:root {
    --bg-color: #0f172a;
    --surface-color: #1e293b;
    --surface-hover: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #38bdf8;
    --accent-hover: #0ea5e9;
    --border-color: #334155;
    
    --font-sans: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 2rem;
    --spacing-xl: 4rem;
    
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-pill: 9999px;
    
    --transition-base: 0.2s ease-in-out;
}

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

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

a {
    color: var(--accent-color);
    text-decoration: none;
    transition: color var(--transition-base);
}

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

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

ul {
    padding-left: 1.25rem;
}

li {
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

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

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.section {
    padding: var(--spacing-xl) 0;
    border-bottom: 1px solid var(--border-color);
}

.section:last-child {
    border-bottom: none;
}

.section__title {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.hero {
    padding: 6rem 0 4rem;
    text-align: center;
    position: relative;
    border-bottom: 1px solid var(--border-color);
}

.hero__cover {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 250px;
    object-fit: cover;
    opacity: 0.15;
    z-index: 0;
    -webkit-mask-image: linear-gradient(to bottom, black 0%, transparent 100%);
    mask-image: linear-gradient(to bottom, black 0%, transparent 100%);
}

.hero__content {
    position: relative;
    z-index: 1;
}

.hero__title {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 800;
    letter-spacing: -0.02em;
    margin-bottom: var(--spacing-sm);
}

.hero__subtitle {
    font-size: clamp(1.25rem, 3vw, 1.5rem);
    color: var(--accent-color);
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
}

.hero__tech-stack {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.5rem; 
    margin-top: 1rem;
    margin-bottom: 2.5rem; 
}

.hero-badge {
    padding: 0.25rem 0.75rem; 
    border-radius: 6px; 
    font-size: 0.85rem; 
    font-weight: 700;
    letter-spacing: 0.5px;
    text-transform: uppercase;
    backdrop-filter: blur(4px);
    cursor: default; 
}

.badge-primary {
    background-color: rgba(56, 189, 248, 0.1); 
    color: var(--accent-color);
    border: 1px solid rgba(56, 189, 248, 0.4); 
}

.badge-secondary {
    background-color: rgba(30, 41, 59, 0.5);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}

.hero__links {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-md);
    list-style: none;
    padding: 0;
}

.btn {
    display: inline-flex;
    align-items: center;
    padding: 0.6rem 1.25rem;
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-pill);
    color: var(--text-primary);
    font-weight: 500;
    font-size: 0.95rem;
    transition: background-color var(--transition-base), border-color var(--transition-base), color var(--transition-base), transform var(--transition-base);
}

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

.grid-2 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-lg);
}

.grid-3 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.node-pipeline {
    display: flex;
    flex-direction: column;
    gap: 10px;
    background: #1e1e1e;
    padding: 20px;
    border-radius: 8px;
    border: 1px solid #333;
    font-family: monospace;
    overflow-x: auto;
}

.node-flow {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px;
    background: #252526;
    border-radius: 6px;
    border: 1px dashed #444;
}

.node-label {
    color: #aaa;
    font-size: 0.85em;
    min-width: 140px;
    font-weight: bold;
}

.node {
    background: #333;
    color: #4CAF50;
    padding: 6px 12px;
    border-radius: 4px;
    border: 1px solid #555;
    white-space: nowrap;
    font-size: 0.9em;
}

.node.output-node {
    color: #ff9800;
    border-color: #ff9800;
}

.node-arrow {
    color: #888;
    font-weight: bold;
}

.tech-feature {
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.tech-feature__title {
    font-size: 1.35rem;
    font-weight: 600;
    color: var(--accent-color);
    margin-bottom: 0.5rem;
}

.tech-feature__content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.card {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: transform var(--transition-base), box-shadow var(--transition-base), border-color var(--transition-base);
    height: 100%;
}

.card:hover {
    border-color: var(--text-secondary);
    transform: translateY(-4px);
    box-shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
}

.card__title {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.card__subtitle {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: var(--spacing-md);
    font-style: italic;
}

.project-card {
    display: flex;
    flex-direction: column;
    overflow: hidden;
    padding: 0;
}

.project-card__image {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-bottom: 1px solid var(--border-color);
    background-color: #000;
}

.project-card__content {
    padding: var(--spacing-lg);
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.project-card__links {
    margin-top: auto;
    padding-top: var(--spacing-md);
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.project-link {
    font-size: 0.9rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.rd-intro {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: var(--spacing-lg);
}

details {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
    overflow: hidden;
    transition: border-color var(--transition-base);
}

details:hover {
    border-color: var(--text-secondary);
}

summary {
    padding: 1.25rem;
    font-weight: 600;
    font-size: 1.1rem;
    cursor: pointer;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
    user-select: none;
}

summary::-webkit-details-marker {
    display: none;
}

summary::after {
    content: "+";
    font-size: 1.5rem;
    color: var(--accent-color);
    transition: transform 0.3s ease;
}

details[open] summary::after {
    transform: rotate(45deg);
}

.details-content {
    padding: 0 1.25rem 1.25rem;
    border-top: 1px solid var(--border-color);
    margin-top: 0.5rem;
    padding-top: 1rem;
}

.skill-group h4 {
    font-size: 1.1rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
    border-bottom: 2px solid var(--surface-color);
    padding-bottom: 0.5rem;
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.tag {
    background-color: var(--surface-color);
    color: var(--accent-color);
    padding: 0.4rem 0.8rem;
    border-radius: var(--radius-pill);
    font-size: 0.9rem;
    font-weight: 500;
    border: 1px solid var(--border-color);
}

.email-btn {
    position: relative;
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
}

.tooltip {
    position: absolute;
    bottom: 130%;
    left: 50%;
    transform: translateX(-50%) translateY(8px);
    background-color: var(--text-primary);
    color: var(--bg-color);
    padding: 0.4rem 0.8rem;
    border-radius: var(--radius-md);
    font-size: 0.8rem;
    font-weight: 600;
    white-space: nowrap;
    pointer-events: none;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.2s cubic-bezier(0.16, 1, 0.3, 1), 
                visibility 0.2s cubic-bezier(0.16, 1, 0.3, 1), 
                transform 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.tooltip::after {
    content: '';
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    border-width: 5px;
    border-style: solid;
    border-color: var(--text-primary) transparent transparent transparent;
}

.tooltip.show {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

button.btn {
    font-family: inherit;
    cursor: pointer;
}

.experience-subtitle {
    margin-top: 0.5rem;
    margin-bottom: 0.2rem;
    color: var(--text-primary);
    font-style: normal;
    font-weight: 600;
}

.experience-date {
    font-size: 0.85rem;
    color: var(--accent-color);
    margin-bottom: 0.75rem;
    font-weight: 500;
}

.project-card__image--top {
    object-position: top;
}

.section--no-border {
    border-bottom: none;
    padding-bottom: 4rem;
}

@media (max-width: 768px) {
    .section {
        padding: 3rem 0;
    }
    .hero {
        padding: 4rem 0 3rem;
    }
}