/* ===================================
   CSS VARIABLES & THEME SYSTEM
   =================================== */

:root {
    /* Color Palette - Light Theme */
    --color-primary: #1e3a8a;        /* Deep indigo - professional, distinctive */
    --color-primary-light: #3b82f6;
    --color-primary-dark: #1e293b;
    --color-accent: #d97706;          /* Warm amber accent */
    --color-accent-light: #fbbf24;
    
    --color-bg: #fafaf9;              /* Warm off-white */
    --color-surface: #ffffff;
    --color-surface-elevated: #f5f5f4;
    
    --color-text-primary: #1c1917;
    --color-text-secondary: #57534e;
    --color-text-tertiary: #78716c;
    --color-border: #e7e5e4;
    --color-border-light: #f5f5f4;
    
    /* Typography */
    --font-display: 'Playfair Display', Georgia, serif;  /* Distinctive editorial font */
    --font-body: 'Source Sans 3', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    
    --font-weight-light: 300;
    --font-weight-normal: 400;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    --font-weight-extrabold: 800;
    
    /* Spacing Scale */
    --space-xs: 0.5rem;
    --space-sm: 0.75rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    --space-4xl: 6rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    
    /* 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 ease;
    --transition-base: 250ms ease;
    --transition-slow: 400ms ease;
    
    /* Layout */
    --max-width: 1200px;
    --nav-height: 70px;
}

/* Dark Theme */
body[data-theme="dark"] {
    --color-primary: #60a5fa;
    --color-primary-light: #93c5fd;
    --color-primary-dark: #2563eb;
    --color-accent: #fbbf24;
    --color-accent-light: #fcd34d;
    
    --color-bg: #0f172a;
    --color-surface: #1e293b;
    --color-surface-elevated: #334155;
    
    --color-text-primary: #f1f5f9;
    --color-text-secondary: #cbd5e1;
    --color-text-tertiary: #94a3b8;
    --color-border: #334155;
    --color-border-light: #1e293b;
    
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 10px 10px -5px rgba(0, 0, 0, 0.3);
}

/* ===================================
   RESET & BASE STYLES
   =================================== */

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-body);
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-bg);
    transition: background-color var(--transition-base), color var(--transition-base);
}

/* ===================================
   LOADING SCREEN
   =================================== */

.loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--color-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    transition: opacity var(--transition-slow), visibility var(--transition-slow);
}

.loading-screen.hidden {
    opacity: 0;
    visibility: hidden;
}

.loader {
    width: 48px;
    height: 48px;
    border: 3px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ===================================
   NAVIGATION
   =================================== */

.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    background-color: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
    transition: all var(--transition-base);
}

body[data-theme="dark"] .nav {
    background-color: rgba(15, 23, 42, 0.8);
}

.nav.scrolled {
    box-shadow: var(--shadow-md);
}

.nav-container {
    max-width: var(--max-width);
    height: 100%;
    margin: 0 auto;
    padding: 0 var(--space-lg);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-brand {
    display: flex;
    align-items: center;
}

.nav-initials {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
    letter-spacing: -0.02em;
}

.nav-controls {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.btn-control {
    width: 44px;
    height: 44px;
    border: 1px solid var(--color-border);
    background-color: var(--color-surface);
    border-radius: var(--radius-md);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    color: var(--color-text-secondary);
}

.btn-control:hover {
    background-color: var(--color-surface-elevated);
    border-color: var(--color-primary);
    color: var(--color-primary);
    transform: translateY(-2px);
}

.btn-lang {
    font-family: var(--font-body);
    font-size: 0.875rem;
    font-weight: var(--font-weight-semibold);
    position: relative;
}

.lang-text {
    position: absolute;
    transition: opacity var(--transition-fast);
}

.lang-text[data-lang="en"] {
    opacity: 1;
}

.lang-text[data-lang="ro"] {
    opacity: 0;
}

body[data-lang="ro"] .lang-text[data-lang="en"] {
    opacity: 0;
}

body[data-lang="ro"] .lang-text[data-lang="ro"] {
    opacity: 1;
}

.btn-theme svg {
    width: 20px;
    height: 20px;
    stroke-width: 2;
}

.icon-sun {
    display: block;
}

.icon-moon {
    display: none;
}

body[data-theme="dark"] .icon-sun {
    display: none;
}

body[data-theme="dark"] .icon-moon {
    display: block;
}

/* ===================================
   LAYOUT & CONTAINERS
   =================================== */

.main {
    margin-top: var(--nav-height);
}

.section {
    padding: var(--space-4xl) 0;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

.section-title {
    font-family: var(--font-display);
    font-size: 2.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-2xl);
    letter-spacing: -0.02em;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 0;
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
    border-radius: 2px;
}

/* ===================================
   HERO SECTION
   =================================== */

.hero {
    min-height: calc(100vh - var(--nav-height));
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero-decoration {
    position: absolute;
    top: -10%;
    right: -10%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(30, 58, 138, 0.05) 0%, transparent 70%);
    border-radius: 50%;
    pointer-events: none;
}

body[data-theme="dark"] .hero-decoration {
    background: radial-gradient(circle, rgba(96, 165, 250, 0.08) 0%, transparent 70%);
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 900px;
}

.hero-greeting {
    font-size: 1rem;
    font-weight: var(--font-weight-semibold);
    color: var(--color-primary);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: var(--space-md);
}

.hero-name {
    font-family: var(--font-display);
    font-size: clamp(2.5rem, 6vw, 4.5rem);
    font-weight: var(--font-weight-extrabold);
    color: var(--color-text-primary);
    line-height: 1.1;
    margin-bottom: var(--space-lg);
    letter-spacing: -0.02em;
}

.hero-headline {
    font-size: clamp(1.25rem, 3vw, 1.75rem);
    font-weight: var(--font-weight-semibold);
    color: var(--color-text-secondary);
    line-height: 1.4;
    margin-bottom: var(--space-md);
}

.hero-subheadline {
    font-size: 1.125rem;
    color: var(--color-text-tertiary);
    line-height: 1.6;
    margin-bottom: var(--space-2xl);
    max-width: 700px;
}

.hero-cta {
    display: flex;
    gap: var(--space-md);
    flex-wrap: wrap;
}

/* ===================================
   BUTTONS
   =================================== */

.btn {
    display: inline-flex;
    align-items: center;
    padding: var(--space-md) var(--space-xl);
    font-family: var(--font-body);
    font-size: 1rem;
    font-weight: var(--font-weight-semibold);
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
    cursor: pointer;
    border: none;
}

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

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

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

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

/* ===================================
   ABOUT SECTION
   =================================== */

.about {
    background-color: var(--color-surface);
}

.about-content {
    max-width: 900px;
}

.about-text {
    font-size: 1.125rem;
    line-height: 1.8;
    color: var(--color-text-secondary);
}

/* ===================================
   SKILLS SECTION
   =================================== */

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

.skill-category {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    transition: all var(--transition-base);
}

.skill-category:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
}

.skill-category-name {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-lg);
}

.skill-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.skill-item {
    font-size: 1rem;
    color: var(--color-text-secondary);
    padding-left: var(--space-md);
    position: relative;
}

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

/* ===================================
   EXPERIENCE SECTION (TIMELINE)
   =================================== */

.experience {
    background-color: var(--color-surface);
}

.timeline {
    position: relative;
    padding-left: var(--space-2xl);
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 2px;
    background: linear-gradient(180deg, var(--color-primary), var(--color-accent));
}

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

.timeline-item::before {
    content: '';
    position: absolute;
    left: calc(-1 * var(--space-2xl) - 6px);
    top: 8px;
    width: 14px;
    height: 14px;
    background-color: var(--color-primary);
    border: 3px solid var(--color-bg);
    border-radius: 50%;
    box-shadow: 0 0 0 4px var(--color-surface);
}

.timeline-item:hover::before {
    background-color: var(--color-accent);
    transform: scale(1.2);
}

.timeline-header {
    margin-bottom: var(--space-md);
}

.timeline-company {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-xs);
}

.timeline-title {
    font-size: 1.125rem;
    font-weight: var(--font-weight-semibold);
    color: var(--color-primary);
    margin-bottom: var(--space-xs);
}

.timeline-meta {
    display: flex;
    gap: var(--space-lg);
    flex-wrap: wrap;
    font-size: 0.875rem;
    color: var(--color-text-tertiary);
    margin-bottom: var(--space-md);
}

.timeline-period,
.timeline-location {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
}

.timeline-description {
    color: var(--color-text-secondary);
    margin-bottom: var(--space-md);
    font-style: italic;
}

.timeline-achievements {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.timeline-achievements li {
    padding-left: var(--space-md);
    position: relative;
    color: var(--color-text-secondary);
}

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

/* ===================================
   PROJECTS SECTION
   =================================== */

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--space-xl);
}

.project-card {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    transition: all var(--transition-base);
}

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

.project-name {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-md);
}

.project-description {
    color: var(--color-text-secondary);
    margin-bottom: var(--space-md);
    line-height: 1.6;
}

.project-technologies {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-xs);
    margin-bottom: var(--space-md);
}

.project-tech {
    display: inline-block;
    padding: var(--space-xs) var(--space-sm);
    background-color: var(--color-surface-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: var(--font-weight-semibold);
    color: var(--color-primary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.project-highlights {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
}

.project-highlights li {
    padding-left: var(--space-md);
    position: relative;
    color: var(--color-text-secondary);
    font-size: 0.9rem;
}

.project-highlights li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--color-accent);
    font-weight: var(--font-weight-bold);
}

/* ===================================
   EDUCATION SECTION
   =================================== */

.education {
    background-color: var(--color-surface);
}

.education-list {
    display: grid;
    gap: var(--space-xl);
}

.education-item {
    border-left: 3px solid var(--color-primary);
    padding-left: var(--space-xl);
}

.education-degree {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-xs);
}

.education-institution {
    font-size: 1.125rem;
    font-weight: var(--font-weight-semibold);
    color: var(--color-primary);
    margin-bottom: var(--space-xs);
}

.education-period {
    font-size: 0.875rem;
    color: var(--color-text-tertiary);
    margin-bottom: var(--space-sm);
}

.education-description {
    color: var(--color-text-secondary);
}

/* ===================================
   CREDENTIALS (CERTIFICATIONS & LANGUAGES)
   =================================== */

.credentials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-3xl);
}

.credentials-title {
    font-family: var(--font-display);
    font-size: 1.75rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-lg);
}

.credentials-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.credential-item {
    padding: var(--space-lg);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
}

.credential-item:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-sm);
}

.credential-name {
    font-size: 1.125rem;
    font-weight: var(--font-weight-semibold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-xs);
}

.credential-issuer,
.credential-level {
    font-size: 0.875rem;
    color: var(--color-primary);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--space-xs);
}

.credential-description {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
}

/* ===================================
   CONTACT SECTION
   =================================== */

.contact {
    background-color: var(--color-surface);
}

.contact-content {
    max-width: 700px;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.contact-item {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    font-size: 1.125rem;
}

.contact-icon {
    width: 24px;
    height: 24px;
    color: var(--color-primary);
    flex-shrink: 0;
}

.contact-item a {
    color: var(--color-text-secondary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

/* ===================================
   FOOTER
   =================================== */

.footer {
    padding: var(--space-2xl) 0;
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.footer-text {
    color: var(--color-text-secondary);
    font-size: 0.875rem;
    margin-bottom: var(--space-xs);
}

.footer-note {
    color: var(--color-text-tertiary);
    font-size: 0.75rem;
    font-style: italic;
}

/* ===================================
   ANIMATIONS
   =================================== */

.fade-in {
    opacity: 0;
    animation: fadeIn var(--transition-slow) forwards;
}

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

.fade-in:nth-child(1) { animation-delay: 0.1s; }
.fade-in:nth-child(2) { animation-delay: 0.2s; }
.fade-in:nth-child(3) { animation-delay: 0.3s; }
.fade-in:nth-child(4) { animation-delay: 0.4s; }
.fade-in:nth-child(5) { animation-delay: 0.5s; }

/* Scroll animations - applied via JS */
.scroll-reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.scroll-reveal.revealed {
    opacity: 1;
    transform: translateY(0);
}

/* ===================================
   RESPONSIVE DESIGN
   =================================== */

@media (max-width: 768px) {
    .section {
        padding: var(--space-2xl) 0;
    }
    
    .container {
        padding: 0 var(--space-md);
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .hero {
        min-height: auto;
        padding: var(--space-3xl) 0;
    }
    
    .hero-cta {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    .skills-grid {
        grid-template-columns: 1fr;
    }
    
    .timeline {
        padding-left: var(--space-lg);
    }
    
    .timeline::before {
        left: 0;
    }
    
    .timeline-item::before {
        left: calc(-1 * var(--space-lg) - 6px);
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .credentials-grid {
        grid-template-columns: 1fr;
    }
    
    .nav-container {
        padding: 0 var(--space-md);
    }
}

@media (max-width: 480px) {
    .hero-name {
        font-size: 2rem;
    }
    
    .hero-headline {
        font-size: 1.125rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
}

/* ===================================
   PRINT STYLES
   =================================== */

@media print {
    .nav,
    .hero-cta,
    .btn-control,
    .loading-screen {
        display: none !important;
    }
    
    .main {
        margin-top: 0;
    }
    
    .section {
        page-break-inside: avoid;
        padding: var(--space-lg) 0;
    }
    
    body {
        background-color: white;
        color: black;
    }
}