/* ==================================================
   BASIC PAGE STYLES
   ================================================== */

* { box-sizing: border-box; }

body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 2rem;
  text-align: center;
  background: #f5f5f5;
  color: #111;
}

.site-header,
.page {
  max-width: 900px;
  margin: 0 auto;
}

.site-header {
  margin-bottom: 2rem;
}

.site-header p {
  max-width: 720px;
  margin: 0.75rem auto 0;
  line-height: 1.4;
}

.demo-section h2 {
  margin: 0 0 1rem;
}


/* ==================================================
   SLIDER FOUNDATION (works everywhere)
   ==================================================
   Even if “native arrows/dots” aren’t supported,
   this remains a clean scroll-snap gallery.
   ================================================== */

.slider {
  /* horizontal strip of slides */
  display: flex;
  overflow-x: auto;
  overflow-y: hidden;

  scroll-snap-type: x mandatory;
  scroll-behavior: smooth;

  /* size + centering */
  max-width: 650px;
  margin: 0 auto;
  padding: 0;  /* keep slides flush */
  gap: 0;

  /* Cosmetic */
  scrollbar-width: none; /* Firefox */
  overscroll-behavior-x: contain;

  /* Create a “frame” */
  background: white;
  border: 4px solid white;
  border-radius: 0.85rem;

  /* Cutting-edge: used by anchor-positioned arrows + dots */
  anchor-name: --slider;
}

.slider::-webkit-scrollbar { display: none; }

.slide {
  list-style: none;

  /* One slide fills the visible area */
  flex: 0 0 100%;
  scroll-snap-align: start;
  scroll-snap-stop: always;
}

.slide img {
  width: 100%;
  height: 360px;       /* TRY: 240px, 420px */
  object-fit: cover;   /* TRY: contain */
  display: block;

  border-radius: 0.6rem;
  background: white;
}


/* ==================================================
   NATIVE ARROWS (experimental CSS)
   ==================================================
   NOTE:
   - Without anchor positioning, browsers may place the
     arrows in odd locations. We only “turn on” our
     positioning rules when anchor positioning is supported.
   ================================================== */

/* Create the buttons */
.slider::scroll-button(inline-start) { content: "◀" / "Previous slide"; }
.slider::scroll-button(inline-end)   { content: "▶" / "Next slide"; }

/* Base styling (safe defaults) */
.slider::scroll-button(*) {
  inline-size: 34px;
  aspect-ratio: 1;

  display: grid;
  place-items: center;

  border-radius: 999px;
  border: 0;

  background: rgba(0, 0, 0, 0.45);
  color: white;

  cursor: pointer;
  opacity: 0.9;
}

.slider::scroll-button(*):hover {
  opacity: 1;
  background: rgba(0, 0, 0, 0.8);
}

.slider::scroll-button(*):focus {
  outline: 2px solid #111;
  outline-offset: 3px;
}

/* Optional: show disabled appearance at the ends */
.slider::scroll-button(*):disabled {
  opacity: 0.25;
  cursor: default;
}

/* ----------------------------------------------
   Upgrade: anchor positioning (pins arrows to slider)
   ---------------------------------------------- */
@supports (position-anchor: --slider) {

  .slider::scroll-button(*) {
    position: absolute;
    position-anchor: --slider;

    /* vertically center against the slider itself */
    top: anchor(center);
    transform: translateY(-50%);

    z-index: 10;
  }

  /* Place arrows just INSIDE the slider frame */
  .slider::scroll-button(inline-start) {
    left: calc(anchor(left) + 10px);
  }

  .slider::scroll-button(inline-end) {
    left: calc(anchor(right) - 34px - 10px);
  }
}


/* ==================================================
   NATIVE DOTS / MARKERS (experimental CSS)
   ==================================================
   By default, marker group appears after the slider.
   With anchor positioning support, we pin the dots
   directly under the slider so they feel “attached.”
   ================================================== */

.slider {
  /* tells the browser to generate dot UI after the slider */
  scroll-marker-group: after;
}

.slide::scroll-marker {
  content: " " / "Go to slide";

  width: 12px;
  height: 12px;
  border-radius: 999px;

  background: #bbb;
  opacity: 0.75;
  border: 0;
}

.slide::scroll-marker:hover {
  background: #666;
  opacity: 1;
}

.slide::scroll-marker:focus {
  outline: none;
}

/* Default layout (works even without anchors) */
.slider::scroll-marker-group {
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  padding: 1rem 0 0;
}

/* Anchor-position the dot row under the slider (if supported) */
@supports (position-anchor: --slider) {

  .slider::scroll-marker-group {
    position: absolute;
    position-anchor: --slider;

    /* place it 12px below the slider frame */
    top: calc(anchor(bottom) + 12px);

    /* center it under the slider */
    left: anchor(center);
    transform: translateX(-50%);

    /* remove the padding-based spacing since we're positioning it */
    padding: 0;

    z-index: 10;
  }
}

/* ==================================================
   ACTIVE DOT (when the slide is currently in view)
   ==================================================
   This is the missing piece:
   - Clicking arrows changes scroll position (not URL hash)
   - :target-current lets CSS know which marker corresponds
     to the currently visible slide
*/

.slide::scroll-marker {
  transition: background 0.2s ease, transform 0.2s ease, opacity 0.2s ease;
}

.slide::scroll-marker:target-current {
  background: #444; /* active dot color */
  opacity: 1;
  transform: scale(1.5);
}


/* ==================================================
   LESSON NOTES STYLING
   ================================================== */

.lesson-notes {
  max-width: 800px;
  margin: 8rem auto 0;
  text-align: left;
  background: white;
  padding: 1.25rem 1.5rem;
  border-radius: 1rem;
  border: 2px solid #ddd;
  line-height: 1.3;
  font-size: 1.25rem;
}

.lesson-notes code {
  font-family: ui-monospace, Consolas, "Liberation Mono", "Courier New", monospace;
  font-size: 1em;
  font-weight: bold;
}

.lesson-notes pre {
  overflow-x: auto;
  background: #f5f5f5;
  padding: 1.5rem;
  margin: 0.5rem 0 2.5rem 0;
  border-radius: 0.5rem;
  border: 1px solid #e5e5e5;
  font-size: 85%;
}

.lesson-notes h2 {
  font-size: 1.8rem;
  margin-top: 1.5rem;
  border-bottom: 1px solid silver;
  padding-bottom: 0.25rem;
  margin-bottom: 1rem;
}

.lesson-notes h2:first-of-type {
  margin-top: 0;
}

.lesson-notes h3 {
  font-size: 1.4rem;
  margin-top: 2rem;
}

.lesson-notes li {
  margin: 0.75rem 0 0.75rem 2.5rem;
}