@import url("reset.css");
@import url("variables.css");

/*
-----------------------------------------
CSS PROPERTIES & VALUES - QUICK REFERENCE
-----------------------------------------

CSS comments use /* and * / (without the space).

UNITS
px    = Pixels. Fixed CSS measurement.
%     = Percentage relative to another value,
        often the parent element.
em    = Relative to the element's font size
        (or parent's font size for font-size).
rem   = Relative to the root HTML font size.
vw    = 1% of the viewport width.
vh    = 1% of the viewport height.
ch    = Approximate width of the "0" character.

TYPOGRAPHY
font-family: Arial, sans-serif;
  Sets the typeface and fallback fonts.

font-size: 16px;
  Sets the size of the text.

font-weight: 400;
  Controls text weight.
  400 = Normal, 700 = Bold.
  Variable fonts may support values 100-900.

line-height: 1.5;
  Controls spacing between lines.
  1.5 means 1.5 times the font size.

letter-spacing: 2px;
  Controls spacing between characters.
  Negative values tighten spacing.

text-align: left;
  Aligns text: left, right, center, justify.

text-transform: uppercase;
  Changes appearance of text:
  uppercase, lowercase, capitalize, none.

COLOUR
color: #222222;
  Sets text colour.

background-color: #ffffff;
  Sets the background colour.

SPACING
margin: 20px;
  Space outside an element.

padding: 20px;
  Space inside an element.

margin-bottom: 20px;
  Adds space below an element.

WIDTH
width: 100%;
  Sets an element's width.

max-width: 800px;
  Limits how wide an element can become.

-----------------------------------------
*/


/*
03 — APPLYING VARIABLES / BASELINE BRIDGE
Numbering update: examples 01 and 02 have since been swapped at your request.
The original-number references below describe the files before that swap:
old 01 is now 02 (styled), and old 02 is now 01 (reset/reference).

The supplied example 02 has a reset and reference notes, but no typography
rules. Both originals are protected. Here we explicitly restore example 01's
basic typography and spacing, substituting variables for reusable values.
This necessary bridge is the only extra change in the colour lesson.
No grid, animation or experimental layout is introduced yet.
Try changing --font-size-h1 or --spacing-large in variables.css.
*/
body {
  background-color: var(--color-background);
  color: var(--color-text);
  font-family: var(--font-primary);
  font-size: var(--font-size-body);
  line-height: 1.6;
  padding: var(--spacing-large);
}
h1 {
  color: var(--color-primary);
  font-size: var(--font-size-h1);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -1px;
  margin-bottom: var(--spacing-medium);
}
h2 {
  color: var(--color-secondary);
  font-size: var(--font-size-h2);
  font-weight: 400;
  line-height: 1.3;
  margin-bottom: var(--spacing-heading);
}
p {
  font-size: var(--font-size-body);
  font-weight: 400;
  line-height: 1.6;
  letter-spacing: 0px;
  max-width: 650px;
  margin-bottom: var(--spacing-medium);
}
/* A long word can wrap on a narrow screen without introducing fluid sizing. */
h1, h2, p { overflow-wrap: break-word; }

/*
04 — EDITORIAL GRID
width: auto fills available space after padding. max-width caps the container
at 1280px. margin: 0 auto centres it using equal automatic side margins.
display: grid arranges direct children into tracks. repeat(3, ...) creates
three equal columns. 1fr means one share of free space; minmax(0, 1fr)
lets a column shrink below its content width. gap adds space BETWEEN tracks.
grid-column: 1 / -1 spans from the first to the last grid line.
align-items: start aligns the tops without stretching short paragraphs.
Try two columns or a larger gap. The single-column mobile lesson follows in 06.
*/
.editorial {
  width: auto;
  max-width: 1280px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--spacing-large);
  align-items: start;
}
.edition, .editorial h1, .editorial h2 { grid-column: 1 / -1; }
.edition {
  color: var(--color-secondary);
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 2px;
  border-top: 2px solid var(--color-primary);
  padding-top: var(--spacing-small);
}
.editorial > p { border-top: 1px solid var(--color-primary); padding-top: var(--spacing-medium); }

/*
05 — EXPERIMENTAL TYPE
The grid stays in place. Later rules deliberately override earlier values;
keeping earlier rules and comments makes the progression visible.
font-size increases the headline to 112px. text-shadow draws an offset copy:
3px right, 3px down, 0 blur. Try a larger offset.
-webkit-text-stroke draws a 1px outline. It is an enhancement: the green fill
remains readable without it, rather than relying on transparent letters.
transform rotates, scales and translates without moving neighbouring boxes.
rotate(-3deg) is anticlockwise; scale(1.02) is 102% of the original size;
translate(8px, -8px) moves right and up. The order of transforms matters.
transform-origin chooses the pivot. Try center instead of left center.
A negative margin creates a small overlap. position: relative allows z-index
(the stacking order) to place the chapter above the headline's shadow.
*/
h1 { font-size: 112px; text-shadow: 3px 3px 0 var(--color-secondary); }
h2 {
  transform: translate(8px, -8px) rotate(-3deg) scale(1.02);
  transform-origin: left center;
  -webkit-text-stroke: 1px var(--color-secondary);
  margin-top: -24px;
  position: relative;
  z-index: 1;
}

/*
06 — RESPONSIVE TYPOGRAPHY
1rem is the root font size (usually 16px); em follows this element's font size.
Using em for letter spacing keeps it proportional when the headline grows.
1vw / 1vh are 1% of viewport width / height. min-height: 100vh gives the page
at least a screen of height, but still allows long text to scroll.
clamp(minimum, preferred, maximum) limits fluid values. The headline uses
9vw + 1rem between 2.5rem and 9rem. Resize the browser to see it respond.
width: 100% fills the container. The inherited max-width still caps its size.
@media applies overrides only when its condition is true. At 700px and below,
three columns become one; reducing the tilt avoids clipping on small screens.
Try changing the breakpoint to 800px, or the preferred headline size to 11vw.
*/
body { padding: clamp(20px, 4vw, 64px); min-height: 100vh; }
.editorial { width: 100%; gap: clamp(20px, 3vw, 40px); }
h1 { font-size: clamp(2.5rem, 9vw + 1rem, 9rem); letter-spacing: -0.045em; }
h2 { font-size: clamp(1.5rem, 4vw, 3rem); }
p { font-size: 1rem; }
@media (max-width: 700px) {
  .editorial { grid-template-columns: minmax(0, 1fr); }
  h2 { transform: translate(0, 0) rotate(-1deg) scale(1); margin-top: 0; }
}

/*
07 — TRANSITIONS AND KEYBOARD FOCUS
A transition interpolates between two property values when a state changes.
:hover is pointer hover; :focus-visible shows keyboard focus. The anchor is a
real link to the opening paragraph, so its visual treatment has a purpose.
inline-block allows transforms on the link. Its parent retains the 05 tilt.
Only listed properties transition; duration is in seconds and the timing
function describes acceleration. Try 1s or linear in variables.css.
A large outline with an offset makes focus visible without moving the layout.
We reduce motion here too, so the first interactive stage is comfortable.
*/
.chapter-link {
  display: inline-block;
  max-width: 100%;
  color: inherit;
  text-decoration: none;
  transition: transform var(--animation-speed) var(--animation-easing),
              color var(--animation-speed) var(--animation-easing);
}
.chapter-link:hover, .chapter-link:focus-visible {
  color: var(--color-primary);
  transform: translate(4px, -4px) rotate(2deg) scale(1.02);
}
:focus-visible { outline: 3px solid var(--color-secondary); outline-offset: 6px; }
@media (prefers-reduced-motion: reduce) {
  .chapter-link { transition: none; }
  .chapter-link:hover, .chapter-link:focus-visible { transform: none; }
}

/*
08 — KEYFRAMES AND STAGGER
Transitions need a change of state; @keyframes defines its own sequence.
0%, 45%, 100% mark progress, not screen positions. Transform and opacity
move/fade the type without repeatedly calculating the document layout.
Duration is the length; delay offsets the start; iteration-count: 1 runs once.
direction: normal goes forwards (try alternate with iteration-count: 2).
fill-mode: both applies the first frame during delay and the last after ending.
The entire opening sequence is under five seconds and does not loop.
Stagger means different elements start at different times. nth-of-type counts
paragraph siblings here. Try changing .15s to .3s and watch the rhythm.
Reduced motion removes the sequence; every word stays visible and readable.
*/
/* The reset normalises every element, including spans. inherit preserves
   the existing bold headline when adding this animation wrapper. */
.kinetic-title {
  font-weight: inherit;
  display: block;
  transform-origin: left center;
  animation-name: type-drift;
  animation-duration: var(--kinetic-duration);
  animation-delay: 0s;
  animation-timing-function: ease-in-out;
  animation-iteration-count: 1;
  animation-direction: normal;
  animation-fill-mode: both;
}
.editorial > p { animation: text-enter 1s ease-out both; }
.editorial > p:nth-of-type(2) { animation-delay: .15s; }
.editorial > p:nth-of-type(3) { animation-delay: .3s; }
@keyframes type-drift {
  0%, 100% { transform: translate(0, 0) rotate(0) scale(1); opacity: 1; }
  45% { transform: translate(0, 8px) rotate(-1deg) scale(.98); opacity: .75; }
}
@keyframes text-enter {
  from { transform: translateY(18px); opacity: .4; }
  to { transform: translateY(0); opacity: 1; }
}
@media (prefers-reduced-motion: reduce) {
  .kinetic-title, .editorial > p { animation: none; }
}

/*
09 — CLASSES CONNECT JAVASCRIPT TO CSS
.js-ready stops the automatic opening sequence once controls are available.
.animate restarts the same 08 keyframes. Removing the class resets them.
.paused sets animation-play-state, freezing at the current frame until resumed.
Buttons inherit the typeface; padding enlarges their click/touch area.
Flex-wrap lets controls wrap on small screens. [hidden] must stay hidden even
when a display rule is supplied. Try different button spacing or border width.
*/
.controls {
  grid-column: 1 / -1;
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-small);
  align-items: center;
  border-top: 1px solid var(--color-primary);
  padding-top: var(--spacing-medium);
}
[hidden] { display: none !important; }
button {
  font: inherit;
  font-weight: 700;
  padding: 12px 20px;
  min-height: 48px;
  border: 2px solid var(--color-secondary);
  background: var(--color-secondary);
  color: var(--color-background);
  cursor: pointer;
  transition: background-color var(--animation-speed) var(--animation-easing),
              transform var(--animation-speed) var(--animation-easing);
}
button:hover { background-color: var(--color-primary); transform: translateY(-2px); }
#motion-status { flex-basis: 100%; font-size: .875rem; color: var(--color-text); }
.js-ready .kinetic-title, .js-ready .editorial > p { animation-name: none; }
.js-ready.animate .kinetic-title { animation-name: type-drift; }
.js-ready.animate .editorial > p { animation-name: text-enter; }
.paused .kinetic-title, .paused .editorial > p { animation-play-state: paused; }
@media (prefers-reduced-motion: reduce) {
  .js-ready.animate .kinetic-title, .js-ready.animate .editorial > p { animation: none; }
  button { transition: none; }
  button:hover { transform: none; }
}

/*
10 — DOWN THE RABBIT-HOLE / A FIVE-PART CHOREOGRAPHY
The inherited editorial grid is the starting composition. The scene above it
contains decorative text copies, never replacements for the reading content.
position: fixed pins the scene to the viewport; inset: 0 fills it. overflow:
hidden contains the travelling words without causing horizontal scrolling.
pointer-events: none lets the reading controls remain usable. Their higher
z-index keeps them in front. Controls become sticky only during the scene,
so they do not cover paragraphs while reading the initial composition.
*/
.controls {
  position: relative;
  bottom: 0;
  z-index: 30;
  padding: var(--spacing-medium);
  background: var(--color-background);
}
.falling .controls, .arrived .controls { position: sticky; }
.rabbit-hole {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 10;
  overflow: hidden;
  pointer-events: none;
  background: var(--color-background);
  color: var(--color-primary);
}
.falling .rabbit-hole, .arrived .rabbit-hole { display: block; }
/* Stage 1 (0–1.2s): the real title tilts and the scene gradually covers it.
   Opacity fades once, rather than flashing. */
.falling .rabbit-hole { animation: scene-enter 1.2s ease-in both; }
.falling .editorial h1 { animation: beginning 1.2s ease-in both; }
@keyframes beginning {
  to { transform: translate(0, 12px) rotate(3deg) scale(.96); }
}
@keyframes scene-enter { from { opacity: 0; } to { opacity: 1; } }
/* Stages 2–4: perspective is the viewer's distance from the 3D scene.
   Smaller values exaggerate depth. preserve-3d retains children's Z positions.
   translate3d(x,y,z) moves in three dimensions: negative Z recedes.
   vmin is 1% of the smaller viewport dimension, keeping the orbit on mobile.
   Each word has a deterministic angle, delay and duration supplied by JS.
   rotate + translate makes an orbit; rotateX tilts it into an ellipse.
   scale and increasingly negative Z make the spiral converge into a tunnel.
   Try 600px perspective or changing 540deg to 720deg for another half-turn.
*/
.tunnel {
  position: absolute;
  inset: 0;
  perspective: 850px;
  perspective-origin: 50% 44%;
  transform-style: preserve-3d;
}
.fragment {
  position: absolute;
  left: 50%;
  top: 44%;
  font-size: clamp(1.2rem, 4.5vw, 4.5rem);
  font-weight: 700;
  letter-spacing: -.04em;
  white-space: nowrap;
  opacity: 0;
  transform-origin: 0 0;
}
.fragment:nth-child(even) { color: var(--color-secondary); }
.fragment:nth-child(5n) { -webkit-text-stroke: 1px var(--color-text); }
.falling .fragment {
  animation: spiral var(--duration) cubic-bezier(.55, .05, .8, .5) var(--delay) both;
}
@keyframes spiral {
  0% {
    opacity: 0;
    transform: rotate(var(--angle)) translate3d(48vmin, 0, 220px) rotateX(20deg) scale(1.2);
  }
  12% { opacity: 1; }
  45% {
    opacity: 1;
    transform: rotate(calc(var(--angle) + 180deg)) translate3d(30vmin, 0, -100px) rotateX(45deg) scale(.85);
    color: var(--color-secondary);
  }
  80% { opacity: .8; color: var(--color-primary); }
  100% {
    opacity: 0;
    transform: rotate(calc(var(--angle) + 540deg)) translate3d(0, 0, -1400px) rotateX(75deg) scale(.04);
  }
}
/* Large typographic echoes form the tunnel walls, at three different depths.
   Their spacing is measured in em, so it grows along with the letters. */
.echo {
  position: absolute;
  inset: 24% -20% auto;
  text-align: center;
  font-weight: 700;
  font-size: clamp(4rem, 20vw, 20rem);
  line-height: .9;
  letter-spacing: -.08em;
  color: var(--color-primary);
  opacity: 0;
}
.echo:nth-of-type(even) { color: var(--color-secondary); }
.falling .echo { animation: tunnel-echo 6s ease-in var(--delay) both; }
@keyframes tunnel-echo {
  0% { opacity: 0; transform: translateZ(300px) rotate(-20deg); }
  15% { opacity: .2; }
  100% { opacity: 0; transform: translateZ(-1800px) rotate(160deg) scale(.1); }
}
/* Stage 5: animationend on this element tells JS the arrival has finished.
   The brief colour change is a single smooth fade, never repeated flashing. */
.arrival {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 6vw 6vw 14rem;
  background: var(--color-primary);
  color: var(--color-background);
  opacity: 0;
}
.arrival strong {
  display: block;
  font-size: clamp(2.5rem, 10vw, 10rem);
  line-height: .85;
  letter-spacing: -.07em;
  font-weight: 700;
}
.arrival-label, .arrival-foot { margin: 1.5rem 0; font-size: clamp(.75rem, 2vw, 1rem); }
.falling .arrival { animation: arrive var(--arrival-duration) ease-out var(--arrival-delay) both; }
.arrived .arrival { opacity: 1; }
@keyframes arrive {
  from { opacity: 0; transform: scale(.8) rotate(-5deg); }
  to { opacity: 1; transform: scale(1) rotate(0); }
}
/* Pause all layers together; resume continues the choreography at that point. */
.paused .rabbit-hole, .paused .fragment, .paused .echo,
.paused .arrival, .paused .editorial h1 { animation-play-state: paused; }
@media (max-width: 700px) {
  .controls { padding: 12px; gap: 8px; }
  .controls button { padding: 10px 12px; font-size: .75rem; }
  .arrival { padding-bottom: 16rem; }
}
/* Short landscape screens retain room above the controls for the arrival. */
@media (max-height: 550px) {
  .arrival { justify-content: flex-start; padding-top: 20px; }
  .arrival strong { font-size: clamp(2rem, 9vh, 4rem); }
  .arrival-label, .arrival-foot { margin: .5rem 0; }
}
@media (prefers-reduced-motion: reduce) {
  .falling .rabbit-hole, .falling .editorial h1, .falling .fragment,
  .falling .echo, .falling .arrival { animation: none; }
  .fragment, .echo { display: none; }
  .falling .arrival { opacity: 1; }
}

/*
WORKSHOP NAVIGATION — shared across the ten examples
These ordinary links open the neighbouring folder without JavaScript.
inline-block keeps the arrows beside the example number. Padding gives each
arrow a comfortable click area; currentColor follows this page's text colour.
The navigation stays in normal flow above the content, so it cannot cover it.
An outline makes keyboard focus visible. Unavailable directions are plain
spans, not links, so they cannot accidentally navigate or receive focus.
*/
.example-navigation {
  font-family: inherit;
  font-size: 14px;
  line-height: 1;
  margin-bottom: 20px;
}
.example-navigation a,
.example-navigation .unavailable {
  display: inline-block;
  padding: 12px;
  font-size: 20px;
  color: inherit;
  text-decoration: none;
}
.example-navigation a:hover { text-decoration: underline; }
.example-navigation a:focus-visible {
  outline: 2px solid currentColor;
  outline-offset: 2px;
}
.example-navigation .unavailable { opacity: .35; }
.example-navigation .example-number { font-size: 12px; }

/*
VIEWPORT FIT — examples 09 and 10
Fixed navigation stays at the top left even while the chapter scrolls.
Its z-index places it above the final animation; body padding reserves room.
On desktop, smaller fluid headings and gaps leave room for text and controls.
Height-based units also respond to shorter browser windows. We keep natural
vertical scrolling rather than clipping content or shrinking readable text.
*/
body { padding: 72px clamp(20px, 3vw, 40px) 20px; }
.example-navigation {
  position: fixed;
  top: 8px;
  left: clamp(20px, 3vw, 40px);
  z-index: 40;
  margin: 0;
  background: var(--color-background);
  color: var(--color-text);
}
.editorial { gap: clamp(12px, 2vh, 24px); }
.editorial h1 {
  font-size: clamp(2.5rem, min(6.5vw, 10vh), 6rem);
  margin-bottom: 0;
}
.editorial h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  margin-top: 0;
  margin-bottom: 0;
}
.editorial > p { margin-bottom: 0; padding-top: 12px; }
.controls { padding-top: 12px; }
@media (min-width: 1000px) {
  .editorial > p { line-height: 1.45; }
  .controls { gap: 8px; }
}
/* Scroll targets stop below the fixed navigation instead of behind it. */
#opening { scroll-margin-top: 72px; }

/* Keep the arrival below the persistent previous/next navigation. */
.arrival { padding-top: max(72px, 6vw); }
@media (max-height: 550px) {
  .arrival { padding-top: 72px; }
}

/* During the fall, hide the controls without removing their layout space.
   visibility: hidden also removes their buttons from keyboard navigation.
   The existing animationend handler removes .falling on arrival, restoring
   the controls automatically. Escape restores them if the visitor exits early. */
.falling .controls { visibility: hidden; }