:root {
    --primary-blue: #3B82F6;
    --secondary-gray: #6B7280;
    --accent-teal: #14B8A6;
    --dark-bg: #1F2937;
    --light-bg: #F3F4F6;
    --white: #FFFFFF;
    --success: #10B981;
    --warning: #F59E0B;
    --error: #EF4444;
    --transition: all 0.3s ease;
}

/* RESET & BASE */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: #374151;
    background-color: var(--white);
}
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* TYPOGRAPHY */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    color: var(--dark-bg);
    margin-bottom: 10px;
}
h1 { font-size: 3rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
p { margin-bottom: 10px; }
a {
    color: var(--primary-blue);
    text-decoration: none;
    transition: var(--transition);
}
a:hover { color: var(--accent-teal); text-decoration: underline; }

/* BUTTONS */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
}
.btn--primary {
    background: linear-gradient(135deg, var(--primary-blue), #1E40AF);
    color: var(--white);
}
.btn--primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(59, 130, 246, 0.3);
}
.btn--secondary {
    background: var(--light-bg);
    color: var(--primary-blue);
    border: 1px solid var(--primary-blue);
}
.btn--secondary:hover {
    background: var(--primary-blue);
    color: var(--white);
}

/* BADGES */
.badge {
    display: inline-block;
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 12px;
    font-weight: 600;
    margin: 5px 5px 5px 0;
}
.badge--primary {
    background: linear-gradient(135deg, var(--primary-blue), #1E40AF);
    color: var(--white);
}
.badge--success {
    background: linear-gradient(135deg, #10B981, #059669);
    color: var(--white);
}
.badge--info {
    background: linear-gradient(135deg, var(--accent-teal), #0D9488);
    color: var(--white);
}
.badge--current {
    background: #FEE2E2;
    color: var(--error);
}
.badge--achievement {
    background: linear-gradient(135deg, #F59E0B, #D97706);
    color: var(--white);
    font-size: 13px;
}
.badge--impact {
    background: linear-gradient(135deg, #8B5CF6, #7C3AED);
    color: var(--white);
    font-size: 13px;
}
.badge--forensics {
    background: linear-gradient(135deg, #EF4444, #DC2626);
    color: var(--white);
    font-size: 13px;
}
.badge--ml {
    background: linear-gradient(135deg, #06B6D4, #0891B2);
    color: var(--white);
    font-size: 13px;
}
.badge--publication {
    background: linear-gradient(135deg, #14B8A6, #0D9488);
    color: var(--white);
    font-size: 13px;
}
.badges-group {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin: 15px 0;
}

/* HEADER & NAV */
.header {
    background: var(--white);
    border-bottom: 1px solid #E5E7EB;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}
.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 0;
}
.nav-brand h2 { color: var(--primary-blue); margin: 0; }
.nav-links {
    display: flex;
    align-items: center;
    gap: 20px;
}
.nav-link {
    font-size: 14px;
    font-weight: 500;
    color: var(--secondary-gray);
    transition: var(--transition);
}
.nav-link:hover { color: var(--primary-blue); }

/* HERO */
.hero {
    background: linear-gradient(135deg, #F3F4F6 0%, #E5E7EB 100%);
    padding: 60px 0;
}
.hero-content { text-align: center; }
.hero-title {
    font-size: 3.5rem;
    margin-bottom: 10px;
    background: linear-gradient(135deg, var(--primary-blue), var(--accent-teal));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.hero-subtitle {
    font-size: 1.5rem;
    color: var(--secondary-gray);
    margin-bottom: 20px;
}
.hero-meta {
    margin: 20px 0;
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
}
.hero-meta p { font-size: 14px; margin: 0; }
.hero-summary {
    max-width: 700px;
    margin: 20px auto;
    font-size: 16px;
    color: var(--secondary-gray);
}

/* SECTIONS */
.section { padding: 60px 0; border-bottom: 1px solid #E5E7EB; }
.section-title { text-align: center; margin-bottom: 40px; font-size: 2.5rem; }
.section--skills { background: var(--light-bg); }
.section--experience { background: var(--white); }
.section--projects { background: var(--light-bg); }
.section--real-world { background: var(--white); }
.section--publications { background: var(--light-bg); }
.section--contact { background: var(--dark-bg); color: var(--white); }
.section--contact .section-title { color: var(--white); }

/* SKILLS */
.skills-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 30px; }
.skills-column h3 { margin-bottom: 15px; color: var(--primary-blue); }
.skills-list { display: flex; flex-wrap: wrap; gap: 10px; }
.skill-tag {
    display: inline-block; padding: 8px 15px; background: var(--white);
    border: 1px solid #D1D5DB; border-radius: 20px; font-size: 13px; transition: var(--transition);
}
.skill-tag:hover { background: var(--primary-blue); color: var(--white); border-color: var(--primary-blue); }

/* EXPERIENCE */
.experience-list { display: grid; gap: 25px; }
.experience-card {
    background: var(--white); padding: 25px; border-radius: 8px;
    border-left: 4px solid var(--primary-blue); transition: var(--transition);
}
.experience-card:hover { box-shadow: 0 10px 30px rgba(0,0,0,0.1); }
.experience-header { margin-bottom: 15px; }
.experience-title { margin-bottom: 5px; font-size: 1.3rem; }
.experience-company { font-weight: 600; color: var(--primary-blue); margin: 5px 0; }
.experience-period { color: var(--secondary-gray); font-size: 14px; }
.experience-content h4 { margin-top: 15px; margin-bottom: 10px; }
.experience-content ul { margin-left: 20px; margin-bottom: 15px; }
.experience-content li { margin-bottom: 8px; color: #4B5563; }
.tech-stack { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 15px; }
.tech-tag {
    display: inline-block; padding: 5px 12px; background: #E0E7FF;
    color: #3B82F6; border-radius: 15px; font-size: 12px; font-weight: 500;
}

/* PROJECTS */
.projects-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 25px; }
.project-card {
    background: var(--white); padding: 25px; border-radius: 8px; border-top: 3px solid var(--primary-blue);
    transition: var(--transition);
}
.project-card:hover { transform: translateY(-5px); box-shadow: 0 15px 40px rgba(59, 130, 246, 0.15); }
.project-title { font-size: 1.2rem; margin-bottom: 8px; }
.project-company { font-size: 13px; color: var(--primary-blue); font-weight: 600; margin-bottom: 10px; }
.project-description { color: var(--secondary-gray); margin-bottom: 15px; }

/* REAL-WORLD PROJECTS */
.real-world-projects { display: grid; gap: 30px; }
.real-world-card {
    background: var(--white); padding: 30px; border-radius: 10px; border-left: 5px solid #8B5CF6;
    position: relative;
}
.real-world-card.featured { border-left-color: #EF4444;
    background: linear-gradient(135deg, #FEF2F2 0%, var(--white) 100%);
    box-shadow: 0 10px 30px rgba(239, 68, 68, 0.15); }
.featured-badge {
    position: absolute; top: 15px; right: 15px; background: #EF4444; color: var(--white);
    padding: 6px 12px; border-radius: 20px; font-size: 12px; font-weight: 600;
}
.project-subtitle { font-size: 14px; color: var(--secondary-gray); margin-bottom: 15px; font-style: italic; }
.project-links { display: flex; gap: 10px; margin-top: 20px; flex-wrap: wrap; }

/* PUBLICATIONS */
.publications-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 25px; }
.publication-card {
    background: var(--white); padding: 25px; border-radius: 8px; border: 1px solid #E5E7EB; transition: var(--transition);
}
.publication-card:hover { box-shadow: 0 10px 30px rgba(0,0,0,0.1); border-color: var(--primary-blue); }
.publication-title { font-size: 1.2rem; margin-bottom: 8px; }
.publication-date { font-size: 12px; color: var(--secondary-gray); margin-bottom: 10px; }
.publication-description { color: var(--secondary-gray); margin-bottom: 15px; }

/* EDUCATION */
.education-card {
    background: var(--white); padding: 25px; border-radius: 8px; border-left: 4px solid var(--accent-teal);
    max-width: 600px; margin: 0 auto;
}
.education-school { font-weight: 600; color: var(--primary-blue); margin: 10px 0; }
.education-detail { color: var(--secondary-gray); margin: 8px 0; }
.education-period { font-size: 14px; color: var(--secondary-gray); }

/* QUICK LINKS */
.quick-links-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 20px; }
.quick-link-card {
    display: flex; flex-direction: column; align-items: center; text-align: center;
    padding: 25px; background: var(--white); border-radius: 10px;
    transition: var(--transition); border: 2px solid transparent;
}
.quick-link-card:hover {
    transform: translateY(-5px); border-color: var(--primary-blue);
    box-shadow: 0 10px 25px rgba(59, 130, 246, 0.15);
}
.quick-link-card i { font-size: 2rem; color: var(--primary-blue); margin-bottom: 15px; }
.quick-link-card h3 { font-size: 1.1rem; margin-bottom: 8px; }
.quick-link-card p { font-size: 13px; color: var(--secondary-gray); }

/* CONTACT */
.contact-wrapper { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; max-width: 1000px; margin: 0 auto; }
.contact-info p { margin-bottom: 12px; font-size: 15px; }
.contact-info a { color: var(--accent-teal); }
.contact-info a:hover { color: var(--white); text-decoration: underline; }
.availability { margin-top: 30px; padding-top: 30px; border-top: 1px solid rgba(255,255,255,0.2); }
.availability h3 { color: var(--white); margin-bottom: 15px; }

/* CONTACT FORM */
.form-group { margin-bottom: 20px; }
.form-group label {
    display: block; margin-bottom: 8px; font-weight: 600; color: var(--white);
}
.form-group input,
.form-group textarea,
.form-group select {
    width: 100%; padding: 12px; border: 1px solid rgba(255,255,255,0.2); border-radius: 6px;
    background: rgba(255,255,255,0.1); color: var(--white); font-family: inherit; font-size: 14px;
    transition: var(--transition);
}
.form-group input::placeholder, .form-group textarea::placeholder { color: rgba(255,255,255,0.6); }
.form-group input:focus, .form-group textarea:focus, .form-group select:focus {
    outline: none; background: rgba(255,255,255,0.15); border-color: var(--accent-teal);
}
.form-group select { cursor: pointer; }
.form-group select option { background: var(--dark-bg); color: var(--white); }
.contact-form button { width: 100%; }

/* FOOTER */
.footer {
    background: #111827;
    color: #D1D5DB;
    padding: 30px 0;
    text-align: center;
}
.footer p { font-size: 14px; }

/* RESPONSIVE DESIGN */
@media (max-width: 768px) {
    .hero-title { font-size: 2.2rem; }
    .hero-meta { flex-direction: column; gap: 10px; }
    .nav-links { display: none; }
    .section { padding: 40px 0; }
    .section-title { font-size: 1.8rem; margin-bottom: 30px; }
    .skills-grid { grid-template-columns: 1fr; }
    .projects-grid { grid-template-columns: 1fr; }
    .publications-grid { grid-template-columns: 1fr; }
    .contact-wrapper { grid-template-columns: 1fr; gap: 30px; }
    .quick-links-grid { grid-template-columns: repeat(2, 1fr); }
    h1 { font-size: 2rem; }
    h2 { font-size: 1.5rem; }
    h3 { font-size: 1.2rem; }
}
@media (max-width: 480px) {
    .container { padding: 0 15px; }
    .hero-title { font-size: 1.8rem; }
    .hero-subtitle { font-size: 1.1rem; }
    .nav-brand h2 { font-size: 1.2rem; }
    .section-title { font-size: 1.5rem; }
    .badges-group { justify-content: center; }
    .quick-links-grid { grid-template-columns: 1fr; }
    .btn { width: 100%; justify-content: center; }
    .project-links { flex-direction: column; }
    .project-links .btn { width: 100%; }
}