/* ============================================================
   style.css — ImageSlide Modern Carousel
   Light theme · Solid colors only · Pure CSS
   ============================================================ */

/* ----------------------------------------------------------
   1. CSS Custom Properties (Design Tokens)
   ---------------------------------------------------------- */
:root {
  /* Colors */
  --color-bg:          #f5f7fa;
  --color-surface:     #ffffff;
  --color-border:      #e2e8f0;
  --color-accent:      #3b82f6;
  --color-accent-dark: #2563eb;
  --color-accent-soft: #eff6ff;
  --color-text-primary:   #1e293b;
  --color-text-secondary: #64748b;
  --color-text-muted:     #94a3b8;
  --color-white:       #ffffff;

  /* Typography */
  --font-family: 'Inter', system-ui, -apple-system, sans-serif;

  /* Radii */
  --radius-sm:  6px;
  --radius-md:  12px;
  --radius-lg:  20px;
  --radius-xl:  28px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm:  0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md:  0 4px 16px rgba(0, 0, 0, 0.10);
  --shadow-lg:  0 8px 32px rgba(0, 0, 0, 0.13);
  --shadow-xl:  0 16px 48px rgba(0, 0, 0, 0.15);

  /* Spacing */
  --space-xs:  4px;
  --space-sm:  8px;
  --space-md:  16px;
  --space-lg:  24px;
  --space-xl:  40px;
  --space-2xl: 64px;

  /* Transitions */
  --slide-duration: 600ms;
  --ease-slide: cubic-bezier(0.4, 0, 0.2, 1);
  --ease-bounce: cubic-bezier(0.34, 1.56, 0.64, 1);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  background-color: var(--color-bg);
  color: var(--color-text-primary);
  line-height: 1.6;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

img {
  display: block;
  max-width: 100%;
}

button {
  cursor: pointer;
  border: none;
  background: none;
  font-family: inherit;
}

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

/* ----------------------------------------------------------
   3. Site Header
   ---------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.header-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.logo-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background-color: var(--color-accent);
  color: var(--color-white);
  border-radius: var(--radius-sm);
  font-size: 14px;
}

.logo-text {
  font-size: 18px;
  font-weight: 700;
  color: var(--color-text-primary);
  letter-spacing: -0.3px;
}

.header-nav {
  display: flex;
  gap: var(--space-lg);
}

.header-nav a {
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: color 0.2s;
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
}

.header-nav a:hover {
  color: var(--color-accent);
  background-color: var(--color-accent-soft);
}

/* ----------------------------------------------------------
   4. Hero Section
   ---------------------------------------------------------- */
.hero-section {
  text-align: center;
  padding: var(--space-2xl) var(--space-lg) var(--space-xl);
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: 800;
  letter-spacing: -1px;
  color: var(--color-text-primary);
  line-height: 1.15;
  margin-bottom: var(--space-md);
}

.hero-title .accent {
  color: var(--color-accent);
}

.hero-subtitle {
  font-size: clamp(0.95rem, 2vw, 1.1rem);
  color: var(--color-text-secondary);
  font-weight: 400;
  max-width: 480px;
  margin: 0 auto;
  letter-spacing: 0.01em;
}

/* ----------------------------------------------------------
   5. Slider Section
   ---------------------------------------------------------- */
.slider-section {
  padding: 0 var(--space-xl) var(--space-2xl);
  max-width: 980px;
  margin: 0 auto;
}

/* ----------------------------------------------------------
   6. Slider Wrapper
   ---------------------------------------------------------- */
.slider-wrapper {
  position: relative;
  width: 100%;
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-xl);
  background-color: #e2e8f0;
  aspect-ratio: 16 / 9;
  user-select: none;
}

/* ----------------------------------------------------------
   7. Loader
   ---------------------------------------------------------- */
.slider-loader {
  position: absolute;
  inset: 0;
  z-index: 20;
  background-color: var(--color-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: opacity 0.4s, visibility 0.4s;
}

.slider-loader.hidden {
  opacity: 0;
  visibility: hidden;
}

.loader-spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--color-border);
  border-top-color: var(--color-accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ----------------------------------------------------------
   8. Slide Track & Slides
   ---------------------------------------------------------- */
.slider-track {
  display: flex;
  width: 100%;
  height: 100%;
  transition: transform var(--slide-duration) var(--ease-slide);
  will-change: transform;
}

.slide {
  position: relative;
  flex: 0 0 100%;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.slide img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  transition: transform 8s ease-in-out;
}

/* Ken Burns zoom-in subtly while active */
.slide.is-active img {
  transform: scale(1.04);
}

/* ----------------------------------------------------------
   9. Slide Caption Overlay
   ---------------------------------------------------------- */
.slide-caption {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  padding: var(--space-2xl) var(--space-xl) var(--space-xl);
  background: linear-gradient(
    to top,
    rgba(15, 23, 42, 0.70) 0%,
    rgba(15, 23, 42, 0.30) 60%,
    transparent 100%
  );
  color: var(--color-white);
  transform: translateY(8px);
  opacity: 0;
  transition: transform 0.55s var(--ease-slide), opacity 0.55s var(--ease-slide);
  transition-delay: 0.18s;
}

.slide.is-active .slide-caption {
  transform: translateY(0);
  opacity: 1;
}

.caption-tag {
  display: inline-block;
  padding: 3px 12px;
  background-color: var(--color-accent);
  color: var(--color-white);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  border-radius: var(--radius-full);
  margin-bottom: var(--space-sm);
}

.caption-title {
  font-size: clamp(1.2rem, 3.5vw, 2rem);
  font-weight: 700;
  letter-spacing: -0.4px;
  line-height: 1.2;
  margin-bottom: var(--space-xs);
  text-shadow: 0 1px 4px rgba(0,0,0,0.3);
}

.caption-sub {
  font-size: clamp(0.8rem, 1.8vw, 0.95rem);
  color: rgba(255, 255, 255, 0.82);
  font-weight: 400;
  max-width: 420px;
}

/* ----------------------------------------------------------
   10. Navigation Buttons
   ---------------------------------------------------------- */
.nav-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  z-index: 10;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-full);
  background-color: var(--color-surface);
  color: var(--color-text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-md);
  transition: background-color 0.2s, transform 0.2s var(--ease-bounce), box-shadow 0.2s, opacity 0.2s;
  opacity: 0.75;
}

.nav-btn svg {
  width: 20px;
  height: 20px;
  display: block;
}

.nav-btn--prev { left: var(--space-md); }
.nav-btn--next { right: var(--space-md); }

.nav-btn:hover {
  background-color: var(--color-accent);
  color: var(--color-white);
  opacity: 1;
  transform: translateY(-50%) scale(1.08);
  box-shadow: var(--shadow-lg);
}

.nav-btn:active {
  transform: translateY(-50%) scale(0.96);
}

/* ----------------------------------------------------------
   11. Slide Counter Badge
   ---------------------------------------------------------- */
.slide-counter {
  position: absolute;
  top: var(--space-md);
  right: var(--space-md);
  z-index: 10;
  background-color: rgba(255, 255, 255, 0.92);
  color: var(--color-text-primary);
  font-size: 12px;
  font-weight: 600;
  padding: 5px 12px;
  border-radius: var(--radius-full);
  box-shadow: var(--shadow-sm);
  letter-spacing: 0.03em;
}

/* ----------------------------------------------------------
   12. Auto-Play Progress Bar
   ---------------------------------------------------------- */
.autoplay-bar {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 3px;
  background-color: rgba(255, 255, 255, 0.25);
  z-index: 10;
}

.autoplay-progress {
  height: 100%;
  width: 0%;
  background-color: var(--color-accent);
  transition: width linear;
}

/* ----------------------------------------------------------
   13. Dots Navigation
   ---------------------------------------------------------- */
.dots-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  margin-top: var(--space-xl);
}

.dot {
  width: 8px;
  height: 8px;
  border-radius: var(--radius-full);
  background-color: var(--color-border);
  border: 2px solid transparent;
  transition: background-color 0.25s, width 0.3s var(--ease-bounce), border-color 0.25s;
  padding: 0;
  outline: none;
}

.dot:hover {
  background-color: var(--color-text-muted);
}

.dot:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

.dot.active {
  width: 28px;
  background-color: var(--color-accent);
  border-color: transparent;
}

/* ----------------------------------------------------------
   14. Playback Controls
   ---------------------------------------------------------- */
.playback-controls {
  display: flex;
  justify-content: center;
  margin-top: var(--space-md);
}

.playback-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: 8px 18px;
  border-radius: var(--radius-full);
  background-color: var(--color-surface);
  color: var(--color-text-secondary);
  font-size: 13px;
  font-weight: 500;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border);
  transition: all 0.2s;
}

.playback-btn:hover {
  background-color: var(--color-accent-soft);
  color: var(--color-accent);
  border-color: var(--color-accent);
}

/* ----------------------------------------------------------
   15. Features Section
   ---------------------------------------------------------- */
.features-section {
  max-width: 980px;
  margin: 0 auto;
  padding: var(--space-xl) var(--space-xl) var(--space-2xl);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-lg);
}

.feature-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl) var(--space-lg);
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.25s, transform 0.25s var(--ease-bounce);
}

.feature-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-3px);
}

.feature-icon {
  font-size: 2rem;
  margin-bottom: var(--space-md);
}

.feature-card h3 {
  font-size: 16px;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-bottom: var(--space-sm);
}

.feature-card p {
  font-size: 13.5px;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* ----------------------------------------------------------
   16. Footer
   ---------------------------------------------------------- */
.site-footer {
  text-align: center;
  padding: var(--space-xl) var(--space-lg);
  border-top: 1px solid var(--color-border);
  background-color: var(--color-surface);
  color: var(--color-text-muted);
  font-size: 13px;
}

/* ----------------------------------------------------------
   17. Responsive
   ---------------------------------------------------------- */
@media (max-width: 768px) {
  .slider-section {
    padding: 0 var(--space-md) var(--space-2xl);
  }

  .features-section {
    padding: var(--space-xl) var(--space-md) var(--space-2xl);
  }

  .hero-section {
    padding: var(--space-xl) var(--space-md) var(--space-lg);
  }

  .nav-btn {
    width: 40px;
    height: 40px;
  }

  .nav-btn svg {
    width: 18px;
    height: 18px;
  }

  .nav-btn--prev { left: var(--space-sm); }
  .nav-btn--next { right: var(--space-sm); }

  .caption-sub {
    display: none;
  }

  .header-nav {
    display: none;
  }
}

@media (max-width: 480px) {
  .slider-wrapper {
    border-radius: var(--radius-lg);
    aspect-ratio: 4 / 3;
  }

  .slide-caption {
    padding: var(--space-xl) var(--space-md) var(--space-lg);
  }

  .features-grid {
    grid-template-columns: 1fr 1fr;
    gap: var(--space-md);
  }

  .feature-card {
    padding: var(--space-lg) var(--space-md);
  }
}

/* ----------------------------------------------------------
   18. Accessibility — Reduced Motion
   ---------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  .slider-track { transition: none; }
  .slide img { transition: none; }
  .slide-caption { transition: none; }
  .nav-btn { transition: background-color 0.15s; }
  .dot { transition: background-color 0.15s; }
  .autoplay-progress { transition: none !important; }
}