/* ==========================================================================
   Design Portfolio Stylesheet
   - Pure CSS3, Modern Minimalist Dark Aesthetic
   ========================================================================== */

:root {
  --bg-color: #0d0f12;
  --surface-color: #16191f;
  --surface-elevated: #20242c;
  --border-color: rgba(255, 255, 255, 0.08);
  --border-active: rgba(255, 255, 255, 0.35);
  
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  
  --accent-color: #3b82f6;
  --accent-glow: rgba(59, 130, 246, 0.25);
  
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 18px;
  
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-slide: 0.5s cubic-bezier(0.25, 1, 0.5, 1);
}

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

body {
  font-family: "Pretendard", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  background-color: var(--bg-color);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* App Wrapper */
.app-container {
  max-width: 1360px;
  margin: 0 auto;
  padding: 24px 28px 40px;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* ==========================================================================
   Header Section
   ========================================================================== */
.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 30px;
  gap: 16px;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo {
  font-size: 1.35rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  background: linear-gradient(135deg, #ffffff 30%, #94a3b8 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.badge {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  padding: 2px 8px;
  border-radius: 999px;
  background-color: rgba(255, 255, 255, 0.08);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
}

.header-right {
  display: flex;
  align-items: center;
  gap: 14px;
}

/* View Mode Toggle Button Group */
.view-toggle {
  display: flex;
  background-color: var(--surface-color);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 3px;
}

.toggle-btn {
  display: flex;
  align-items: center;
  gap: 6px;
  background: transparent;
  border: none;
  color: var(--text-muted);
  padding: 7px 14px;
  border-radius: calc(var(--radius-md) - 3px);
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 500;
  transition: all var(--transition-fast);
}

.toggle-btn:hover {
  color: var(--text-primary);
}

.toggle-btn.active {
  background-color: var(--surface-elevated);
  color: var(--text-primary);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

/* PDF Download / Open Link */
.pdf-link-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background-color: var(--surface-color);
  color: var(--text-primary);
  padding: 8px 16px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  font-size: 0.85rem;
  font-weight: 500;
  text-decoration: none;
  transition: all var(--transition-fast);
}

.pdf-link-btn:hover {
  background-color: var(--surface-elevated);
  border-color: rgba(255, 255, 255, 0.2);
  transform: translateY(-1px);
}

/* ==========================================================================
   Main Content Layout
   ========================================================================== */
.main-content {
  flex: 1;
  position: relative;
}

.slider-section,
.grid-section {
  display: none;
  animation: fadeIn var(--transition-normal);
}

.slider-section.active,
.grid-section.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ==========================================================================
   Slider Viewport & Controls
   ========================================================================== */
.slider-viewport {
  position: relative;
  width: 100%;
  height: 66vh;
  min-height: 440px;
  max-height: 720px;
  background-color: var(--surface-color);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  overflow: hidden;
  box-shadow: 0 16px 40px -10px rgba(0, 0, 0, 0.6);
  user-select: none;
}

.slider-track {
  display: flex;
  height: 100%;
  transition: transform var(--transition-slide);
  will-change: transform;
}

.slide-item {
  min-width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 30px;
  position: relative;
  cursor: zoom-in;
}

.slide-item img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
  border-radius: var(--radius-sm);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
  transition: transform var(--transition-normal);
}

.slide-item:hover img {
  transform: scale(1.012);
}

/* Prev / Next Navigation Buttons */
.nav-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background-color: rgba(22, 25, 31, 0.75);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid rgba(255, 255, 255, 0.12);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  z-index: 10;
}

.prev-btn { left: 20px; }
.next-btn { right: 20px; }

.nav-btn:hover {
  background-color: rgba(32, 36, 44, 0.95);
  border-color: rgba(255, 255, 255, 0.3);
  transform: translateY(-50%) scale(1.08);
}

/* Slider Top Bar (Counter & Autoplay / Fullscreen) */
.slider-top-bar {
  position: absolute;
  top: 20px;
  left: 24px;
  right: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  z-index: 10;
  pointer-events: none;
}

.slider-top-bar > * {
  pointer-events: auto;
}

.counter {
  font-family: monospace;
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  padding: 6px 14px;
  border-radius: 999px;
  background-color: rgba(13, 15, 18, 0.7);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
}

.top-controls {
  display: flex;
  gap: 8px;
}

.icon-btn {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  background-color: rgba(13, 15, 18, 0.7);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.icon-btn:hover {
  background-color: rgba(32, 36, 44, 0.9);
  border-color: rgba(255, 255, 255, 0.25);
  transform: scale(1.06);
}

.icon-btn.active {
  color: var(--accent-color);
  border-color: var(--accent-color);
}

/* Progress Bar */
.progress-container {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 3px;
  background-color: rgba(255, 255, 255, 0.05);
  z-index: 10;
}

.progress-bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, #3b82f6, #60a5fa);
  transition: width 0.1s linear;
}

/* ==========================================================================
   Slider Bottom Info & Thumbnails
   ========================================================================== */
.slider-bottom {
  margin-top: 24px;
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 24px;
}

.slide-meta {
  padding-right: 20px;
}

.slide-title {
  font-size: 1.45rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 6px;
  color: #fff;
}

.slide-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  max-width: 600px;
}

/* Thumbnail Strip */
.thumbnail-strip {
  display: flex;
  gap: 12px;
  overflow-x: auto;
  padding: 4px;
  max-width: 480px;
  scrollbar-width: thin;
}

.thumb-item {
  width: 90px;
  height: 60px;
  flex-shrink: 0;
  border-radius: var(--radius-sm);
  overflow: hidden;
  cursor: pointer;
  border: 2px solid transparent;
  position: relative;
  background-color: var(--surface-color);
  opacity: 0.5;
  transition: all var(--transition-fast);
}

.thumb-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.thumb-item:hover {
  opacity: 0.85;
}

.thumb-item.active {
  opacity: 1;
  border-color: var(--accent-color);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px var(--accent-glow);
}

/* ==========================================================================
   Grid Gallery Section
   ========================================================================== */
.grid-container {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 28px;
  padding-bottom: 20px;
}

.grid-card {
  background-color: var(--surface-color);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  overflow: hidden;
  transition: all var(--transition-normal);
  cursor: pointer;
  display: flex;
  flex-direction: column;
}

.grid-card:hover {
  transform: translateY(-5px);
  border-color: rgba(255, 255, 255, 0.2);
  box-shadow: 0 16px 32px rgba(0, 0, 0, 0.4);
}

.grid-thumb {
  width: 100%;
  height: 280px;
  background-color: #0b0d10;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  padding: 16px;
}

.grid-thumb img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
  transition: transform var(--transition-normal);
}

.grid-card:hover .grid-thumb img {
  transform: scale(1.04);
}

.grid-info {
  padding: 18px 20px;
  border-top: 1px solid var(--border-color);
  background-color: var(--surface-color);
}

.grid-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 4px;
  color: var(--text-primary);
}

.grid-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

/* ==========================================================================
   Lightbox Modal
   ========================================================================== */
.lightbox {
  position: fixed;
  inset: 0;
  background-color: rgba(10, 12, 16, 0.94);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s ease, visibility 0.3s ease;
  padding: 30px;
}

.lightbox.active {
  opacity: 1;
  visibility: visible;
}

.lightbox-close {
  position: absolute;
  top: 24px;
  right: 24px;
  background: transparent;
  border: none;
  color: var(--text-primary);
  cursor: pointer;
  padding: 8px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform var(--transition-fast), background-color var(--transition-fast);
}

.lightbox-close:hover {
  background-color: rgba(255, 255, 255, 0.1);
  transform: rotate(90deg);
}

.lightbox-content {
  max-width: 92vw;
  max-height: 88vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.lightbox-content img {
  max-width: 100%;
  max-height: 80vh;
  object-fit: contain;
  border-radius: var(--radius-sm);
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.8);
  animation: zoomIn 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.lightbox-caption {
  margin-top: 14px;
  font-size: 1rem;
  color: var(--text-secondary);
  text-align: center;
}

@keyframes zoomIn {
  from { opacity: 0; transform: scale(0.95); }
  to { opacity: 1; transform: scale(1); }
}

/* ==========================================================================
   Footer
   ========================================================================== */
.footer {
  margin-top: 60px;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
}

.footer-info {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: var(--text-muted);
  flex-wrap: wrap;
  gap: 12px;
}

.shortcuts-guide {
  display: flex;
  gap: 14px;
}

.shortcuts-guide code {
  background-color: var(--surface-color);
  padding: 2px 6px;
  border-radius: 4px;
  border: 1px solid var(--border-color);
  font-family: inherit;
  color: var(--text-secondary);
}

/* ==========================================================================
   Responsive Breakpoints
   ========================================================================== */
@media (max-width: 900px) {
  .slider-viewport {
    height: 52vh;
    min-height: 360px;
  }
  
  .slider-bottom {
    grid-template-columns: 1fr;
    gap: 16px;
  }
  
  .thumbnail-strip {
    max-width: 100%;
  }
}

@media (max-width: 640px) {
  .app-container {
    padding: 16px 16px 32px;
  }
  
  .header {
    flex-direction: column;
    align-items: flex-start;
    gap: 14px;
  }
  
  .header-right {
    width: 100%;
    justify-content: space-between;
  }
  
  .slider-viewport {
    height: 44vh;
    min-height: 300px;
  }
  
  .slide-item {
    padding: 14px;
  }
  
  .nav-btn {
    width: 38px;
    height: 38px;
  }
  
  .prev-btn { left: 10px; }
  .next-btn { right: 10px; }
  
  .grid-container {
    grid-template-columns: 1fr;
    gap: 18px;
  }
  
  .shortcuts-guide {
    display: none;
  }
}