/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f7;
    --text-primary: #1d1d1f;
    --text-secondary: #86868b;
    --accent: #0066cc;
    --border: #d2d2d7;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-primary: #000000;
        --bg-secondary: #1d1d1f;
        --text-primary: #f5f5f7;
        --text-secondary: #86868b;
        --accent: #2997ff;
        --border: #424245;
    }
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 120px;
}

@media (max-width: 1024px) {
    .container {
        padding: 0 60px;
    }
}

@media (max-width: 768px) {
    .container {
        padding: 0 24px;
    }
}

/* Header & Navigation */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid var(--border);
}

@media (prefers-color-scheme: dark) {
    .header {
        background: rgba(0, 0, 0, 0.8);
    }
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 120px;
    max-width: 1200px;
    margin: 0 auto;
}

@media (max-width: 1024px) {
    .nav {
        padding: 16px 60px;
    }
}

@media (max-width: 768px) {
    .nav {
        padding: 16px 24px;
    }
}

.logo img {
    height: 60px;
    width: auto;
}

.nav-links {
    display: flex;
    gap: 32px;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-primary);
    font-size: 14px;
    font-weight: 500;
    transition: opacity 0.3s ease;
}

.nav-links a:hover {
    opacity: 0.6;
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .logo img {
        height: 40px;
    }
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 120px;
    text-align: center;
}

.hero-content {
    max-width: 900px;
}

.hero-title {
    font-size: clamp(48px, 8vw, 80px);
    font-weight: 700;
    letter-spacing: -0.03em;
    line-height: 1.05;
    margin-bottom: 32px;
}

.hero-subtitle {
    font-size: clamp(18px, 3vw, 24px);
    color: var(--text-secondary);
    font-weight: 400;
    line-height: 1.5;
    max-width: 700px;
    margin: 0 auto;
}

@media (max-width: 768px) {
    .hero {
        padding: 120px 24px 80px;
    }
}

/* Sections */
.section {
    padding: 160px 0;
}

.section-title {
    font-size: clamp(40px, 6vw, 64px);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 60px;
    text-align: center;
}

/* Thesis Section */
.thesis {
    background: var(--bg-secondary);
}

.thesis-content {
    max-width: 800px;
    margin: 0 auto;
}

.thesis-text {
    font-size: clamp(18px, 2.5vw, 22px);
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 32px;
    text-align: center;
}

.thesis-text:last-child {
    margin-bottom: 0;
}

/* Focus Section */
.focus-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
    margin-top: 80px;
}

@media (max-width: 768px) {
    .focus-grid {
        grid-template-columns: 1fr;
    }
}

.focus-card {
    padding: 48px;
    background: var(--bg-secondary);
    border-radius: 20px;
    transition: transform 0.3s ease;
}

.focus-card:hover {
    transform: translateY(-4px);
}

.focus-icon {
    margin-bottom: 24px;
    color: var(--text-primary);
}

.focus-card h3 {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 16px;
    letter-spacing: -0.01em;
}

.focus-card p {
    font-size: 16px;
    color: var(--text-secondary);
    line-height: 1.6;
}

@media (max-width: 768px) {
    .focus-card {
        padding: 32px;
    }
}

/* Portfolio Section */
.portfolio-intro {
    font-size: 20px;
    color: var(--text-secondary);
    text-align: center;
    margin-bottom: 60px;
}

.portfolio-placeholder {
    padding: 120px 48px;
    background: var(--bg-secondary);
    border-radius: 20px;
    text-align: center;
    color: var(--text-secondary);
    font-size: 18px;
}

/* Contact Section */
.contact {
    background: var(--bg-secondary);
}

.contact-intro {
    font-size: 20px;
    color: var(--text-secondary);
    text-align: center;
    margin-bottom: 60px;
}

.contact-info {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 32px;
}

.contact-link {
    font-size: clamp(24px, 4vw, 32px);
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
    transition: opacity 0.3s ease;
}

.contact-link:hover {
    opacity: 0.6;
}

.contact-social {
    display: flex;
    gap: 32px;
}

.social-link {
    font-size: 16px;
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    transition: opacity 0.3s ease;
}

.social-link:hover {
    opacity: 0.6;
}

/* Footer */
.footer {
    padding: 40px 0;
    border-top: 1px solid var(--border);
    text-align: center;
}

.footer p {
    font-size: 14px;
    color: var(--text-secondary);
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-content > * {
    animation: fadeInUp 0.8s ease-out;
}

.hero-title {
    animation-delay: 0.1s;
}

.hero-subtitle {
    animation-delay: 0.3s;
}