/* ===========================
   CSS Variables & Reset
   =========================== */
:root {
    --color-bg: #fafafa;
    --color-surface: #ffffff;
    --color-text: #1a1a1a;
    --color-text-muted: #6b6b6b;
    --color-accent: #2d2d2d;
    --color-border: #e0e0e0;
    --color-hover: #f5f5f5;

    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Courier New', monospace;

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

    --border-radius: 2px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
    font-family: var(--font-sans);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ===========================
   Navigation
   =========================== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: rgba(250, 250, 250, 0.8);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
    padding: var(--spacing-sm) 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 0.875rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    color: var(--color-text);
    text-decoration: none;
    transition: var(--transition);
}

.nav-logo:hover {
    opacity: 0.6;
}

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

.nav-link {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    text-decoration: none;
    position: relative;
    transition: var(--transition);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 1px;
    background-color: var(--color-text);
    transition: var(--transition);
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-text);
}

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

/* ===========================
   Hero Section
   =========================== */
.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: var(--spacing-lg) var(--spacing-md);
    position: relative;
}

.hero-content {
    text-align: center;
    max-width: 800px;
}

.hero-title {
    font-size: clamp(2.5rem, 8vw, 5rem);
    font-weight: 300;
    line-height: 1.2;
    margin-bottom: var(--spacing-sm);
}

.greeting {
    display: block;
    font-size: 0.875rem;
    font-weight: 400;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-xs);
}

.name {
    display: block;
    font-weight: 400;
}

.hero-subtitle {
    font-size: 1.125rem;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-sm);
    font-weight: 300;
}

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

.btn {
    padding: 0.875rem 2rem;
    font-size: 0.875rem;
    text-decoration: none;
    border: 1px solid var(--color-border);
    transition: var(--transition);
    display: inline-block;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    font-weight: 500;
}

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

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

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

.btn-secondary:hover {
    background-color: var(--color-accent);
    color: var(--color-bg);
}

.scroll-indicator {
    position: absolute;
    bottom: var(--spacing-lg);
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
}

.scroll-indicator:hover {
    opacity: 0.6;
}

.scroll-text {
    font-size: 0.75rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--color-text-muted);
}

.scroll-line {
    width: 1px;
    height: 40px;
    background-color: var(--color-border);
    animation: scrollAnimation 2s infinite;
}

@keyframes scrollAnimation {
    0%, 100% { opacity: 0; transform: translateY(0); }
    50% { opacity: 1; transform: translateY(10px); }
}

/* ===========================
   Page Content
   =========================== */
.page-content {
    min-height: 100vh;
    padding: calc(60px + var(--spacing-md)) var(--spacing-md) var(--spacing-md);
}

.container {
    max-width: 1000px;
    margin: 0 auto;
}

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

.page-title {
    font-size: 2.5rem;
    font-weight: 300;
    margin-bottom: var(--spacing-sm);
}

.title-underline {
    width: 60px;
    height: 2px;
    background-color: var(--color-accent);
}

/* ===========================
   About Page
   =========================== */
.about-section {
    margin-bottom: var(--spacing-lg);
}

.about-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
    align-items: start;
}

.about-text {
    padding-top: 0;
}

.section-subtitle {
    font-size: 1.25rem;
    font-weight: 400;
    margin-bottom: var(--spacing-sm);
}

.about-text p {
    margin-bottom: var(--spacing-sm);
    color: var(--color-text-muted);
}

.about-details {
    margin-top: var(--spacing-md);
    display: grid;
    gap: var(--spacing-sm);
}

.detail-item {
    display: grid;
    grid-template-columns: 120px 1fr;
    gap: var(--spacing-sm);
    padding: var(--spacing-xs) 0;
    border-bottom: 1px solid var(--color-border);
}

.detail-label {
    font-size: 0.875rem;
    color: var(--color-text-muted);
}

.detail-value {
    font-size: 0.875rem;
    color: var(--color-text);
}

.link {
    color: var(--color-text);
    text-decoration: none;
    border-bottom: 1px solid var(--color-border);
    transition: var(--transition);
}

.link:hover {
    border-color: var(--color-text);
}

/* ===========================
   Timeline (Experience)
   =========================== */
.timeline {
    position: relative;
    padding-left: var(--spacing-md);
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 1px;
    background-color: var(--color-border);
}

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

.timeline-marker {
    position: absolute;
    left: calc(-1 * var(--spacing-md));
    top: 6px;
    width: 9px;
    height: 9px;
    border-radius: 50%;
    background-color: var(--color-accent);
    transform: translateX(-4px);
}

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

.timeline-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    margin-bottom: var(--spacing-xs);
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.timeline-title {
    font-size: 1.25rem;
    font-weight: 400;
}

.timeline-date {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    font-family: var(--font-mono);
}

.timeline-company {
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-sm);
    font-size: 0.9375rem;
}

.timeline-details {
    list-style: none;
    margin-left: 0;
}

.timeline-details li {
    position: relative;
    padding-left: var(--spacing-sm);
    margin-bottom: var(--spacing-xs);
    color: var(--color-text-muted);
    font-size: 0.9375rem;
}

.timeline-details li::before {
    content: '—';
    position: absolute;
    left: 0;
}

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

.project-card {
    padding: var(--spacing-md);
    border: 1px solid var(--color-border);
    background-color: var(--color-surface);
    transition: var(--transition);
}

.project-card:hover {
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
}

.project-content {
    display: flex;
    flex-direction: column;
}

.project-title {
    font-size: 1.25rem;
    font-weight: 400;
    margin-bottom: var(--spacing-sm);
}

.project-description {
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-sm);
    font-size: 0.9375rem;
}

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

.tag {
    font-size: 0.75rem;
    padding: 0.25rem 0.75rem;
    background-color: var(--color-hover);
    color: var(--color-text-muted);
    border: 1px solid var(--color-border);
    font-family: var(--font-mono);
}

.project-links {
    display: flex;
    gap: var(--spacing-sm);
}

/* ===========================
   Skills
   =========================== */
.skills-section {
    display: grid;
    gap: var(--spacing-md);
}

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

.category-title {
    font-size: 1.5rem;
    font-weight: 300;
    margin-bottom: var(--spacing-md);
}

.skills-list {
    display: grid;
    gap: var(--spacing-md);
}

.skill-item {
    padding: var(--spacing-sm);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
}

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

.skill-name {
    font-size: 0.9375rem;
    font-weight: 500;
}

.skill-level {
    font-size: 0.75rem;
    color: var(--color-text-muted);
    font-family: var(--font-mono);
}

.skill-bar {
    height: 4px;
    background-color: var(--color-hover);
    overflow: hidden;
}

.skill-progress {
    height: 100%;
    background-color: var(--color-accent);
    width: 0;
    transition: width 1s cubic-bezier(0.4, 0, 0.2, 1);
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: var(--spacing-sm);
}

.tool-item {
    padding: var(--spacing-sm);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    text-align: center;
    font-size: 0.875rem;
    transition: var(--transition);
}

.tool-item:hover {
    background-color: var(--color-hover);
}

/* ===========================
   Home Page Sections
   =========================== */
.expertise-section {
    padding: var(--spacing-md) var(--spacing-md);
    background-color: var(--color-bg);
}

.section-title {
    font-size: 2rem;
    font-weight: 300;
    text-align: center;
    margin-bottom: var(--spacing-sm);
}

.expertise-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    max-width: 1200px;
    margin: 0 auto;
}

.expertise-card {
    padding: var(--spacing-md);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    transition: var(--transition);
}

.expertise-card:hover {
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
    transform: translateY(-2px);
}

.expertise-title {
    font-size: 1.125rem;
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
}

.expertise-description {
    font-size: 0.9375rem;
    color: var(--color-text-muted);
    line-height: 1.6;
    margin-bottom: var(--spacing-sm);
}

.expertise-tech {
    font-size: 0.75rem;
    color: var(--color-text-muted);
    font-family: var(--font-mono);
    letter-spacing: 0.05em;
}

.contact-section {
    padding: var(--spacing-md) var(--spacing-md);
    background-color: var(--color-surface);
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.contact-intro {
    font-size: 1rem;
    color: var(--color-text-muted);
    max-width: 600px;
    margin: 0 auto var(--spacing-md);
}

.contact-details {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.contact-link {
    font-size: 1.125rem;
    color: var(--color-text);
    text-decoration: none;
    transition: var(--transition);
}

.contact-link:hover {
    color: var(--color-text-muted);
}

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

/* ===========================
   Responsive Design
   =========================== */
@media (max-width: 768px) {
    .nav-container {
        padding: 0 var(--spacing-sm);
    }

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

    .about-grid,
    .project-card {
        grid-template-columns: 1fr;
    }

    .timeline {
        padding-left: var(--spacing-sm);
    }

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

    .detail-item {
        grid-template-columns: 1fr;
    }
}