/* Design Tokens / Variables */
:root {
    --bg-color: #fafafa;
    --card-bg: #ffffff;
    --text-primary: #111111;
    --text-muted: #555555;
    --accent-color: #2c3e50; /* Deep elegant slate charcoal */
    --border-color: #e5e5e5;
    --max-width: 1040px;
    --font-stack: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

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

html {
    scroll-behavior: smooth;
    background-color: var(--bg-color);
    font-family: var(--font-stack);
    color: var(--text-primary);
    line-height: 1.6;
}

/* Navigation Layout */
.navbar {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: rgba(250, 250, 250, 0.85);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 1.25rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-weight: 500;
    font-size: 1.1rem;
    text-decoration: none;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-left: 2rem;
    transition: color 0.2s ease;
}

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

.nav-links .btn-contact {
    background-color: var(--text-primary);
    color: var(--bg-color);
    padding: 0.5rem 1rem;
    border-radius: 4px;
}

.nav-links .btn-contact:hover {
    background-color: var(--accent-color);
    color: #ffffff;
}

/* Main Layout Wrapper */
.content-wrapper {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 4rem 2rem;
}

.divider {
    border: 0;
    height: 1px;
    background: var(--border-color);
    margin: 4rem 0;
}

/* Hero Section */
.hero-section {
    padding: 4rem 0 2rem 0;
    max-width: 800px;
}

.hero-title {
    font-size: 2.75rem;
    font-weight: 400;
    line-height: 1.25;
    letter-spacing: -0.03em;
    margin-bottom: 1.5rem;
}

.hero-subtitle {
    font-size: 1.2rem;
    color: var(--text-muted);
    font-weight: 300;
}

/* Split Grid Sections (Expertise & Credentials) */
.grid-section, .timeline-section {
    display: grid;
    grid-template-columns: 250px 1fr;
    gap: 2rem;
}

.section-label {
    text-transform: uppercase;
    font-size: 0.8rem;
    letter-spacing: 0.1em;
    color: var(--text-muted);
    font-weight: 600;
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
    gap: 1.5rem;
}

.skill-card {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 6px;
    border: 1px solid var(--border-color);
}

.skill-card h3 {
    font-size: 1.1rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.skill-card p {
    font-size: 0.9rem;
    color: var(--text-muted);
}

/* Experience / Timeline Section */
.timeline-container {
    display: flex;
    flex-direction: column;
    gap: 2.5rem;
}

.timeline-item {
    display: grid;
    grid-template-columns: 250px 1fr;
    gap: 1rem;
}

.time-meta h4 {
    font-size: 1rem;
    font-weight: 500;
}

.date-range {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.role-location {
    font-weight: 500;
    color: var(--accent-color);
    margin-bottom: 0.5rem;
}

.time-content p {
    font-size: 0.95rem;
    color: var(--text-muted);
}

/* Credentials Block Layout */
.credentials-container {
    display: flex;
    flex-direction: column;
    gap: 3rem;
}

.cred-type {
    display: inline-block;
    font-size: 0.75rem;
    text-transform: uppercase;
    background: var(--border-color);
    padding: 0.2rem 0.6rem;
    border-radius: 3px;
    margin-bottom: 0.75rem;
    font-weight: 500;
}

.institution {
    font-weight: 500;
    margin-bottom: 0.25rem;
}

.academic-meta {
    font-size: 0.95rem;
    color: var(--text-muted);
}

.cert-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.cert-list li strong {
    display: block;
    font-size: 1rem;
    font-weight: 500;
}

.cert-list li span {
    font-size: 0.95rem;
    color: var(--text-muted);
}

/* Footer Styling */
.site-footer {
    border-top: 1px solid var(--border-color);
    text-align: center;
    padding: 4rem 2rem;
    font-size: 0.9rem;
    color: var(--text-muted);
    background: #ffffff;
}

.footer-email {
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    display: inline-block;
    margin-top: 0.5rem;
}

/* Mobile Responsiveness Rules */
@media (max-width: 768px) {
    .grid-section, .timeline-section, .timeline-item {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    .hero-title {
        font-size: 2rem;
    }
    .nav-links a {
        margin-left: 1rem;
    }
}