:root {
    /* Dark Theme (Default) */
    --bg-color: #0f172a;
    --surface-color: #1e293b;
    --surface-hover: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #3b82f6;
    --accent-glow: rgba(59, 130, 246, 0.4);
    --border-color: rgba(255, 255, 255, 0.08);
    --nav-bg: rgba(15, 23, 42, 0.85);
    --font-main: 'Inter', sans-serif;
    --transition-speed: 0.3s;
    --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.5), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
    --hover-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.5), 0 10px 10px -5px rgba(0, 0, 0, 0.3);
}

:root[data-theme="light"] {
    --bg-color: #f8fafc;
    --surface-color: #ffffff;
    --surface-hover: #f1f5f9;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --accent-color: #2563eb;
    --accent-glow: rgba(37, 99, 235, 0.25);
    --border-color: rgba(0, 0, 0, 0.08);
    --nav-bg: rgba(248, 250, 252, 0.85);
    --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03);
    --hover-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    transition: background-color var(--transition-speed), border-color var(--transition-speed);
}

html { scroll-behavior: smooth; }

body {
    font-family: var(--font-main);
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

h1, h2, h3, h4, h5, h6 { font-weight: 700; line-height: 1.2; margin-bottom: 1rem; color: var(--text-primary); }

h1 {
    font-size: 4rem;
    background: linear-gradient(135deg, var(--text-primary), var(--text-secondary));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.02em;
}

h2 { font-size: 2.75rem; margin-bottom: 2.5rem; position: relative; display: inline-block; }
h2::after { content: ''; position: absolute; bottom: -10px; left: 0; width: 60px; height: 4px; background: var(--accent-color); border-radius: 4px; box-shadow: 0 0 10px var(--accent-glow); }
p { color: var(--text-secondary); margin-bottom: 1.5rem; font-size: 1.1rem; }
a { text-decoration: none; color: inherit; transition: color var(--transition-speed); }
ul { list-style: none; }

.container { max-width: 1200px; margin: 0 auto; padding: 0 2rem; }
.section { padding: 7rem 0; }

.btn {
    display: inline-flex; align-items: center; justify-content: center;
    padding: 0.9rem 2.2rem; background: var(--accent-color); color: white !important;
    border-radius: 50px; font-weight: 600; font-size: 1rem; border: 2px solid var(--accent-color);
    transition: all var(--transition-speed); cursor: pointer;
    box-shadow: 0 4px 15px var(--accent-glow); text-transform: uppercase; letter-spacing: 1px;
}
.btn:hover { background: transparent; color: var(--accent-color) !important; box-shadow: 0 0 25px var(--accent-glow); transform: translateY(-2px); }

.btn-outline { background: transparent; border: 2px solid var(--text-secondary); color: var(--text-primary) !important; box-shadow: none; }
.btn-outline:hover { border-color: var(--accent-color); color: var(--accent-color) !important; box-shadow: 0 0 20px var(--accent-glow); }

/* Navigation */
.navbar {
    position: fixed; top: 0; width: 100%; padding: 1.5rem 0;
    background: var(--nav-bg); backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
    z-index: 1000; transition: all var(--transition-speed); border-bottom: 1px solid transparent;
}
.navbar.scrolled { padding: 1rem 0; border-bottom: 1px solid var(--border-color); box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1); }

.nav-content { display: flex; justify-content: space-between; align-items: center; }
.nav-right { display: flex; align-items: center; gap: 2.5rem; }

.logo { font-size: 1.6rem; font-weight: 800; letter-spacing: -1px; background: linear-gradient(135deg, var(--accent-color), #8b5cf6); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }

.nav-links { display: flex; gap: 2rem; align-items: center; }
.nav-link { font-size: 0.95rem; font-weight: 500; color: var(--text-secondary); position: relative; padding-bottom: 0.25rem; }
.nav-link:hover, .nav-link.active { color: var(--text-primary); }
.nav-link::after { content: ''; position: absolute; bottom: -2px; left: 0; width: 0; height: 2px; background: var(--accent-color); transition: width var(--transition-speed); border-radius: 2px; }
.nav-link:hover::after, .nav-link.active::after { width: 100%; }

.nav-controls { display: flex; align-items: center; gap: 1.5rem; }
#theme-toggle, #hamburger { background: none; border: none; color: var(--text-primary); font-size: 1.2rem; cursor: pointer; transition: color var(--transition-speed), transform 0.2s; display: flex; align-items: center; justify-content: center; }
#theme-toggle:hover { color: var(--accent-color); transform: scale(1.1); }
#hamburger { display: none; }

/* Hero Section */
.hero { min-height: 100vh; display: flex; align-items: center; position: relative; overflow: hidden; padding-top: 80px; }
.hero::before { content: ''; position: absolute; top: -20%; right: -10%; width: 70vw; height: 70vw; background: radial-gradient(circle, var(--accent-glow) 0%, transparent 60%); opacity: 0.8; z-index: -1; border-radius: 50%; filter: blur(80px); }
.hero-content { max-width: 850px; position: relative; z-index: 10; }
.hero-subtitle { color: var(--accent-color); font-weight: 700; letter-spacing: 3px; margin-bottom: 1.5rem; display: block; text-transform: uppercase; font-size: 1rem; }
.hero p { font-size: 1.25rem; max-width: 600px; color: var(--text-secondary); margin-bottom: 2.5rem; }
.hero-buttons { display: flex; gap: 1.25rem; }

/* About Section */
.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 5rem; align-items: center; }
.about-img-wrapper { position: relative; border-radius: 24px; overflow: hidden; box-shadow: var(--hover-shadow); }
.about-img-wrapper::before { content: ''; position: absolute; inset: 0; background: linear-gradient(to top, rgba(15, 23, 42, 0.4), transparent); z-index: 1; }
.about-img { width: 100%; display: block; border-radius: 24px; filter: grayscale(80%) contrast(1.1); transition: filter 0.5s ease, transform 0.5s ease; }
.about-img-wrapper:hover .about-img { filter: grayscale(0%) contrast(1); transform: scale(1.05); }
.about-stats { display: grid; grid-template-columns: repeat(2, 1fr); gap: 2.5rem; margin-top: 3rem; padding-top: 2rem; border-top: 1px solid var(--border-color); }
.stat-item h3 { font-size: 2.5rem; color: var(--accent-color); margin-bottom: 0.25rem; font-weight: 800; }
.stat-item p { font-size: 1rem; margin: 0; text-transform: uppercase; letter-spacing: 1px; font-weight: 600; color: var(--text-primary); }

/* Experience Section */
.timeline { position: relative; max-width: 850px; margin: 0 auto; }
.timeline::before { content: ''; position: absolute; left: 19.5px; top: 10px; height: calc(100% - 10px); width: 3px; background: linear-gradient(to bottom, var(--accent-color), transparent); opacity: 0.5; }
.timeline-item { padding-left: 4.5rem; position: relative; margin-bottom: 4.5rem; }
.timeline-item:last-child { margin-bottom: 0; }
.timeline-dot { position: absolute; left: 11px; top: 6px; width: 20px; height: 20px; background: var(--surface-color); border: 4px solid var(--accent-color); border-radius: 50%; box-shadow: 0 0 15px var(--accent-glow); z-index: 2; }
.timeline-date { display: inline-block; padding: 0.4rem 1.2rem; background: var(--accent-glow); color: var(--accent-color); border-radius: 50px; font-size: 0.9rem; font-weight: 700; margin-bottom: 1rem; border: 1px solid rgba(59, 130, 246, 0.2); }
.timeline-content { background: var(--surface-color); padding: 2.5rem; border-radius: 16px; border: 1px solid var(--border-color); transition: all var(--transition-speed); box-shadow: var(--card-shadow); position: relative; overflow: hidden; }
.timeline-content::before { content: ''; position: absolute; top: 0; left: 0; width: 4px; height: 100%; background: var(--accent-color); transform: scaleY(0); transition: transform var(--transition-speed); transform-origin: top; }
.timeline-content:hover { transform: translateY(-8px); border-color: rgba(59, 130, 246, 0.4); box-shadow: var(--hover-shadow); }
.timeline-content:hover::before { transform: scaleY(1); }
.timeline-content h3 { font-size: 1.4rem; margin-bottom: 0.5rem; }
.timeline-content h4 { font-size: 1.1rem; color: var(--accent-color); font-weight: 600; margin-bottom: 1.5rem; }
.timeline-content ul { list-style: none; padding-left: 0; color: var(--text-secondary); }
.timeline-content ul li { position: relative; padding-left: 1.5rem; margin-bottom: 0.75rem; }
.timeline-content ul li::before { content: "▹"; position: absolute; left: 0; color: var(--accent-color); font-weight: bold; }

/* Skills Section */
.skills-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(160px, 1fr)); gap: 2rem; }
.skill-card { background: var(--surface-color); padding: 2.5rem 1.5rem; border-radius: 16px; text-align: center; border: 1px solid var(--border-color); transition: all var(--transition-speed); box-shadow: var(--card-shadow); display: flex; flex-direction: column; align-items: center; justify-content: center; }
.skill-card:hover { background: var(--surface-hover); border-color: var(--accent-color); transform: translateY(-10px); box-shadow: 0 15px 30px var(--accent-glow); }
.skill-icon { font-size: 3rem; margin-bottom: 1.25rem; color: var(--text-primary); transition: color var(--transition-speed); }
.skill-card:hover .skill-icon { color: var(--accent-color); }
.skill-name { font-weight: 600; font-size: 1rem; color: var(--text-primary); }

/* Projects Section */
.projects-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(340px, 1fr)); gap: 2.5rem; }
.project-card { background: var(--surface-color); border-radius: 20px; overflow: hidden; border: 1px solid var(--border-color); transition: all var(--transition-speed); display: flex; flex-direction: column; box-shadow: var(--card-shadow); }
.project-card:hover { transform: translateY(-10px); border-color: rgba(59, 130, 246, 0.4); box-shadow: var(--hover-shadow); }
.project-img-wrapper { height: 240px; overflow: hidden; position: relative; border-bottom: 1px solid var(--border-color); }
.project-img-wrapper::after { content: ''; position: absolute; inset: 0; background: linear-gradient(to top, rgba(15, 23, 42, 0.8), transparent); opacity: 0; transition: opacity var(--transition-speed); }
.project-card:hover .project-img-wrapper::after { opacity: 1; }
.project-img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.6s cubic-bezier(0.16, 1, 0.3, 1); }
.project-card:hover .project-img { transform: scale(1.1); }
.project-content { padding: 2.5rem; flex: 1; display: flex; flex-direction: column; }
.project-content h3 { margin-bottom: 1rem; font-size: 1.5rem; }
.project-content p { color: var(--text-secondary); font-size: 1.05rem; line-height: 1.7; margin-bottom: 2rem; flex: 1; }
.project-link { display: inline-flex; align-items: center; gap: 0.75rem; color: var(--text-primary); font-weight: 600; font-size: 1rem; transition: all var(--transition-speed); align-self: flex-start; }
.project-link i { color: var(--accent-color); transition: transform var(--transition-speed); }
.project-link:hover { color: var(--accent-color); }
.project-link:hover i { transform: translateX(5px); }

/* Contact Section */
.contact-content { text-align: center; width: calc(100% - 2rem); max-width: 650px; margin: 0 auto; background: var(--surface-color); padding: 4rem 2rem; border-radius: 24px; border: 1px solid var(--border-color); box-shadow: var(--card-shadow); }
.social-links { display: flex; justify-content: center; gap: 1.5rem; margin-top: 3.5rem; flex-wrap: wrap; }
.social-link { width: 56px; height: 56px; display: flex; align-items: center; justify-content: center; background: var(--bg-color); border: 1px solid var(--border-color); border-radius: 50%; font-size: 1.4rem; color: var(--text-primary); transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275); }
.social-link:hover { background: var(--accent-color); color: white; transform: translateY(-8px) scale(1.1); box-shadow: 0 10px 20px var(--accent-glow); border-color: var(--accent-color); }

/* Footer */
footer { padding: 2.5rem 0; text-align: center; color: var(--text-secondary); font-size: 1rem; border-top: 1px solid var(--border-color); background: var(--surface-color); margin-top: auto; }

/* Animations */
.fade-in { opacity: 0; transform: translateY(30px); transition: opacity 0.8s ease-out, transform 0.8s ease-out; }
.fade-in.visible { opacity: 1; transform: translateY(0); }

/* Responsive Variables */
@media (max-width: 992px) {
    h1 { font-size: 3rem; }
    h2 { font-size: 2.25rem; }
    .about-grid { gap: 3rem; }
    .hero::before { width: 100vw; height: 100vw; right: -20%; top: -10%; }
}

@media (max-width: 768px) {
    .section { padding: 5rem 0; }
    h1 { font-size: 2.5rem; }
    
    #hamburger { display: flex; z-index: 1001; }
    
    .nav-links {
        position: absolute; top: 100%; left: 0; width: 100%;
        background: var(--nav-bg); backdrop-filter: blur(16px); -webkit-backdrop-filter: blur(16px);
        flex-direction: column; align-items: center; padding: 2rem 0; gap: 1.5rem;
        border-bottom: 1px solid var(--border-color); box-shadow: 0 10px 30px rgba(0,0,0,0.2);
        opacity: 0; visibility: hidden; transform: translateY(-20px); transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    }
    
    .nav-links.active { opacity: 1; visibility: visible; transform: translateY(0); }
    
    .nav-link { font-size: 1.1rem; }
    .about-grid { grid-template-columns: 1fr; }
    .about-img-wrapper { max-width: 400px; margin: 0 auto; }
    
    .timeline::before { left: 9.5px; }
    .timeline-dot { left: 2px; width: 18px; height: 18px; }
    .timeline-item { padding-left: 3rem; }
    .timeline-content { padding: 1.5rem; }

    .hero { text-align: center; }
    .hero-content { margin: 0 auto; }
    .hero-subtitle { margin-bottom: 1rem; }
    .hero p { margin: 0 auto 2rem; }
    .hero-buttons { justify-content: center; }
}

@media (max-width: 480px) {
    .container { padding: 0 1.5rem; }
    h1 { font-size: 2.2rem; }
    .btn { padding: 0.8rem 1.8rem; width: 100%; margin-bottom: 1rem; }
    .hero-buttons { flex-direction: column; }
    .contact-content { padding: 2rem 1rem; width: calc(100% - 2rem); margin: 0 auto; }
    .social-links { gap: 1rem; }
    .social-link { width: 48px; height: 48px; font-size: 1.2rem; }
    .projects-grid { grid-template-columns: 1fr; }
}