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    justify-content: space-between;
    width: 30px;
    height: 24px;
    cursor: pointer;
    background: none;
    border: none;
    padding: 0;
    transition: var(--transition);
}

.mobile-menu-btn span {
    height: 3px;
    width: 100%;
    background-color: var(--text-color);
    transition: var(--transition);
    border-radius: 2px;
}

.mobile-menu-btn:hover span {
    background-color: var(--primary-color);
}

/* ===== HERO SECTION ===== */
#hero {
    padding: 160px 0 100px;
    background: linear-gradient(135deg, var(--bg-color) 0%, var(--bg-accent) 100%);
    position: relative;
    overflow: hidden;
}

#hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 20% 80%, rgba(74, 158, 255, 0.1) 0%, transparent 50%),
                radial-gradient(circle at 80% 20%, rgba(41, 98, 255, 0.1) 0%, transparent 50%);
    pointer-events: none;
}

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

.profile-img {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    object-fit: cover;
    border: 4px solid var(--primary-color);
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--shadow);
    transition: var(--transition);
    position: relative;
}

.profile-img:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-hover);
}

.profile-img::before {
    content: '';
    position: absolute;
    top: -8px;
    left: -8px;
    right: -8px;
    bottom: -8px;
    border: 2px solid transparent;
    border-radius: 50%;
    background: linear-gradient(45deg, var(--primary-color), var(--secondary-color)) border-box;
    -webkit-mask: linear-gradient(#fff 0 0) padding-box, linear-gradient(#fff 0 0);
    -webkit-mask-composite: destination-out;
    mask: linear-gradient(#fff 0 0) padding-box, linear-gradient(#fff 0 0);
    mask-composite: exclude;
    opacity: 0;
    transition: var(--transition);
}

.profile-img:hover::before {
    opacity: 1;
}

.hero-content h1 {
    font-size: var(--font-size-5xl);
    margin-bottom: var(--spacing-sm);
    color: var(--primary-color);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-content h2 {
    font-size: var(--font-size-2xl);
    font-weight: 500;
    margin-bottom: var(--spacing-lg);
    color: var(--text-color);
}

.hero-content p {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
    color: var(--text-light);
    line-height: 1.7;
}

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

/* ===== BUTTONS ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md) var(--spacing-xl);
    font-weight: 600;
    border-radius: 50px;
    transition: var(--transition);
    text-align: center;
    min-height: 48px;
    position: relative;
    overflow: hidden;
    border: none;
    cursor: pointer;
    font-size: var(--font-size-base);
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: var(--transition);
}

.btn:hover::before {
    left: 100%;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    box-shadow: var(--shadow);
}

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

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

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

/* ===== SECTION STYLES ===== */
section {
    padding: var(--spacing-xxl) 0;
}

.section-title {
    font-size: var(--font-size-3xl);
    text-align: center;
    margin-bottom: var(--spacing-xxl);
    color: var(--text-color);
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -15px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border-radius: 2px;
}

/* ===== ABOUT SECTION ===== */
#about {
    background-color: var(--bg-accent);
}

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

.about-text p {
    font-size: var(--font-size-lg);
    line-height: 1.8;
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

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

.timeline::before {
    content: '';
    position: absolute;
    left: 50%;
    top: 0;
    bottom: 0;
    width: 2px;
    background: linear-gradient(to bottom, var(--primary-color), var(--secondary-color));
    transform: translateX(-50%);
}

.timeline-item {
    position: relative;
    margin-bottom: var(--spacing-xl);
    padding-left: 50%;
}

.timeline-item:nth-child(even) {
    padding-left: 0;
    padding-right: 50%;
}

.timeline-dot {
    position: absolute;
    left: -6px;
    top: 20px;
    width: 12px;
    height: 12px;
    background: var(--primary-color);
    border-radius: 50%;
    border: 3px solid var(--bg-color);
    box-shadow: var(--shadow);
}

.timeline-item:nth-child(even) .timeline-dot {
    left: auto;
    right: -6px;
}

.timeline-date {
    position: absolute;
    top: 0;
    left: -200px;
    background: var(--bg-card);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius);
    font-weight: 600;
    color: var(--primary-color);
    white-space: nowrap;
    box-shadow: var(--shadow);
}

.timeline-item:nth-child(even) .timeline-date {
    left: auto;
    right: -200px;
}

.timeline-content {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius-large);
    box-shadow: var(--shadow);
    transition: var(--transition);
    border-left: 4px solid var(--primary-color);
}

.timeline-item:nth-child(even) .timeline-content {
    border-left: none;
    border-right: 4px solid var(--primary-color);
}

.timeline-content:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

.timeline-content h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-xs);
}

.timeline-content h4 {
    color: var(--text-light);
    font-weight: 500;
    margin-bottom: var(--spacing-md);
}

.timeline-content ul {
    list-style: none;
}

.timeline-content li {
    margin-bottom: var(--spacing-sm);
    padding-left: var(--spacing-md);
    position: relative;
    line-height: 1.6;
}

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

/* ===== EDUCATION SECTION ===== */
.education-items {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    max-width: 800px;
    margin: 0 auto;
}

.education-item {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius-large);
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 1px solid var(--border-color);
    text-align: center;
}

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

.education-item h3.school-name {
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
    font-size: var(--font-size-xl);
}

.education-item h4 {
    color: var(--text-color);
    margin-bottom: var(--spacing-sm);
    font-weight: 500;
}

.education-item time {
    color: var(--text-light);
    font-size: var(--font-size-sm);
}

/* ===== SKILLS SECTION ===== */
.skills-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-xl);
    max-width: 1000px;
    margin: 0 auto;
}

.skills-category {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius-large);
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

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

.certification-container {
    grid-column: 1 / -1;
    text-align: center;
}

.skills-category h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
    text-align: center;
    font-size: var(--font-size-xl);
}

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

.skill-tag {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: 20px;
    font-size: var(--font-size-sm);
    font-weight: 500;
    transition: var(--transition);
    cursor: default;
}

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

.certification-list {
    justify-content: center;
}

.certification {
    background: var(--bg-light);
    padding: var(--spacing-md);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
}

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

.certification-name {
    font-weight: 600;
    color: var(--text-color);
}

.certification-year {
    color: var(--text-light);
    font-size: var(--font-size-sm);
}

/* ===== CONTACT SECTION ===== */
#contact {
    background-color: var(--bg-accent);
}

.contact-container {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

.contact-info {
    margin-bottom: var(--spacing-xl);
}

.contact-item {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-md);
    background: var(--bg-card);
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.contact-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.contact-item i {
    font-size: var(--font-size-xl);
    color: var(--primary-color);
}

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

.social-links a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background: var(--bg-card);
    border-radius: 50%;
    transition: var(--transition);
    border: 2px solid transparent;
}

.social-links a:hover {
    background: var(--primary-color);
    transform: translateY(-3px);
    box-shadow: var(--shadow);
}

.social-links a:hover i {
    color: white;
}

.social-links i {
    font-size: var(--font-size-xl);
    color: var(--primary-color);
    transition: var(--transition);
}

/* ===== FOOTER ===== */
footer {
    background-color: var(--bg-color);
    padding: var(--spacing-xl) 0;
    text-align: center;
    color: var(--text-light);
    border-top: 1px solid var(--border-color);
}

/* ===== RESPONSIVE DESIGN ===== */
@media screen and (max-width: 768px) {
    .nav-links {
        position: fixed;
        top: 80px;
        left: 0;
        width: 100%;
        height: 0;
        overflow: hidden;
        flex-direction: column;
        align-items: center;
        background-color: var(--bg-color);
        transition: var(--transition);
        box-shadow: var(--shadow);
        gap: 0;
    }

    .nav-links.active {
        height: 300px;
        padding: var(--spacing-lg) 0;
    }

    .nav-links li {
        margin: var(--spacing-sm) 0;
    }

    .mobile-menu-btn {
        display: flex;
    }

    .hero-content h1 {
        font-size: var(--font-size-4xl);
    }

    .hero-content h2 {
        font-size: var(--font-size-xl);
    }

    .hero-btns {
        flex-direction: column;
        gap: var(--spacing-sm);
    }

    .btn {
        width: 100%;
        max-width: 300px;
    }

    section {
        padding: var(--spacing-xl) 0;
    }

    .timeline::before {
        left: 30px;
    }

    .timeline-item {
        padding-left: 70px;
    }

    .timeline-item:nth-child(even) {
        padding-left: 70px;
        padding-right: 0;
    }

    .timeline-dot {
        left: 26px;
    }

    .timeline-item:nth-child(even) .timeline-dot {
        left: 26px;
        right: auto;
    }

    .timeline-date {
        left: 70px;
        right: auto;
        top: -10px;
    }

    .timeline-item:nth-child(even) .timeline-date {
        left: 70px;
        right: auto;
    }

    .timeline-content {
        border-left: 4px solid var(--primary-color);
        border-right: none;
    }

    .timeline-item:nth-child(even) .timeline-content {
        border-left: 4px solid var(--primary-color);
        border-right: none;
    }
    
    .education-items {
        gap: var(--spacing-md);
    }

    .education-item {
        margin-bottom: 0;
    }

    .skills-container {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }
}

@media screen and (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-md);
    }

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

    .hero-content h2 {
        font-size: var(--font-size-lg);
    }

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

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

    .timeline::before {
        left: 20px;
    }

    .timeline-item {
        padding-left: 50px;
    }

    .timeline-item:nth-child(even) {
        padding-left: 50px;
    }

    .timeline-dot {
        left: 16px;
    }

    .timeline-item:nth-child(even) .timeline-dot {
        left: 16px;
    }

    .timeline-content {
        padding: var(--spacing-md);
    }

    .timeline-date {
        left: 50px;
        font-size: var(--font-size-sm);
        padding: var(--spacing-xs) var(--spacing-sm);
    }

    .timeline-item:nth-child(even) .timeline-date {
        left: 50px;
    }

    .education-items {
        gap: var(--spacing-sm);
    }
    
    #education {
        padding: var(--spacing-lg) 0 var(--spacing-md);
    }
    
    #education .container {
        max-width: 100%;
        padding: 0 var(--spacing-md);
    }
    
    .education-item {
        background-color: var(--bg-card);
        padding: var(--spacing-md);
    }
    
    .education-item h3.school-name {
        font-size: var(--font-size-base);
        margin-bottom: var(--spacing-xs);
        line-height: 1.3;
    }
    
    .education-item h4 {
        font-size: var(--font-size-sm);
        margin-bottom: var(--spacing-xs);
        line-height: 1.3;
    }
    
    .education-item time {
        font-size: var(--font-size-xs);
        line-height: 1.3;
    }

    #education .section-title {
        margin-bottom: var(--spacing-lg);
    }

    .skills-category {
        padding: var(--spacing-md);
    }

    .contact-item {
        flex-direction: column;
        gap: var(--spacing-sm);
        text-align: center;
    }
}

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

/* ===== FOCUS VISIBILITY ===== */
*:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* ===== PRINT STYLES ===== */
@media print {
    header,
    .mobile-menu-btn,
    .hero-btns,
    .social-links {
        display: none;
    }
    
    body {
        background: white;
        color: black;
    }
    
    section {
        padding: 20px 0;
        page-break-inside: avoid;
    }
    
    .timeline::before {
        display: none;
    }
    
    .timeline-item {
        padding-left: 0;
        border-left: 3px solid var(--primary-color);
        padding-left: 20px;
    }
}