:root {
    --color-primary: #2563EB;
    --color-primary-dark: #1D4ED8;
    --color-primary-light: #3B82F6;
    --color-primary-bg: #EFF6FF;
    --color-text: #1F2937;
    --color-text-secondary: #6B7280;
    --color-text-light: #9CA3AF;
    --color-bg: #FFFFFF;
    --color-bg-alt: #F9FAFB;
    --color-border: #E5E7EB;
    --color-card-shadow: rgba(0, 0, 0, 0.06);
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --max-width: 1100px;
    --nav-height: 64px;
    --radius: 10px;
    --radius-sm: 6px;
    --transition: 0.2s ease;
}
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: var(--nav-height); }
body { font-family: var(--font-family); color: var(--color-text); background: var(--color-bg); line-height: 1.7; -webkit-font-smoothing: antialiased; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }
img { max-width: 100%; display: block; }
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 24px; }
.section { padding: 80px 0; }
.section-alt { background: var(--color-bg-alt); }
.section-title { font-size: 1.75rem; font-weight: 700; margin-bottom: 12px; color: var(--color-text); position: relative; display: inline-block; }
.section-title::after { content: ''; display: block; width: 40px; height: 3px; background: var(--color-primary); border-radius: 2px; margin-top: 8px; }
.section-subtitle { color: var(--color-text-secondary); font-size: 1rem; margin-bottom: 40px; }
.nav { position: fixed; top: 0; left: 0; right: 0; height: var(--nav-height); background: rgba(255, 255, 255, 0.95); backdrop-filter: blur(8px); z-index: 1000; transition: box-shadow var(--transition); }
.nav.scrolled { box-shadow: 0 1px 8px var(--color-card-shadow); }
.nav-container { max-width: var(--max-width); margin: 0 auto; padding: 0 24px; height: 100%; display: flex; align-items: center; justify-content: space-between; }
.nav-logo { font-size: 1.2rem; font-weight: 700; color: var(--color-primary); }
.nav-menu { display: flex; gap: 32px; }
.nav-link { font-size: 0.9rem; font-weight: 500; color: var(--color-text-secondary); transition: color var(--transition); position: relative; }
.nav-link:hover { color: var(--color-primary); }
.nav-toggle { display: none; flex-direction: column; gap: 5px; background: none; border: none; cursor: pointer; padding: 4px; }
.nav-toggle span { display: block; width: 22px; height: 2px; background: var(--color-text); border-radius: 2px; transition: var(--transition); }
.hero { padding-top: calc(var(--nav-height) + 80px); padding-bottom: 80px; background: linear-gradient(165deg, var(--color-primary-bg) 0%, var(--color-bg) 60%); }
.hero-content { max-width: 640px; }
.hero-greeting { font-size: 1rem; color: var(--color-text-secondary); margin-bottom: 8px; }
.hero-name { font-size: 3rem; font-weight: 700; color: var(--color-text); line-height: 1.2; margin-bottom: 12px; }
.hero-title { font-size: 1.25rem; font-weight: 600; color: var(--color-primary); margin-bottom: 20px; }
.hero-desc { font-size: 1.05rem; color: var(--color-text-secondary); line-height: 1.8; margin-bottom: 32px; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; }
.btn { display: inline-flex; align-items: center; gap: 8px; padding: 12px 24px; border-radius: var(--radius-sm); font-size: 0.95rem; font-weight: 600; transition: all var(--transition); cursor: pointer; border: 2px solid transparent; }
.btn-primary { background: var(--color-primary); color: #fff; }
.btn-primary:hover { background: var(--color-primary-dark); transform: translateY(-1px); box-shadow: 0 4px 12px rgba(37, 99, 235, 0.25); }
.btn-secondary { background: transparent; color: var(--color-primary); border-color: var(--color-primary); }
.btn-secondary:hover { background: var(--color-primary-bg); transform: translateY(-1px); }
.btn-outline { background: transparent; color: var(--color-primary); border-color: var(--color-border); }
.btn-outline:hover { border-color: var(--color-primary); background: var(--color-primary-bg); }
.btn-sm { padding: 8px 16px; font-size: 0.85rem; }
.btn-icon { width: 18px; height: 18px; }
.about-content { margin-top: 32px; }
.about-text p { margin-bottom: 16px; color: var(--color-text-secondary); font-size: 1rem; line-height: 1.9; }
.about-text p:last-child { margin-bottom: 0; }
.about-text strong { color: var(--color-text); font-weight: 600; }
.projects-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; margin-top: 32px; }
.project-card { background: var(--color-bg); border: 1px solid var(--color-border); border-radius: var(--radius); padding: 32px; transition: box-shadow var(--transition), transform var(--transition); display: flex; flex-direction: column; }
.project-card:hover { box-shadow: 0 8px 24px var(--color-card-shadow); transform: translateY(-2px); }
.project-header { display: flex; align-items: flex-start; gap: 14px; margin-bottom: 16px; }
.project-icon { flex-shrink: 0; width: 40px; height: 40px; background: var(--color-primary-bg); border-radius: var(--radius-sm); display: flex; align-items: center; justify-content: center; color: var(--color-primary); }
.project-icon svg { width: 20px; height: 20px; }
.project-title { font-size: 1.1rem; font-weight: 700; color: var(--color-text); line-height: 1.4; }
.project-desc { font-size: 0.92rem; color: var(--color-text-secondary); line-height: 1.7; margin-bottom: 16px; }
.project-highlights { margin-bottom: 24px; }
.project-highlights li { font-size: 0.88rem; color: var(--color-text-secondary); padding: 4px 0 4px 20px; position: relative; }
.project-highlights li::before { content: ''; position: absolute; left: 0; top: 12px; width: 6px; height: 6px; background: var(--color-primary); border-radius: 50%; }
.project-actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: auto; }
.proof-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; margin-top: 8px; }
.proof-card { background: var(--color-primary-bg); border-radius: var(--radius); padding: 28px 24px; text-align: center; transition: transform var(--transition); }
.proof-card:hover { transform: translateY(-2px); }
.proof-number { font-size: 2rem; font-weight: 700; color: var(--color-primary); line-height: 1.2; margin-bottom: 6px; }
.proof-label { font-size: 0.9rem; font-weight: 600; color: var(--color-text); margin-bottom: 8px; }
.proof-detail { font-size: 0.82rem; color: var(--color-text-secondary); line-height: 1.5; }
.skills-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; margin-top: 32px; }
.skill-category { background: var(--color-bg); border: 1px solid var(--color-border); border-radius: var(--radius); padding: 28px; }
.skill-category-title { display: flex; align-items: center; gap: 10px; font-size: 1rem; font-weight: 700; color: var(--color-text); margin-bottom: 16px; }
.skill-icon { width: 20px; height: 20px; color: var(--color-primary); flex-shrink: 0; }
.skill-tags { display: flex; flex-wrap: wrap; gap: 8px; }
.skill-tag { display: inline-block; padding: 5px 12px; background: var(--color-primary-bg); color: var(--color-primary); font-size: 0.82rem; font-weight: 500; border-radius: 20px; }
.contact-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-top: 32px; }
.contact-card { display: flex; flex-direction: column; align-items: center; text-align: center; background: var(--color-bg-alt); border: 1px solid var(--color-border); border-radius: var(--radius); padding: 32px 24px; transition: all var(--transition); }
.contact-card:hover { border-color: var(--color-primary); background: var(--color-primary-bg); transform: translateY(-2px); }
.contact-icon { width: 28px; height: 28px; color: var(--color-primary); margin-bottom: 12px; }
.contact-label { font-size: 0.85rem; font-weight: 600; color: var(--color-text); margin-bottom: 4px; }
.contact-value { font-size: 0.85rem; color: var(--color-text-secondary); word-break: break-all; }
.footer { padding: 32px 0; text-align: center; border-top: 1px solid var(--color-border); }
.footer p { font-size: 0.85rem; color: var(--color-text-light); }
@media (max-width: 900px) {
    .projects-grid { grid-template-columns: 1fr; }
    .proof-grid { grid-template-columns: repeat(2, 1fr); }
    .skills-grid { grid-template-columns: 1fr; }
}
@media (max-width: 768px) {
    .nav-menu { display: none; position: absolute; top: var(--nav-height); left: 0; right: 0; background: var(--color-bg); flex-direction: column; padding: 16px 24px 24px; gap: 0; box-shadow: 0 4px 12px var(--color-card-shadow); }
    .nav-menu.active { display: flex; }
    .nav-link { padding: 12px 0; font-size: 1rem; border-bottom: 1px solid var(--color-border); }
    .nav-link:last-child { border-bottom: none; }
    .nav-toggle { display: flex; }
    .nav-toggle.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
    .nav-toggle.active span:nth-child(2) { opacity: 0; }
    .nav-toggle.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }
    .hero { padding-top: calc(var(--nav-height) + 48px); padding-bottom: 48px; }
    .hero-name { font-size: 2.2rem; }
    .hero-title { font-size: 1.1rem; }
    .section { padding: 56px 0; }
    .section-title { font-size: 1.4rem; }
    .contact-grid { grid-template-columns: 1fr; }
    .proof-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 480px) {
    .hero-name { font-size: 1.8rem; }
    .hero-actions { flex-direction: column; }
    .btn { justify-content: center; width: 100%; }
    .project-card { padding: 24px; }
    .project-actions { flex-direction: column; }
    .project-actions .btn { width: 100%; justify-content: center; }
    .proof-grid { grid-template-columns: 1fr; }
}