/* ============================================================
   DESIGN TOKENS
   ============================================================ */
:root {
  --white: #FFFFFF;
  --snow: #FAFBFC;
  --ash: #F2F3F5;
  --mist: #E8EAED;
  --smoke: #C4C8CF;
  --slate: #8A8F98;
  --graphite: #5C6370;
  --ink: #1A1D23;
  --blue-pale: #EDF2FF;
  --blue-light: #B4C6FC;
  --blue: #4A6CF7;
  --blue-deep: #2A4AD4;
  --blue-ink: #1B2F80;

  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --fs-xs: 0.70rem;
  --fs-sm: 0.8125rem;
  --fs-base: 0.9375rem;
  --fs-lg: 1.125rem;

  --ease: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-out: cubic-bezier(0, 0, 0.15, 1);
  --dur-fast: 180ms;
  --dur: 320ms;
  --dur-slow: 600ms;
  --dur-swipe: 700ms;

  --content-max: 1440px;
  --content-pad-x: 3rem;
}


/* ============================================================
   RESET & BASE
   ============================================================ */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
}

html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  overflow: hidden;
  overscroll-behavior: none;
  width: 100%;
  height: 100%;
}

body {
  font-family: var(--font);
  font-size: var(--fs-base);
  color: var(--ink);
  background: var(--white);
  overflow: hidden;
  overscroll-behavior: none;
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  line-height: 1.6;
}

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


/* ============================================================
   CANVAS BACKGROUND
   ============================================================ */
#bg-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
}


/* ============================================================
   FILM GRAIN OVERLAY
   ============================================================ */
.grain-overlay {
  position: fixed;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  z-index: 1;
  pointer-events: none;
  opacity: 0.022;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  background-size: 256px 256px;
}


/* ============================================================
   CONTENT LAYER
   ============================================================ */
.content-layer {
  position: relative;
  z-index: 2;
  height: 100%;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}


/* ============================================================
   HEADER / NAV
   ============================================================ */
.site-header {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: min(100%, calc(var(--content-max) + 2 * var(--content-pad-x)));
  margin-inline: auto;
  padding: 1.5rem var(--content-pad-x);
  background: transparent;
  pointer-events: auto;
  opacity: 0;
  transform: translateY(-12px);
  animation: fade-down 0.8s var(--ease-out) 0.15s forwards;
}

.site-header .header-back,
.site-header .header-title,
.site-header .header-counter {
  text-shadow:
    0 0 10px #fff,
    0 0 4px #fff,
    0 1px 2px #fff;
}

.header-back {
  font-size: var(--fs-sm);
  font-weight: 450;
  color: var(--slate);
  letter-spacing: 0.05em;
  text-transform: uppercase;
  border-bottom: 1px solid transparent;
  padding-bottom: 2px;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.header-back:hover {
  color: var(--ink);
  border-color: var(--ink);
}

.header-title {
  font-family: "Russo One", sans-serif;
  font-size: 1.05rem;
  font-weight: 400;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.header-counter {
  font-size: var(--fs-sm);
  font-weight: 450;
  color: var(--slate);
  letter-spacing: 0.04em;
  font-variant-numeric: tabular-nums;
  min-width: 3.5rem;
  text-align: right;
}


/* ============================================================
   SLIDES CONTAINER — native scroll-snap
   ============================================================ */
.slides-container {
  flex: 1;
  min-height: 0;
  overflow-y: scroll;
  scroll-snap-type: y mandatory;
  scroll-behavior: smooth;
  overscroll-behavior: none;
  /* Thin styled scrollbar */
  scrollbar-width: thin;
  scrollbar-color: var(--smoke) transparent;
}

.slides-container::-webkit-scrollbar {
  width: 3px;
}

.slides-container::-webkit-scrollbar-track {
  background: transparent;
}

.slides-container::-webkit-scrollbar-thumb {
  background: var(--smoke);
  border-radius: 2px;
  transition: background 0.2s;
}

.slides-container::-webkit-scrollbar-thumb:hover {
  background: var(--slate);
}

.slide {
  width: 100%;
  height: 100%;
  /* or 100vh if container is flexible, 100% works if parent is fixed */
  flex-shrink: 0;
  scroll-snap-align: start;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem var(--content-pad-x);
  /* consistent padding around the slide */
}

/* Layout: text left-center, image right-bottom */
.slide-inner {
  width: 100%;
  max-width: var(--content-max);
  height: 100%;
  min-height: 0;
  /* prevent grid blow-out */
  padding: 0;
  /* padding is handled by .slide */
  display: grid;
  grid-template-columns: 1fr 1fr;
  grid-template-rows: minmax(0, 1fr);
  /* CRITICAL: prevents grid from expanding beyond 100% */
  align-items: center;
  gap: 4rem 6rem;
}

.slide-text {
  align-self: start;
  height: 100%;
  /* tightly bind to grid cell height */
  min-height: 0;
  /* CRITICAL: prevents flex container from blowing out the grid */
  margin-top: 0;
  padding-top: 10vh;
  /* 25% space above title as requested */
  padding-bottom: 10vh;
  /* 10% space at bottom as requested */
  display: flex;
  flex-direction: column;
}

.slide-image {
  align-self: center;
  min-height: 0;
  max-height: 100%;
  overflow: hidden;
  margin-top: 5vh;
  /* slightly below center */
  padding-top: 0;
  padding-bottom: 0;
}

/* Board number label */
.slide-index {
  font-size: var(--fs-xs);
  font-weight: 500;
  color: var(--blue);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 1.1rem;
  opacity: 0.8;
}

.slide-title {
  font-family: "Russo One", sans-serif;
  font-size: clamp(1.4rem, 2.6vw, 2.1rem);
  font-weight: 400;
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--ink);
  margin-bottom: 1.4rem;
}

.slide-title a {
  color: inherit;
  text-decoration: none;
  transition: color var(--dur) var(--ease);
}

.slide-title a:hover {
  color: var(--blue-deep);
}

.slide-desc {
  font-size: clamp(0.82rem, 1.1vw, 0.9375rem);
  font-weight: 400;
  color: var(--graphite);
  line-height: 1.72;

  flex: 1;
  /* take all remaining space within .slide-text */
  min-height: 0;
  max-height: none;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding-right: 1rem;

  scrollbar-width: thin;
  scrollbar-color: var(--smoke) transparent;
}

/* Fade edges when text overflows — same 5% soft mask as board images */
.slide-desc.fade-top {
  -webkit-mask-image: linear-gradient(to bottom, transparent 0%, black 5%, black 100%);
  mask-image: linear-gradient(to bottom, transparent 0%, black 5%, black 100%);
}

.slide-desc.fade-bottom {
  -webkit-mask-image: linear-gradient(to bottom, black 0%, black 95%, transparent 100%);
  mask-image: linear-gradient(to bottom, black 0%, black 95%, transparent 100%);
}

.slide-desc.fade-top.fade-bottom {
  -webkit-mask-image: linear-gradient(to bottom, transparent 0%, black 5%, black 95%, transparent 100%);
  mask-image: linear-gradient(to bottom, transparent 0%, black 5%, black 95%, transparent 100%);
}

.slide-desc::-webkit-scrollbar {
  width: 3px;
}

.slide-desc::-webkit-scrollbar-track {
  background: transparent;
}

.slide-desc::-webkit-scrollbar-thumb {
  background: var(--smoke);
  border-radius: 2px;
  transition: background 0.2s;
}

.slide-desc::-webkit-scrollbar-thumb:hover {
  background: var(--slate);
}

.slide-image img {
  width: 100%;
  max-width: 560px;
  height: auto;
  max-height: 75vh;
  object-fit: contain;
  border-radius: 0;
  display: block;
  box-shadow: none;
  transition: transform 0.5s var(--ease);

  /* Fade to transparent 5% at the edges using intersecting linear gradients */
  -webkit-mask-image: linear-gradient(to right, transparent 0%, black 5%, black 95%, transparent 100%),
    linear-gradient(to bottom, transparent 0%, black 5%, black 95%, transparent 100%);
  -webkit-mask-composite: source-in;
  mask-image: linear-gradient(to right, transparent 0%, black 5%, black 95%, transparent 100%),
    linear-gradient(to bottom, transparent 0%, black 5%, black 95%, transparent 100%);
  mask-composite: intersect;
}

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

/* No-image placeholder */
.slide-no-image {
  width: 100%;
  max-width: 560px;
  aspect-ratio: 4/3;
  border-radius: 0;
  background: transparent;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
}

.slide-no-image svg {
  opacity: 0.12;
  width: 64px;
  height: 64px;
}


/* ============================================================
   PROGRESS DOTS — vertical strip on the right
   ============================================================ */
.progress-dots {
  position: fixed;
  right: 1.5rem;
  top: 50%;
  transform: translateY(-50%);
  z-index: 20;
  display: flex;
  flex-direction: column;
  gap: 6px;
  align-items: center;
  pointer-events: none;
  opacity: 0;
  animation: fade-up 0.8s var(--ease-out) 0.9s forwards;
}

.dot {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--smoke);
  transition: all 0.4s var(--ease);
}

.dot.active {
  background: var(--blue);
  height: 18px;
  border-radius: 3px;
}


/* ============================================================
   GLOBAL SOCIAL LINKS — bottom right (under image)
   ============================================================ */
.global-social-links {
  position: fixed;
  bottom: 2rem;
  left: 0;
  right: 0;
  width: max-content;
  margin-inline: auto;
  z-index: 20;
  display: flex;
  gap: 2rem;
  animation: fade-up 0.8s var(--ease-out) 1.2s both;
}


/* ============================================================
   NAV ARROWS — vertical pair on the right
   ============================================================ */
.nav-arrows {
  position: fixed;
  right: 1.5rem;
  bottom: 2.5rem;
  z-index: 20;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  pointer-events: auto;
  opacity: 0;
  animation: fade-up 0.8s var(--ease-out) 1s forwards;
}

.nav-arrow {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: 1px solid var(--mist);
  background: rgba(255, 255, 255, 0.6);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition:
    background var(--dur-fast) var(--ease),
    border-color var(--dur-fast) var(--ease),
    transform var(--dur-fast) var(--ease);
}

.nav-arrow:hover {
  background: var(--white);
  border-color: var(--smoke);
  transform: scale(1.08);
}

.nav-arrow:active {
  transform: scale(0.94);
}

.nav-arrow svg {
  width: 14px;
  height: 14px;
  stroke: var(--graphite);
  stroke-width: 1.8;
  fill: none;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.nav-arrow.disabled {
  opacity: 0.25;
  pointer-events: none;
}


/* ============================================================
   SLIDE ENTRANCE ANIMATION — directional scroll
   ============================================================ */
.slide-text,
.slide-image {
  opacity: 0;
}

/* Scrolling down (default direction) */
.slide.in-view-down .slide-text {
  animation: slide-text-in-down 0.8s var(--ease-out) 0.05s both;
}

.slide.in-view-down .slide-image {
  animation: slide-img-in-down 1.1s cubic-bezier(0.2, 1.2, 0.4, 1) 0.25s both;
}

/* Scrolling up (reverse direction) */
.slide.in-view-up .slide-text {
  animation: slide-text-in-up 0.8s var(--ease-out) 0.05s both;
}

.slide.in-view-up .slide-image {
  animation: slide-img-in-up 1.1s cubic-bezier(0.2, 1.2, 0.4, 1) 0.25s both;
}

@keyframes slide-text-in-down {
  from {
    opacity: 0;
    transform: translateY(20px);
  }

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

@keyframes slide-text-in-up {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }

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

@keyframes slide-img-in-down {
  from {
    opacity: 0;
    transform: translateY(40px);
  }

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

@keyframes slide-img-in-up {
  from {
    opacity: 0;
    transform: translateY(-40px);
  }

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


/* ============================================================
   ENTRANCE ANIMATIONS
   ============================================================ */
@keyframes fade-up {
  from {
    opacity: 0;
    transform: translateY(16px);
  }

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

@keyframes fade-down {
  from {
    opacity: 0;
    transform: translateY(-12px);
  }

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


/* ============================================================
   ULTRA-WIDE — keep text vertically with the image
   ============================================================ */
@media (min-width: 1600px) {
  .slide-text {
    align-self: center;
    height: auto;
    max-height: 100%;
    padding-top: 0;
    padding-bottom: 0;
  }

  .slide-image {
    margin-top: 0;
  }
}


/* ============================================================
   MOBILE LANDSCAPE — compact side-by-side
   ============================================================ */
@media (max-height: 540px) and (orientation: landscape) {
  .site-header {
    padding: 0.75rem 1.5rem;
  }

  .slide {
    padding: 0 1.5rem 1rem;
  }

  .slide-inner {
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem 2.5rem;
    align-items: center;
  }

  .slide-text {
    align-self: center;
    padding-bottom: 0;
  }

  .slide-image {
    align-self: center;
    padding-top: 0;
  }

  .slide-title {
    font-size: clamp(1rem, 3.5vw, 1.3rem);
    margin-bottom: 0.6rem;
  }

  .slide-desc {
    font-size: clamp(0.72rem, 1.6vw, 0.82rem);
    line-height: 1.55;
  }

  .slide-image img,
  .slide-no-image {
    max-width: 100%;
    aspect-ratio: 4/3;
  }

  .nav-arrows {
    bottom: 0.75rem;
    right: 1rem;
  }

  .nav-arrow {
    width: 30px;
    height: 30px;
  }

  .progress-dots {
    right: 1rem;
  }
}


/* ============================================================
   MOBILE PORTRAIT — image top third, text below
   ============================================================ */
@media (max-width: 700px) and (orientation: portrait) {
  .site-header {
    width: 100%;
    padding: 1.1rem 1.25rem;
    background: transparent;
  }

  .slide {
    padding: 3.25rem 1.25rem 1rem; /* top: room under transparent header */
    align-items: stretch;
  }

  .slide-inner {
    grid-template-columns: 1fr;
    grid-template-rows: minmax(0, 33vh) minmax(0, 1fr);
    gap: 1rem;
    align-items: stretch;
    height: 100%;
    min-height: 0;
    overflow: hidden;
  }

  .slide-image {
    grid-row: 1;
    z-index: 0;
    height: 100%;
    max-height: 100%;
    overflow: hidden;
    padding-top: 0;
    margin-top: 0;
    align-self: stretch;
    min-height: 0;
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .slide-text {
    grid-row: 2;
    z-index: 1;
    align-self: stretch;
    height: 100%;
    min-height: 0;
    margin-top: 0;
    padding-top: 0;
    padding-bottom: 4.5rem; /* room for social links */
  }

  .slide-desc {
    max-height: none;
    font-size: clamp(0.78rem, 3.2vw, 0.88rem);
    line-height: 1.62;
    max-width: none;
  }

  .slide-image img,
  .slide-no-image {
    max-width: 100%;
    width: auto;
    height: auto;
    max-height: 100%;
    object-fit: contain;
    border-radius: 0;
  }

  .slide-title {
    font-size: clamp(1.1rem, 5.5vw, 1.5rem);
    margin-bottom: 0.75rem;
  }

  .global-social-links {
    bottom: 1.25rem;
    gap: 1.25rem;
  }

  .progress-dots {
    right: 0.75rem;
  }

  .nav-arrows {
    display: none;
  }
}


/* ============================================================
   TABLET
   ============================================================ */
@media (min-width: 701px) and (max-width: 1024px) and (orientation: portrait) {
  .slide-inner {
    grid-template-columns: 1fr;
    gap: 2rem;
    align-items: center;
  }

  .slide-image {
    grid-row: 1;
    padding-top: 0;
  }

  .slide-text {
    grid-row: 2;
    padding-bottom: 3rem;
  }

  .slide-image img,
  .slide-no-image {
    max-width: 100%;
    height: auto;
    max-height: 50vh;
    object-fit: contain;
  }
}