:root {
    --font-display: -apple-system, BlinkMacSystemFont, "Segoe UI", "Inter", system-ui, sans-serif;
    --font-body: var(--font-display);

    /* Spacing */
    --space-xs: clamp(0.5rem, 1vw, 0.75rem);
    --space-sm: clamp(0.75rem, 1.5vw, 1rem);
    --space-md: clamp(1rem, 2vw, 1.5rem);
    --space-lg: clamp(1.5rem, 3vw, 2.5rem);
    --space-xl: clamp(2rem, 4vw, 4rem);
    --space-2xl: clamp(3rem, 6vw, 6rem);
    --space-3xl: clamp(4rem, 8vw, 8rem);

    /* Radius */
    --radius-sm: 0.5rem;
    --radius-md: 1rem;
    --radius-lg: 1.5rem;
    --radius-full: 999px;
    --radius-circle: 50%;

    /* Light Mode Colors */
    --bg-primary: #FFFFFF;
    --bg-secondary: #FAFAFA;
    --bg-tertiary: #F5F5F5;
    --text-primary: #000000;
    --text-secondary: #666666;
    --text-tertiary: #999999;
    --border-color: rgba(0, 0, 0, 0.08);
    --accent-blue: #0080FF;
    --accent-cyan: #38BDF8;
    --glow-color: rgba(56, 189, 248, 0.15);

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 600ms cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    --bg-primary: #05070C;
    --bg-secondary: #0A0D12;
    --bg-tertiary: #0F131C;
    --bg-elevated: #161D2B;
    --text-primary: #FFFFFF;
    --text-secondary: #A0A0A0;
    --text-tertiary: #666666;
    --border-color: rgba(255, 255, 255, 0.08);
    --glow-color: rgba(56, 189, 248, 0.25);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    transition: background var(--transition-slow), color var(--transition-slow);
}

/* Navigation */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: background var(--transition-base), backdrop-filter var(--transition-base);
}

.nav.scrolled {
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
}

[data-theme="dark"] .nav.scrolled {
    background: rgba(5, 7, 12, 0.7);
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--space-md) var(--space-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    display: flex;
    align-items: center;
}

.logo-img {
    height: 32px;
    width: auto;
    transition: transform var(--transition-base);
}

.logo-img:hover {
    transform: scale(1.05);
}

.nav-right {
    display: flex;
    align-items: center;
    gap: var(--space-lg);
}

.nav-link {
    color: var(--text-primary);
    text-decoration: none;
    font-size: clamp(0.875rem, 1vw, 0.9375rem);
    font-weight: 500;
    letter-spacing: -0.01em;
    transition: color var(--transition-fast);
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 1px;
    background: var(--text-primary);
    transition: width var(--transition-base);
}

.nav-link:hover {
    color: var(--accent-blue);
}

.nav-link:hover::after {
    width: 100%;
}

/* Language Selector */
.lang-selector {
    background: none;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.5rem 0.75rem;
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-base);
    font-family: var(--font-body);
}

.lang-selector:hover {
    background: var(--bg-secondary);
    border-color: var(--text-tertiary);
}

.lang-selector option {
    background: var(--bg-primary);
    color: var(--text-primary);
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border-color);
    width: 36px;
    height: 36px;
    border-radius: var(--radius-full);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-base);
    position: relative;
}

.theme-toggle:hover {
    background: var(--bg-secondary);
    border-color: var(--text-tertiary);
}

.theme-icon {
    position: absolute;
    font-size: 16px;
    transition: opacity var(--transition-base), transform var(--transition-base);
}

.light-icon {
    opacity: 0;
    transform: rotate(-90deg) scale(0.5);
}

.dark-icon {
    opacity: 1;
    transform: rotate(0deg) scale(1);
}

[data-theme="dark"] .light-icon {
    opacity: 1;
    transform: rotate(0deg) scale(1);
}

[data-theme="dark"] .dark-icon {
    opacity: 0;
    transform: rotate(90deg) scale(0.5);
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    inset: 0;
    z-index: 0;
}

#particleCanvas,
#particles {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
}

.grid-overlay {
    position: absolute;
    inset: 0;
    background-image:
        linear-gradient(var(--border-color) 1px, transparent 1px),
        linear-gradient(90deg, var(--border-color) 1px, transparent 1px);
    background-size: 80px 80px;
    opacity: 0.3;
    animation: gridMove 20s linear infinite;
}

@keyframes gridMove {
    0% {
        transform: translate(0, 0);
    }
    100% {
        transform: translate(80px, 80px);
    }
}

.hero-content {
    position: relative;
    z-index: 10;
    text-align: center;
    padding: var(--space-lg);
    animation: fadeInUp 1.2s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes fadeInUp {
    0% {
        opacity: 0;
        transform: translateY(40px);
    }
    100% {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-logo-container {
    position: relative;
    display: inline-block;
    margin-bottom: var(--space-xl);
}

.hero-logo {
    height: clamp(80px, 15vw, 160px);
    width: auto;
    position: relative;
    z-index: 2;
    animation: logoFloat 6s ease-in-out infinite;
}

@keyframes logoFloat {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-10px);
    }
}

.logo-glow {
    position: absolute;
    inset: -40%;
    background: radial-gradient(circle, var(--glow-color) 0%, transparent 70%);
    z-index: 1;
    animation: pulse 4s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% {
        opacity: 0.5;
        transform: scale(1);
    }
    50% {
        opacity: 0.8;
        transform: scale(1.1);
    }
}

.hero-title {
    font-size: clamp(3rem, 12vw, 8rem);
    font-weight: 700;
    letter-spacing: -0.04em;
    margin-bottom: var(--space-md);
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: clamp(1rem, 2.5vw, 1.5rem);
    color: var(--text-secondary);
    font-weight: 400;
    letter-spacing: -0.01em;
    max-width: 600px;
    margin: 0 auto;
}

.scroll-indicator {
    position: absolute;
    bottom: var(--space-xl);
    left: 50%;
    transform: translateX(-50%);
    z-index: 10;
}

.scroll-line {
    width: 1px;
    height: 60px;
    background: linear-gradient(to bottom, var(--text-tertiary), transparent);
    animation: scrollMove 2s ease-in-out infinite;
}

@keyframes scrollMove {
    0%, 100% {
        transform: translateY(0);
        opacity: 0;
    }
    50% {
        opacity: 1;
    }
    100% {
        transform: translateY(20px);
        opacity: 0;
    }
}

/* Section */
.section {
    padding: var(--space-3xl) var(--space-lg);
    position: relative;
}

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

.section-title {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 600;
    letter-spacing: -0.03em;
    margin-bottom: var(--space-xl);
    text-align: center;
}

/* About Section */
.about-section {
    background: var(--bg-secondary);
}

.about-text {
    font-size: clamp(1.125rem, 2vw, 1.5rem);
    line-height: 1.8;
    color: var(--text-secondary);
    text-align: center;
    max-width: 900px;
    margin: 0 auto;
    letter-spacing: -0.01em;
}

/* Brand Visual Section */
.brand-visual {
    min-height: 80vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    background: var(--bg-primary);
}

.brand-letters {
    display: flex;
    gap: clamp(1rem, 3vw, 3rem);
    position: relative;
    z-index: 2;
}

.letter {
    font-size: clamp(3rem, 10vw, 10rem);
    font-weight: 700;
    letter-spacing: -0.05em;
    color: var(--text-primary);
    opacity: 0;
    transform: translateY(50px);
    animation: letterReveal 1s cubic-bezier(0.4, 0, 0.2, 1) forwards;
    transition: transform var(--transition-base), color var(--transition-base);
    cursor: default;
}

.letter:nth-child(1) { animation-delay: 0.1s; }
.letter:nth-child(2) { animation-delay: 0.2s; }
.letter:nth-child(3) { animation-delay: 0.3s; }
.letter:nth-child(4) { animation-delay: 0.4s; }
.letter:nth-child(5) { animation-delay: 0.5s; }
.letter:nth-child(6) { animation-delay: 0.6s; }

@keyframes letterReveal {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.letter:hover {
    transform: translateY(-10px) scale(1.05);
    color: var(--accent-blue);
}

.brand-lines {
    position: absolute;
    inset: 0;
    pointer-events: none;
    overflow: hidden;
}

/* Technology Section */
.technology-section {
    background: var(--bg-tertiary);
}

.tech-keywords {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--space-lg);
    max-width: 900px;
    margin: 0 auto;
}

.keyword {
    font-size: clamp(1.25rem, 3vw, 2rem);
    font-weight: 500;
    color: var(--text-secondary);
    padding: var(--space-sm) var(--space-lg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-full);
    transition: all var(--transition-base);
    letter-spacing: -0.02em;
}

.keyword:hover {
    color: var(--text-primary);
    border-color: var(--text-primary);
    transform: translateY(-2px);
    background: var(--bg-primary);
}

/* Contact Section */
.contact-section {
    min-height: 60vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-primary);
}

.contact-title {
    font-size: clamp(2.5rem, 6vw, 4rem);
    font-weight: 600;
    letter-spacing: -0.03em;
    text-align: center;
    margin-bottom: var(--space-xl);
}

.cta-button {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-xl);
    font-size: clamp(1rem, 2vw, 1.125rem);
    font-weight: 500;
    color: var(--bg-primary);
    background: var(--text-primary);
    border: none;
    border-radius: var(--radius-full);
    text-decoration: none;
    transition: all var(--transition-base);
    letter-spacing: -0.01em;
    cursor: pointer;
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
}

[data-theme="dark"] .cta-button {
    color: var(--bg-primary);
    background: var(--text-primary);
}

.arrow {
    font-size: 1.25em;
    transition: transform var(--transition-base);
}

.cta-button:hover .arrow {
    transform: translateX(4px);
}

/* Footer */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: var(--space-2xl) var(--space-lg) var(--space-lg);
}

.footer-container {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr auto;
    gap: var(--space-xl);
    align-items: center;
    margin-bottom: var(--space-xl);
}

.footer-logo {
    height: 32px;
    width: auto;
}

.footer-links {
    display: flex;
    gap: var(--space-lg);
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9375rem;
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: var(--text-primary);
}

.footer-bottom {
    max-width: 1400px;
    margin: 0 auto;
    padding-top: var(--space-lg);
    border-top: 1px solid var(--border-color);
    text-align: center;
}

.footer-bottom p {
    color: var(--text-tertiary);
    font-size: 0.875rem;
}

/* Responsive */
@media (max-width: 768px) {
    .nav-right {
        gap: var(--space-md);
    }

    .nav-link {
        font-size: 0.875rem;
    }

    .brand-letters {
        gap: clamp(0.5rem, 2vw, 1rem);
    }

    .footer-container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: var(--space-lg);
    }

    .footer-links {
        justify-content: center;
        flex-wrap: wrap;
    }
}