/* Pretendard font is loaded via <link> in index.html for performance */

:root {
  --bg-color: #0a0a0f;
  --surface-color: #141420;
  --card-bg: #1c1c2e;
  --card-hover: #252540;
  --text-primary: #F5F5F7;
  --text-secondary: #8888aa;
  --accent-blue: #4A90E2;
  --accent-pink: #FF3366;
  --accent-glow: rgba(74, 144, 226, 0.3);
  --border-subtle: rgba(255, 255, 255, 0.06);
  --delay: 0s;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Pretendard', sans-serif;
  background-color: var(--bg-color);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 8px;
}
::-webkit-scrollbar-track {
  background: var(--bg-color);
}
::-webkit-scrollbar-thumb {
  background: var(--surface-color);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--card-hover);
}

::selection {
  background-color: var(--accent-pink);
  color: #fff;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
}

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

/* Header & Nav */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  padding: 1.5rem 5%;
  z-index: 1000;
  background: rgba(10, 10, 15, 0.7);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-subtle);
  transition: all 0.3s ease;
}

.site-title {
  font-size: 1.5rem;
  font-weight: 800;
  letter-spacing: 2px;
  background: linear-gradient(135deg, var(--text-primary), var(--accent-blue), var(--accent-pink));
  background-size: 200% auto;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  animation: gradientShift 5s ease infinite;
}

.nav-links {
  display: flex;
  gap: 2rem;
}

.nav-links a {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color 0.3s ease;
  position: relative;
}

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

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent-blue);
  transition: width 0.3s ease;
}

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

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

/* Aurora / Nebula Background */
#hero::before, #hero::after {
  content: '';
  position: absolute;
  width: 60vw;
  height: 60vw;
  border-radius: 50%;
  filter: blur(80px);
  z-index: -1;
  opacity: 0.4;
  animation: aurora 15s ease-in-out infinite alternate;
}

#hero::before {
  background: radial-gradient(circle, var(--accent-blue), transparent 60%);
  top: -10%;
  left: -10%;
}

#hero::after {
  background: radial-gradient(circle, var(--accent-pink), transparent 60%);
  bottom: -20%;
  right: -10%;
  animation-delay: -5s;
}

.hero-content {
  z-index: 2;
}

.main-title {
  font-size: 4.5rem;
  font-weight: 900;
  margin-bottom: 1rem;
  background: linear-gradient(90deg, #fff, var(--text-secondary), #fff);
  background-size: 200% auto;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  animation: gradientShift 6s linear infinite;
  letter-spacing: -1px;
}

.subtitle {
  font-size: 1.2rem;
  color: var(--text-secondary);
  opacity: 0;
  animation: fadeInUp 1s cubic-bezier(0.16, 1, 0.3, 1) forwards;
  animation-delay: 0.5s;
}

/* Scroll Indicator */
.scroll-indicator {
  position: absolute;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-secondary);
  font-size: 0.8rem;
  letter-spacing: 2px;
  animation: float-subtle 3s ease-in-out infinite;
}

.scroll-arrow {
  width: 20px;
  height: 20px;
  border-bottom: 2px solid var(--text-secondary);
  border-right: 2px solid var(--text-secondary);
  transform: rotate(45deg);
  animation: bounce-arrow 2s infinite;
}

/* Portfolio Section */
#portfolio {
  padding: 6rem 5%;
  min-height: 100vh;
}

/* Category Filter Bar */
.category-filter {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 4rem;
}

.filter-btn {
  background: var(--surface-color);
  color: var(--text-secondary);
  border: 1px solid var(--border-subtle);
  padding: 0.6rem 1.5rem;
  border-radius: 50px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  font-family: inherit;
}

.filter-btn:hover {
  background: var(--card-hover);
  color: var(--text-primary);
  border-color: rgba(255, 255, 255, 0.2);
}

.filter-btn.active {
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-pink));
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 15px var(--accent-glow);
  animation: pulse-glow 2s infinite;
}

/* Masonry Grid */
.masonry-grid {
  column-count: 3;
  column-gap: 2rem;
  width: 100%;
}

/* Project Cards */
.project-card {
  background: var(--card-bg);
  border: 1px solid var(--border-subtle);
  border-radius: 16px;
  overflow: hidden;
  margin-bottom: 2rem;
  break-inside: avoid;
  cursor: pointer;
  position: relative;
  transition: all 0.5s cubic-bezier(0.16, 1, 0.3, 1);
  animation: float 6s ease-in-out infinite;
  display: flex;
  flex-direction: column;
}

/* Anti-Gravity Delays based on CSS child selectors */
.project-card:nth-child(2n) { animation-delay: -1s; }
.project-card:nth-child(3n) { animation-delay: -2.5s; }
.project-card:nth-child(4n) { animation-delay: -4s; }
.project-card:nth-child(5n) { animation-delay: -5.5s; }

.project-card:hover {
  transform: translateY(-10px) scale(1.02);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.5), 0 0 20px var(--accent-glow);
  border-color: rgba(255, 255, 255, 0.15);
  z-index: 10;
  animation-play-state: paused;
}

.card-media {
  width: 100%;
  position: relative;
  overflow: hidden;
  background: #111;
  border-radius: 16px 16px 0 0;
}

.card-media img, .card-media video {
  width: 100%;
  display: block;
  object-fit: cover;
  transition: transform 0.6s ease;
}

.project-card:hover .card-media img,
.project-card:hover .card-media video {
  transform: scale(1.05);
}

.card-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(to top, rgba(10,10,15,0.95) 0%, rgba(10,10,15,0.4) 50%, transparent 100%);
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  padding: 1.5rem;
  opacity: 0;
  transition: opacity 0.4s ease;
}

.project-card:hover .card-overlay {
  opacity: 1;
}

.card-company {
  font-size: 0.75rem;
  color: var(--accent-blue);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 0.25rem;
}

.card-title {
  font-size: 1.25rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
}

.card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.tag {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-primary);
  padding: 0.2rem 0.6rem;
  border-radius: 12px;
  font-size: 0.7rem;
  backdrop-filter: blur(4px);
  border: 1px solid rgba(255,255,255,0.05);
}

/* Card Info (Always Visible) */
.card-info {
  padding: 1.2rem 1.5rem;
}

.card-info .card-company {
  margin-bottom: 0.25rem;
}

.card-info .card-title {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
  line-height: 1.4;
}

.card-info .card-tags {
  margin-top: 0.5rem;
}

/* Scroll Reveal Animation */
.reveal {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity 0.8s cubic-bezier(0.16, 1, 0.3, 1), 
              transform 0.8s cubic-bezier(0.16, 1, 0.3, 1);
  transition-delay: var(--delay, 0s);
}

.reveal.active {
  opacity: 1;
  transform: translateY(0);
}

/* Loading Skeleton - visible by default, hidden after data loads via JS */
#loading-skeleton {
  column-count: 3;
  column-gap: 2rem;
  width: 100%;
}

.skeleton-card {
  background: var(--card-bg);
  border-radius: 16px;
  margin-bottom: 2rem;
  break-inside: avoid;
  height: 300px;
  animation: skeleton-pulse 1.5s ease-in-out infinite;
}
.skeleton-card:nth-child(even) { height: 400px; }
.skeleton-card:nth-child(3n) { height: 250px; }

/* Empty State / Error */
.message-state {
  text-align: center;
  padding: 4rem;
  color: var(--text-secondary);
  font-size: 1.1rem;
  width: 100%;
}

.message-state h3 {
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.retry-btn {
  margin-top: 1rem;
  background: var(--surface-color);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
  padding: 0.5rem 1.5rem;
  border-radius: 20px;
  cursor: pointer;
  transition: all 0.3s;
}
.retry-btn:hover { background: var(--card-hover); }

/* Detail Modal */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(10, 10, 15, 0.85);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  z-index: 9999;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 2rem;
  opacity: 0;
  visibility: hidden;
  transition: all 0.4s ease;
}

.modal-overlay.open {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  background: var(--surface-color);
  border: 1px solid var(--border-subtle);
  border-radius: 20px;
  width: 100%;
  max-width: 900px;
  max-height: 90vh;
  overflow-y: auto;
  position: relative;
  transform: scale(0.95) translateY(20px);
  opacity: 0;
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

.modal-overlay.open .modal-content {
  transform: scale(1) translateY(0);
  opacity: 1;
}

.modal-close {
  position: absolute;
  top: 1.5rem;
  right: 1.5rem;
  background: rgba(0,0,0,0.5);
  border: none;
  color: #fff;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  font-size: 1.5rem;
  cursor: pointer;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.3s;
}
.modal-close:hover { background: var(--accent-pink); }

.modal-gallery {
  position: relative;
  width: 100%;
  background: #000;
  min-height: 300px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.modal-media-item {
  display: none;
  width: 100%;
  max-height: 60vh;
  object-fit: contain;
}
.modal-media-item.active { display: block; }

.gallery-nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  background: rgba(255,255,255,0.1);
  border: none;
  color: #fff;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  cursor: pointer;
  font-size: 1.2rem;
  backdrop-filter: blur(4px);
  transition: background 0.3s;
}
.gallery-nav:hover { background: var(--accent-blue); }
.gallery-prev { left: 1rem; }
.gallery-next { right: 1rem; }

.gallery-counter {
  position: absolute;
  bottom: 1rem;
  right: 1rem;
  background: rgba(0,0,0,0.6);
  padding: 0.3rem 0.8rem;
  border-radius: 12px;
  font-size: 0.8rem;
  color: #fff;
}

.modal-body {
  padding: 2.5rem;
}

.modal-header-info {
  margin-bottom: 1.5rem;
}

.modal-company {
  color: var(--accent-blue);
  font-size: 0.85rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.modal-title {
  font-size: 2rem;
  margin-bottom: 1rem;
}

.modal-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-subtle);
}

.modal-date {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.modal-desc {
  color: var(--text-secondary);
  line-height: 1.8;
  white-space: pre-wrap;
}

/* Footer */
footer {
  text-align: center;
  padding: 3rem 0;
  border-top: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  font-size: 0.9rem;
}

/* Keyframes */
@keyframes float {
  0%, 100% { transform: translateY(0) rotate(0deg); }
  50% { transform: translateY(-8px) rotate(0.5deg); }
}

@keyframes float-subtle {
  0%, 100% { transform: translate(-50%, 0); }
  50% { transform: translate(-50%, -10px); }
}

@keyframes float-rotate {
  0%, 100% { transform: translateY(0) rotate(0deg); }
  50% { transform: translateY(-10px) rotate(1deg); }
}

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

@keyframes gradientShift {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

@keyframes pulse-glow {
  0% { box-shadow: 0 0 10px var(--accent-glow); }
  50% { box-shadow: 0 0 20px var(--accent-blue), 0 0 30px var(--accent-glow); }
  100% { box-shadow: 0 0 10px var(--accent-glow); }
}

@keyframes aurora {
  0% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(30px, -50px) scale(1.1); }
  66% { transform: translate(-20px, 20px) scale(0.9); }
  100% { transform: translate(0, 0) scale(1); }
}

@keyframes bounce-arrow {
  0%, 20%, 50%, 80%, 100% { transform: translateY(0) rotate(45deg); }
  40% { transform: translateY(-10px) rotate(45deg); }
  60% { transform: translateY(-5px) rotate(45deg); }
}

@keyframes skeleton-pulse {
  0% { background-color: var(--card-bg); }
  50% { background-color: var(--card-hover); }
  100% { background-color: var(--card-bg); }
}

/* Responsive Design */
@media (max-width: 1024px) {
  .masonry-grid, #loading-skeleton { column-count: 2; }
  .main-title { font-size: 3.5rem; }
}

@media (max-width: 640px) {
  .masonry-grid, #loading-skeleton { column-count: 1; }
  .main-title { font-size: 2.5rem; }
  header { padding: 1rem 5%; }
  .nav-links { display: none; } /* Could add hamburger menu for mobile */
  #portfolio { padding: 4rem 5%; }
  .category-filter { gap: 0.5rem; }
  .filter-btn { padding: 0.5rem 1rem; font-size: 0.85rem; }
  .modal-body { padding: 1.5rem; }
  .modal-title { font-size: 1.5rem; }
}