:root {
    --bg: #050508;
    --accent: #00f2ff;
    --accent-secondary: #ff6b9d;
    --accent-tertiary: #a855f7;
    --text: #ffffff;
    --text-secondary: rgba(255,255,255,0.6);
    --card-bg: rgba(255, 255, 255, 0.02);
    --card-border: rgba(255, 255, 255, 0.08);
    --card-hover-bg: rgba(0, 242, 255, 0.05);
    --font-main: 'Inter', -apple-system, sans-serif;
}

[data-theme="light"] {
    --bg: #fafafa;
    --accent: #0066cc;
    --accent-secondary: #cc3366;
    --accent-tertiary: #7c3aed;
    --text: #1a1a1a;
    --text-secondary: rgba(26,26,26,0.6);
    --card-bg: rgba(0, 0, 0, 0.02);
    --card-border: rgba(0, 0, 0, 0.08);
    --card-hover-bg: rgba(0, 102, 204, 0.05);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
    background: var(--bg);
    color: var(--text);
    font-family: var(--font-main);
    overflow-x: hidden;
    line-height: 1.7;
    transition: background 0.4s ease, color 0.4s ease;
}

/* 로딩 스크린 */
.loader {
    position: fixed;
    inset: 0;
    background: var(--bg);
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: opacity 0.6s ease, visibility 0.6s ease;
}
.loader.hidden { opacity: 0; visibility: hidden; pointer-events: none; }
.loader-text {
    font-size: 2rem;
    font-weight: 100;
    letter-spacing: 8px;
    color: var(--accent);
    animation: pulse 1.5s ease-in-out infinite;
}
@keyframes pulse {
    0%, 100% { opacity: 0.3; }
    50% { opacity: 1; }
}

/* 사이드 네비게이션 */
.side-nav {
    position: fixed;
    right: 30px;
    top: 50%;
    transform: translateY(-50%);
    z-index: 100;
    display: flex;
    flex-direction: column;
    gap: 16px;
}
.nav-dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    border: 1px solid var(--card-border);
    background: transparent;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
}
.nav-dot::before {
    content: attr(data-label);
    position: absolute;
    right: 24px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 0.7rem;
    letter-spacing: 2px;
    white-space: nowrap;
    opacity: 0;
    transition: opacity 0.3s ease;
    color: var(--text-secondary);
}
.nav-dot:hover::before { opacity: 1; }
.nav-dot:hover { border-color: var(--accent); }
.nav-dot.active {
    background: var(--accent);
    border-color: var(--accent);
    box-shadow: 0 0 20px var(--accent);
}

/* 테마 토글 */
.theme-toggle {
    position: fixed;
    top: 24px;
    right: 24px;
    z-index: 1000;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    color: var(--text);
    width: 44px;
    height: 44px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    backdrop-filter: blur(20px);
    overflow: hidden;
}
.theme-toggle:hover {
    border-color: var(--accent);
    transform: scale(1.1);
}
.theme-toggle svg {
    width: 20px;
    height: 20px;
    stroke: var(--text);
    stroke-width: 1.5;
    fill: none;
    transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}
.theme-toggle:hover svg {
    stroke: var(--accent);
}
.theme-toggle .sun { display: block; }
.theme-toggle .moon { display: none; }
[data-theme="light"] .theme-toggle .sun { display: none; }
[data-theme="light"] .theme-toggle .moon { display: block; }

/* DCT 캔버스 */
#dct-canvas {
    position: fixed;
    inset: 0;
    z-index: -1;
    width: 100%;
    height: 100%;
}

/* 메인 레이아웃 */
main { position: relative; z-index: 1; }

section {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding: 0 12vw;
    position: relative;
}

.label {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--accent);
    letter-spacing: 3px;
    margin-bottom: 1.5rem;
    opacity: 0;
    transform: translateX(-20px);
    transition: all 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}
section.visible .label {
    opacity: 1;
    transform: translateX(0);
}

h1 {
    font-size: clamp(4rem, 12vw, 9rem);
    font-weight: 100;
    letter-spacing: -4px;
    line-height: 0.95;
    opacity: 0;
    transform: translateY(40px);
    transition: all 1s cubic-bezier(0.16, 1, 0.3, 1) 0.1s;
}
section.visible h1 {
    opacity: 1;
    transform: translateY(0);
}

h2 {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 300;
    letter-spacing: -1px;
    margin-bottom: 1rem;
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.8s cubic-bezier(0.16, 1, 0.3, 1) 0.1s;
}
section.visible h2 {
    opacity: 1;
    transform: translateY(0);
}

.subtitle {
    max-width: 540px;
    font-size: 1.1rem;
    color: var(--text-secondary);
    font-weight: 300;
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.8s cubic-bezier(0.16, 1, 0.3, 1) 0.2s;
}
section.visible .subtitle {
    opacity: 1;
    transform: translateY(0);
}

/* 통계 컨테이너 */
.stats-container {
    display: flex;
    gap: 3rem;
    margin-top: 3rem;
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.8s cubic-bezier(0.16, 1, 0.3, 1) 0.4s;
}
section.visible .stats-container {
    opacity: 1;
    transform: translateY(0);
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    text-decoration: none;
    color: inherit;
    padding: 1rem 1.5rem;
    border: 1px solid var(--card-border);
    border-radius: 12px;
    background: var(--card-bg);
    transition: all 0.3s ease;
}
.stat-item:hover {
    border-color: var(--accent);
    background: var(--card-hover-bg);
    transform: translateY(-4px);
}
.stat-item.clickable {
    justify-content: center;
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 600;
    color: var(--accent);
    line-height: 1;
}
.stat-label {
    font-size: 0.7rem;
    letter-spacing: 2px;
    color: var(--text-secondary);
    margin-top: 0.5rem;
}
.stat-cta {
    font-size: 0.8rem;
    letter-spacing: 1px;
    color: var(--accent);
    font-weight: 500;
}

@media (max-width: 768px) {
    .stats-container {
        flex-direction: column;
        gap: 1rem;
    }
    .stat-item {
        flex-direction: row;
        align-items: center;
        gap: 1rem;
    }
    .stat-number {
        font-size: 2rem;
    }
    .stat-label {
        margin-top: 0;
    }
}

/* 스크롤 인디케이터 */
.scroll-indicator {
    position: absolute;
    bottom: 8vh;
    left: 12vw;
    display: flex;
    align-items: center;
    gap: 12px;
    opacity: 0;
    animation: fadeInUp 1s ease 1.5s forwards;
}
.scroll-line {
    width: 40px;
    height: 1px;
    background: var(--accent);
    transform-origin: left;
    animation: expandLine 1.5s ease infinite;
}
@keyframes expandLine {
    0%, 100% { transform: scaleX(0.5); opacity: 0.3; }
    50% { transform: scaleX(1); opacity: 1; }
}
.scroll-text {
    font-size: 0.7rem;
    letter-spacing: 3px;
    color: var(--text-secondary);
}
@keyframes fadeInUp {
    to { opacity: 1; }
}

/* 그리드 */
.grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
    margin-top: 3rem;
}

/* 카드 */
.card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    padding: 2rem;
    text-decoration: none;
    color: inherit;
    border-radius: 16px;
    transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    position: relative;
    overflow: hidden;
    opacity: 0;
    transform: translateY(30px);
}
.card::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, var(--accent) 0%, transparent 60%);
    opacity: 0;
    transition: opacity 0.4s ease;
}
.card:hover::before { opacity: 0.03; }
.card:hover {
    border-color: var(--accent);
    transform: translateY(-8px);
    box-shadow: 0 20px 40px rgba(0, 242, 255, 0.1);
}
section.visible .card {
    opacity: 1;
    transform: translateY(0);
}
section.visible .card:nth-child(1) { transition-delay: 0.1s; }
section.visible .card:nth-child(2) { transition-delay: 0.2s; }
section.visible .card:nth-child(3) { transition-delay: 0.3s; }
section.visible .card:nth-child(4) { transition-delay: 0.4s; }

.card h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text);
    position: relative;
}
.card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
    position: relative;
}

.tag {
    display: inline-block;
    font-size: 0.65rem;
    font-weight: 600;
    padding: 0.3rem 0.6rem;
    border-radius: 4px;
    background: var(--accent);
    color: var(--bg);
    margin-bottom: 1rem;
    letter-spacing: 1px;
}
.tag.archive { background: var(--accent-secondary); }
.tag.project { background: var(--accent-tertiary); }
.tag.research { background: #10b981; }

.card-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    position: relative;
}
.card-header .tag {
    margin-bottom: 0;
}
.live-badge {
    position: relative;
    display: inline-flex;
    align-items: center;
    gap: 4px;
    font-size: 0.65rem;
    letter-spacing: 1px;
    color: #00e676;
    font-weight: 600;
    margin-bottom: 1rem;
}
.card-header .live-badge {
    margin-bottom: 0;
}
.live-badge::before {
    content: '';
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: #00e676;
    animation: livePulse 2s ease-in-out infinite;
}
@keyframes livePulse {
    0%, 100% { opacity: 1; box-shadow: 0 0 0 0 rgba(0, 230, 118, 0.4); }
    50% { opacity: 0.7; box-shadow: 0 0 0 4px rgba(0, 230, 118, 0); }
}

.view-all-link {
    display: inline-block;
    margin-top: 2rem;
    padding: 1rem 2rem;
    border: 1px solid var(--accent);
    border-radius: 8px;
    color: var(--accent);
    text-decoration: none;
    font-size: 0.85rem;
    letter-spacing: 1px;
    transition: all 0.3s ease;
    opacity: 0;
    transform: translateY(20px);
}
section.visible .view-all-link {
    opacity: 1;
    transform: translateY(0);
    transition-delay: 0.5s;
}
.view-all-link:hover {
    background: var(--accent);
    color: var(--bg);
}

/* Expertise 카드 */
.expertise-intro {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-top: 1rem;
    line-height: 1.6;
}
.expertise-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
    margin-top: 3rem;
}
.expertise-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    padding: 2rem;
    border-radius: 16px;
    transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    opacity: 0;
    transform: translateY(30px);
}
.expertise-card:hover {
    border-color: var(--accent);
    background: var(--card-hover-bg);
}
section.visible .expertise-card {
    opacity: 1;
    transform: translateY(0);
}
section.visible .expertise-card:nth-child(1) { transition-delay: 0.1s; }
section.visible .expertise-card:nth-child(2) { transition-delay: 0.2s; }
section.visible .expertise-card:nth-child(3) { transition-delay: 0.3s; }
section.visible .expertise-card:nth-child(4) { transition-delay: 0.4s; }

.expertise-card h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--accent);
    margin-bottom: 0.75rem;
}
.expertise-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* Contact 섹션 */
#contact {
    min-height: 60vh;
}
.contact-links {
    display: flex;
    gap: 2rem;
    margin-top: 2rem;
    flex-wrap: wrap;
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.8s cubic-bezier(0.16, 1, 0.3, 1) 0.3s;
}
section.visible .contact-links {
    opacity: 1;
    transform: translateY(0);
}
.contact-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    letter-spacing: 1px;
    padding-bottom: 4px;
    border-bottom: 1px solid transparent;
    transition: all 0.3s ease;
}
.contact-link:hover {
    color: var(--accent);
    border-bottom-color: var(--accent);
}

/* Footer */
footer {
    padding: 3rem 12vw;
    border-top: 1px solid var(--card-border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.8rem;
    color: var(--text-secondary);
}
footer a {
    color: var(--accent);
    text-decoration: none;
}

/* 반응형 */
@media (max-width: 768px) {
    section { padding: 0 6vw; }
    .side-nav { display: none; }
    .grid, .expertise-grid { grid-template-columns: 1fr; }
    .scroll-indicator { left: 6vw; }
    footer {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
        padding: 2rem 6vw;
    }
    .contact-links { justify-content: center; }
}

@media (max-width: 480px) {
    h1 { letter-spacing: -2px; }
    .card, .expertise-card { padding: 1.5rem; }
}

/* ============================================
   Projects Page Styles
   ============================================ */
.projects-page {
    min-height: 100vh;
    padding: 8rem 12vw 4rem;
}
.projects-header {
    margin-bottom: 3rem;
}
.projects-header h1 {
    font-size: clamp(2.5rem, 6vw, 4rem);
    font-weight: 300;
    letter-spacing: -2px;
    margin-bottom: 1rem;
    opacity: 1;
    transform: none;
}
.projects-header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
    max-width: 600px;
}
.back-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--accent);
    text-decoration: none;
    font-size: 0.85rem;
    letter-spacing: 1px;
    margin-bottom: 2rem;
    transition: all 0.3s ease;
}
.back-link:hover {
    gap: 0.75rem;
}
.back-link svg {
    width: 16px;
    height: 16px;
    stroke: currentColor;
    stroke-width: 2;
    fill: none;
}

.filter-tabs {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}
.filter-tab {
    padding: 0.5rem 1rem;
    border: 1px solid var(--card-border);
    border-radius: 20px;
    background: transparent;
    color: var(--text-secondary);
    font-size: 0.8rem;
    letter-spacing: 1px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-family: var(--font-main);
}
.filter-tab:hover {
    border-color: var(--accent);
    color: var(--accent);
}
.filter-tab.active {
    background: var(--accent);
    border-color: var(--accent);
    color: var(--bg);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1.5rem;
}
.project-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 16px;
    padding: 2rem;
    text-decoration: none;
    color: inherit;
    transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
}
.project-card::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, var(--accent) 0%, transparent 60%);
    opacity: 0;
    transition: opacity 0.4s ease;
}
.project-card:hover::before {
    opacity: 0.03;
}
.project-card:hover {
    border-color: var(--accent);
    transform: translateY(-8px);
    box-shadow: 0 20px 40px rgba(0, 242, 255, 0.1);
}
.project-card .card-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    position: relative;
}
.project-card .tag {
    position: relative;
    width: fit-content;
}
.project-card .live-badge {
    position: relative;
    display: inline-flex;
    align-items: center;
    gap: 4px;
    font-size: 0.65rem;
    letter-spacing: 1px;
    color: #00e676;
    font-weight: 600;
}
.project-card .live-badge::before {
    content: '';
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: #00e676;
    animation: livePulse 2s ease-in-out infinite;
}
.project-card h3 {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    position: relative;
}
.project-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
    position: relative;
    flex-grow: 1;
}
.project-card .arrow {
    position: absolute;
    bottom: 1.5rem;
    right: 1.5rem;
    color: var(--accent);
    opacity: 0;
    transform: translateX(-10px);
    transition: all 0.3s ease;
}
.project-card:hover .arrow {
    opacity: 1;
    transform: translateX(0);
}

.stats-summary {
    display: flex;
    gap: 2rem;
    margin-bottom: 3rem;
    padding: 1.5rem 2rem;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    flex-wrap: wrap;
}
.stats-summary .stat {
    display: flex;
    flex-direction: column;
}
.stats-summary .stat-num {
    font-size: 2rem;
    font-weight: 600;
    color: var(--accent);
}
.stats-summary .stat-label {
    font-size: 0.7rem;
    letter-spacing: 1px;
    color: var(--text-secondary);
}

/* Projects page error fallback */
.projects-error {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-secondary);
}
.projects-error h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--text);
}
.projects-error p {
    margin-bottom: 1.5rem;
}
.projects-error button {
    padding: 0.6rem 1.5rem;
    border: 1px solid var(--accent);
    border-radius: 8px;
    background: transparent;
    color: var(--accent);
    font-family: var(--font-main);
    font-size: 0.85rem;
    letter-spacing: 1px;
    cursor: pointer;
    transition: all 0.3s ease;
}
.projects-error button:hover {
    background: var(--accent);
    color: var(--bg);
}

@media (max-width: 768px) {
    .projects-page {
        padding: 6rem 6vw 2rem;
    }
    .projects-grid {
        grid-template-columns: 1fr;
    }
    .stats-summary {
        gap: 1.5rem;
    }
}

/* ============================================
   Accessibility: Reduced Motion
   ============================================ */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    .loader {
        transition: none;
    }
    .loader-text {
        animation: none;
        opacity: 1;
    }
    #dct-canvas {
        display: none;
    }
    .scroll-indicator {
        animation: none;
        opacity: 1;
    }
    .scroll-line {
        animation: none;
        transform: scaleX(1);
        opacity: 1;
    }
    section, section .label, section h1, section h2, section .subtitle,
    section .stats-container, section .contact-links,
    .card, .expertise-card, .view-all-link {
        opacity: 1 !important;
        transform: none !important;
        transition: none !important;
    }
}