:root {
    --techslate: #212F3D;      
    --textgray: #2D3748;       
    --linkblue: #2980B9;       
    --lightbg: #F8F9FA;        
    --ytred: #CC0000;          
    --bordergray: #E2E8F0;     
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: 80px; }
body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; color: var(--textgray); line-height: 1.6; background-color: #FFFFFF; padding-top: 60px; }
a { color: var(--linkblue); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--techslate); }

/* --- Sticky Navigation & Mobile Menu --- */
.navbar { position: fixed; top: 0; left: 0; width: 100%; height: 60px; background-color: rgba(33, 47, 61, 0.98); z-index: 1000; border-bottom: 1px solid rgba(255,255,255,0.1); }
.nav-container { max-width: 1050px; margin: 0 auto; height: 100%; display: flex; align-items: center; padding: 0 20px; }
.nav-brand { color: #FFFFFF; font-weight: 700; font-size: 1.1rem; letter-spacing: -0.3px; transition: opacity 0.2s; }
.nav-brand:hover { opacity: 0.8; }

.nav-links { display: flex; gap: 24px; list-style: none; margin-left: auto; margin-right: 30px; }
.nav-links a { color: rgba(255,255,255,0.85); font-size: 0.9rem; font-weight: 600; }
.nav-links a:hover { color: #FFFFFF; }
.menu-toggle { display: none; color: #FFFFFF; font-size: 1.5rem; cursor: pointer; background: none; border: none; }

/* --- Language Switcher --- */
.lang-switch { display: flex; gap: 8px; align-items: center; color: rgba(255,255,255,0.4); font-size: 0.85rem; font-weight: 700; }
.lang-switch a { color: rgba(255,255,255,0.5); transition: color 0.2s; }
.lang-switch a:hover { color: #FFFFFF; }
.lang-switch a.active { color: #3498DB; pointer-events: none; }

/* --- Layout Containers --- */
.container { max-width: 1050px; margin: 0 auto; padding: 0 20px; }
section { padding: 60px 0; border-bottom: 1px solid var(--bordergray); }
.bg-light { background-color: var(--lightbg); }

/* --- Hero Section & Banner --- */
header { background-color: var(--techslate); color: #FFFFFF; padding: 55px 0; }
.hero-layout { display: flex; align-items: center; justify-content: space-between; gap: 40px; }
.hero-text { flex: 1; }
.hero-text h1 { font-size: 2.8rem; font-weight: 800; margin: 0 0 6px 0; letter-spacing: -0.5px; line-height: 1.2; }
.hero-text .subtitle { font-size: 1.15rem; opacity: 0.95; margin: 0 0 8px 0; font-weight: 400; color: #E2E8F0; line-height: 1.5; }
.keyword-strip { font-size: 0.9rem; color: #63B3ED; font-weight: 600; margin-bottom: 22px; letter-spacing: 0.3px; }

.hero-photo-container { flex-shrink: 0; margin: 0; }
.hero-photo { width: 170px; height: 170px; border-radius: 50%; object-fit: cover; border: 3px solid rgba(255, 255, 255, 0.25); box-shadow: 0 8px 24px rgba(0,0,0,0.3); background-color: #ECEFF1; }

.social-links { display: flex; gap: 18px; flex-wrap: wrap; margin: 0 0 20px 0; }
.social-links a { color: #FFFFFF; font-size: 0.95rem; display: inline-flex; align-items: center; gap: 6px; opacity: 0.85; transition: opacity 0.2s, transform 0.2s; }
.social-links a:hover { opacity: 1; color: #3498DB; transform: translateY(-2px); }
.cta-banner { background-color: rgba(41, 128, 185, 0.2); border: 1px solid #3498DB; color: #FFFFFF; padding: 10px 16px; border-radius: 6px; display: inline-block; font-weight: 600; font-size: 0.9rem; margin-bottom: 15px; }
.btn-group { margin: 12px 0 20px 0; display: flex; gap: 10px; flex-wrap: wrap; }

/* --- Section Headings --- */
h2 { font-size: 1.8rem; color: var(--techslate); margin-bottom: 25px; position: relative; padding-bottom: 10px; font-weight: 800; }
h2::after { content: ''; position: absolute; left: 0; bottom: 0; width: 50px; height: 4px; background-color: var(--linkblue); border-radius: 2px; }
h3 { font-size: 1.2rem; color: var(--techslate); font-weight: 700; margin-bottom: 8px; }

/* --- Research Vision & Impact --- */
.vision-text { font-size: 1.1rem; color: var(--textgray); line-height: 1.7; margin-bottom: 20px; max-width: 900px; }
.focus-block { background-color: #EBF5FB; border-left: 4px solid var(--linkblue); padding: 18px 20px; border-radius: 0 8px 8px 0; margin-bottom: 25px; font-size: 1.05rem; color: var(--techslate); line-height: 1.6; }
.focus-block strong { color: var(--linkblue); font-weight: 800; display: block; margin-bottom: 6px; text-transform: uppercase; font-size: 0.85rem; letter-spacing: 0.5px; }

.news-ticker { background-color: var(--lightbg); border: 1px solid var(--bordergray); padding: 15px 20px; border-radius: 8px; margin-bottom: 25px; }
.news-ticker h3 { font-size: 1.05rem; margin-bottom: 10px; color: var(--techslate); }
.news-ticker ul { list-style: none; font-size: 0.95rem; color: var(--textgray); }
.news-ticker li { margin-bottom: 6px; display: flex; gap: 8px; }
.news-ticker li strong { color: var(--techslate); min-width: 80px; flex-shrink: 0; }

/* --- Impact Grid --- */
.contrib-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 20px; margin-top: 15px; }
.contrib-card { background: #FFFFFF; border: 1px solid var(--bordergray); border-radius: 8px; padding: 20px; box-shadow: 0 2px 4px rgba(0,0,0,0.02); display: flex; flex-direction: column; border-top: 4px solid var(--linkblue); transition: transform 0.2s, box-shadow 0.2s; }
.contrib-card:hover { transform: translateY(-4px); box-shadow: 0 8px 16px rgba(0,0,0,0.06); }
.contrib-card h3 { font-size: 1.15rem; color: var(--techslate); font-weight: 700; margin-bottom: 10px; }
.contrib-card p { font-size: 0.95rem; color: #4A5568; line-height: 1.5; }

/* --- Publications --- */
.pub-list { list-style: none; margin-bottom: 20px; }
.pub-item { margin-bottom: 25px; padding-left: 18px; border-left: 3px solid var(--bordergray); transition: border-color 0.2s; }
.pub-item:hover { border-left-color: var(--linkblue); }
.pub-year { font-size: 0.85rem; color: var(--linkblue); font-weight: 700; margin-bottom: 2px; }
.pub-title { font-weight: 700; font-size: 1.1rem; color: var(--techslate); margin-bottom: 4px; line-height: 1.3; }
.pub-venue { font-size: 0.95rem; color: #4A5568; font-weight: 600; margin-bottom: 4px; }
.pub-summary { font-size: 0.95rem; color: #4A5568; font-style: italic; margin-bottom: 12px; line-height: 1.5; max-width: 850px; }
.pub-actions { display: flex; gap: 8px; flex-wrap: wrap; }
@keyframes fadeInDown { from { opacity: 0; transform: translateY(-10px); } to { opacity: 1; transform: translateY(0); } }
.drawer-anim { animation: fadeInDown 0.4s ease-out forwards; }

/* --- Hardware Projects --- */
.project-block { display: flex; flex-wrap: wrap; gap: 40px; margin-bottom: 35px; }
.project-info { flex: 1 1 400px; }
.project-media { flex: 1 1 500px; }
.project-objective { font-size: 1.05rem; margin-bottom: 15px; color: var(--textgray); line-height: 1.7; }
.project-role { font-size: 0.95rem; background-color: #F0F4F8; padding: 12px 15px; border-left: 3px solid var(--techslate); border-radius: 4px; margin-bottom: 15px; color: var(--textgray); }
.project-outcome { font-size: 0.95rem; font-weight: 500; color: var(--linkblue); background-color: var(--lightbg); padding: 12px 15px; border-left: 3px solid var(--linkblue); border-radius: 4px; margin-bottom: 20px; }

.spec-list { list-style: none; margin-bottom: 20px; }
.spec-list li { font-size: 0.95rem; margin-bottom: 10px; display: flex; align-items: baseline; gap: 10px; }
.spec-list li i { color: var(--linkblue); font-size: 0.85rem; padding-top: 4px; }
.tech-tags { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 25px; }
.tech-tags span { background: var(--lightbg); color: var(--linkblue); font-size: 0.8rem; font-weight: 700; padding: 6px 14px; border-radius: 20px; border: 1px solid var(--bordergray); }

.video-container { position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; background: #000; cursor: pointer; border-radius: 10px; box-shadow: 0 4px 12px rgba(0,0,0,0.1); border: 1px solid var(--bordergray); margin-bottom: 20px; transition: transform 0.2s, box-shadow 0.2s; }
.video-container:hover { transform: translateY(-4px); box-shadow: 0 8px 24px rgba(0,0,0,0.15); }
.video-container iframe, .video-container img { position: absolute; top: 0; left: 0; width: 100%; height: 100%; border: 0; object-fit: cover; }
.play-overlay-btn { position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); font-size: 4rem; color: rgba(255, 255, 255, 0.9); z-index: 2; pointer-events: none; text-shadow: 0 4px 12px rgba(0,0,0,0.4); transition: transform 0.2s, color 0.2s; }
.video-container:hover .play-overlay-btn { color: var(--ytred); transform: translate(-50%, -50%) scale(1.1); }

/* --- Sim Grid --- */
.sim-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 25px; margin-top: 20px; }
.sim-card { background: #FFFFFF; border: 1px solid var(--bordergray); border-radius: 10px; overflow: hidden; box-shadow: 0 2px 4px rgba(0,0,0,0.02); display: flex; flex-direction: column; transition: transform 0.2s, box-shadow 0.2s; }
.sim-card:hover { transform: translateY(-4px); box-shadow: 0 8px 16px rgba(0,0,0,0.06); }
.sim-card .video-container { margin-bottom: 0; border-radius: 10px 10px 0 0; border: none; border-bottom: 1px solid var(--bordergray); box-shadow: none; }
.sim-card .video-container iframe { border-radius: 10px 10px 0 0; }
.sim-content { padding: 20px; flex-grow: 1; display: flex; flex-direction: column; }
.sim-content h3 { font-size: 1.1rem; color: var(--techslate); margin-bottom: 8px; line-height: 1.3; font-weight: 700; }
.sim-content p { font-size: 0.95rem; color: #4A5568; line-height: 1.5; margin-bottom: 15px; flex-grow: 1; }
.sim-tags { display: flex; flex-wrap: wrap; gap: 6px; list-style: none; margin-top: auto; }
.sim-tags li { background: var(--lightbg); color: var(--linkblue); font-size: 0.75rem; font-weight: 700; padding: 4px 10px; border-radius: 20px; border: 1px solid var(--bordergray); }

/* --- Research Themes Grid --- */
.repo-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 20px; margin-top: 20px; }
.repo-card { background: #FFFFFF; border: 1px solid var(--bordergray); border-radius: 8px; padding: 20px; box-shadow: 0 2px 4px rgba(0,0,0,0.02); display: flex; flex-direction: column; justify-content: space-between; border-top: 4px solid var(--linkblue); transition: transform 0.2s, box-shadow 0.2s; }
.repo-card:hover { transform: translateY(-4px); box-shadow: 0 8px 16px rgba(0,0,0,0.06); }
.repo-header { display: flex; align-items: center; gap: 12px; margin-bottom: 10px; }
.repo-header i { font-size: 1.2rem; color: var(--techslate); }
.repo-description { font-size: 0.95rem; color: #4A5568; line-height: 1.5; }

/* --- Education & Appointments Timeline --- */
.timeline-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 15px; margin-top: 20px; }
.timeline-card { background: #FFFFFF; border: 1px solid var(--bordergray); border-left: 4px solid var(--techslate); padding: 16px; border-radius: 0 8px 8px 0; box-shadow: 0 2px 4px rgba(0,0,0,0.02); transition: border-color 0.2s; }
.timeline-card:hover { border-left-color: var(--linkblue); }
.timeline-year { font-size: 1.2rem; font-weight: 800; color: var(--linkblue); margin-bottom: 4px; }
.timeline-title { font-size: 0.95rem; font-weight: 600; color: var(--techslate); line-height: 1.4; }

/* --- Technical Skills Matrix --- */
.skills-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 20px; margin-top: 20px; }
.skills-category { background: var(--lightbg); padding: 20px; border-radius: 8px; border: 1px solid var(--bordergray); }
.skills-category h3 { font-size: 1.05rem; color: var(--techslate); margin-bottom: 12px; border-bottom: 2px solid var(--bordergray); padding-bottom: 6px; }
.skills-category ul { list-style: none; font-size: 0.95rem; color: #4A5568; line-height: 1.7; }
.skills-category ul li::before { content: '▹'; color: var(--linkblue); margin-right: 6px; font-weight: bold; }

/* --- Academic Block Elements (Funding/Awards) --- */
.academic-block { margin-bottom: 25px; padding-left: 15px; border-left: 3px solid var(--bordergray); }
.academic-block-title { font-weight: 700; color: var(--techslate); font-size: 1.05rem; }
.academic-block-meta { font-size: 0.85rem; color: var(--linkblue); font-weight: 700; margin-bottom: 4px; text-transform: uppercase; }
.academic-block-desc { font-size: 0.9rem; color: #4A5568; margin-top: 4px; }

/* --- Buttons --- */
.btn-small { font-size: 0.85rem; padding: 6px 14px; background: var(--lightbg); color: var(--techslate); border: 1px solid var(--bordergray); border-radius: 6px; font-weight: 600; cursor: pointer; transition: all 0.2s; display: inline-flex; align-items: center; gap: 6px; }
.btn-small:hover { background: var(--bordergray); transform: translateY(-2px); box-shadow: 0 2px 4px rgba(0,0,0,0.05); }

.btn { display: inline-flex; align-items: center; gap: 8px; padding: 12px 24px; background-color: var(--techslate); color: #FFFFFF; font-weight: 600; border-radius: 8px; font-size: 0.95rem; border: none; cursor: pointer; transition: all 0.2s; box-shadow: 0 4px 6px rgba(0,0,0,0.1); }
.btn:hover { background-color: var(--linkblue); color: #FFFFFF; transform: translateY(-2px); box-shadow: 0 6px 12px rgba(0,0,0,0.15); }
.btn-secondary { background-color: #718096; }

/* --- Call to Action & Footer --- */
#opportunities { background-color: var(--linkblue); color: #FFFFFF; text-align: center; padding: 60px 20px; }
#opportunities h2 { color: #FFFFFF; font-weight: 800; }
#opportunities h2::after { display: none; }

footer { background: var(--techslate); padding: 50px 0; color: #FFFFFF; border-top: 1px solid var(--bordergray); }
.contact-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 40px; text-align: left; }
.footer-text { font-size: 0.95rem; color: #CBD5E0; line-height: 1.7; }
.footer-links a { color: #3498DB; display: block; margin-bottom: 10px; font-weight: 600; font-size: 0.95rem; transition: color 0.2s; }
.footer-links a:hover { color: #FFFFFF; }
.availability-list { list-style: none; margin-top: 10px; font-size: 0.9rem; color: #A0AEC0; }
.availability-list li { margin-bottom: 4px; }
.availability-list li::before { content: '•'; color: var(--linkblue); margin-right: 6px; }

/* --- Responsive Viewport Logic --- */
@media (max-width: 768px) {
    .hero-layout { flex-direction: column; text-align: center; gap: 25px; }
    .hero-photo-container { order: -1; } 
    .social-links, .btn-group { justify-content: center; }
    body { padding-top: 60px; }
    .menu-toggle { display: block; }
    
    /* Mobile adjustment for language switcher */
    .lang-switch { margin-left: auto; margin-right: 20px; }
    
    .nav-links { display: none; flex-direction: column; position: absolute; top: 60px; left: 0; width: 100%; background-color: rgba(33, 47, 61, 0.98); padding: 15px 20px; gap: 15px; border-bottom: 1px solid rgba(255,255,255,0.1); box-shadow: 0 4px 12px rgba(0,0,0,0.1); }
    .nav-links.active { display: flex; margin-left: 0; margin-right: 0; }
    .pub-actions { justify-content: flex-start; }
}