Section Curve

<section class="kodza-section-curve">
  <svg class="kodza-section-curve__edge" viewBox="0 0 1440 100" preserveAspectRatio="none" aria-hidden="true" focusable="false">
    <path d="M0 100 C300 -33.3 1140 -33.3 1440 100 Z"/>
  </svg>
  <div class="kodza-section-curve__inner">
    <h2 class="kodza-section-curve__title">The edge pulls tight as it lands.</h2>
    <p class="kodza-section-curve__text">One SVG on top of the section and a few lines of script. Scroll back up and it bends again.</p>
  </div>
</section>

/* Kodza License: free to use, client work included. Not to resell or redistribute, ported or not: https://kodza.dev/docs/#print-license */
/* Kodza — Section Curve
   A section whose top edge comes up curved and pulls flat as it lands, tied to the scroll: the
   page tightens like canvas on a frame, and bends again when you scroll back up. Without the
   script, the curve stays as it is. The colours, the depth of the curve and the room inside are
   tuned with the --kz-section-curve-* variables, the moment it is flat with the constants at the
   top of component.js, the shape with the path's d (its middle stands at the top of the box). */
.kodza-section-curve {
  --kz-section-curve-bg: #0a0a0a; /* the section, and its curve */
  --kz-section-curve-ink: #f2f2f0; /* its title */
  --kz-section-curve-muted: rgba(242, 242, 240, 0.7); /* its text */
  --kz-section-curve-depth: clamp(48px, 10vw, 160px); /* how high the middle of the curve stands */
  --kz-section-curve-pad: clamp(72px, 9vw, 136px); /* the room above and below the content */
  --kz-section-curve-width: 1080px; /* the content's widest */

  position: relative;
  box-sizing: border-box;
  display: block;
  padding: var(--kz-section-curve-pad) 24px;
  background: var(--kz-section-curve-bg);
  color: var(--kz-section-curve-ink);
}

/* The curve stands on the section's top edge, out over the section above, in the section's own
   colour; 1 px lower, so no hairline shows between the two. The script flattens it */
.kodza-section-curve__edge {
  position: absolute;
  bottom: calc(100% - 1px);
  left: 0;
  display: block;
  width: 100%;
  height: var(--kz-section-curve-depth);
  fill: var(--kz-section-curve-bg);
  pointer-events: none;
  transform: scaleY(var(--kz-section-curve-k, 1));
  transform-origin: 50% 100%;
}

/* The title on the left, the text on the right, one under the other when there is no room */
.kodza-section-curve__inner {
  display: flex;
  flex-wrap: wrap;
  gap: 24px 64px;
  align-items: flex-end;
  justify-content: space-between;
  max-width: var(--kz-section-curve-width);
  margin: 0 auto;
}

.kodza-section-curve__title {
  flex: 1 1 11em;
  max-width: 13em;
  margin: 0;
  font-family: var(--kz-font-display, inherit);
  font-size: calc(clamp(34px, 4.6vw, 64px) * var(--kz-font-display-scale, 1));
  font-weight: var(--kz-font-display-weight, 600);
  line-height: 1;
  letter-spacing: var(--kz-font-display-tracking, -0.045em);
  text-transform: var(--kz-font-display-case, inherit);
  color: inherit;
  text-wrap: balance;
}

.kodza-section-curve__text {
  flex: 0 1 24em;
  margin: 0;
  font-size: clamp(17px, 1.45vw, 20px);
  line-height: 1.5;
  color: var(--kz-section-curve-muted);
  text-wrap: pretty;
}

/* kodza-guard 096563c125e1 — generated by Kodza, do not edit.
   Theme guard: keeps a site's own CSS (WordPress themes, Bootstrap, CSS resets…) off this
   component. :not(#_) is always true and weighs as much as an id, so these lines win over
   theme rules made of classes and tags. Customise the component through its --kz-* variables. */

/* What the browser gives, on everything the component leaves to it */

.kodza-section-curve__edge:not(#_) {
  border: revert;
  margin: revert;
  padding: revert;
  border-radius: revert;
  outline: revert;
  text-decoration: revert;
  transition: revert;
  list-style: revert;
  box-sizing: revert;
  float: revert;
  background-color: revert;
  background-image: revert;
  box-shadow: revert;
  outline-offset: revert;
  appearance: revert;
  max-width: revert;
  max-height: revert;
  color: revert;
  font-family: revert;
  font-size: revert;
  font-weight: revert;
  font-style: revert;
  line-height: revert;
  letter-spacing: revert;
  text-transform: revert;
  text-underline-offset: revert;
  text-align: revert;
  text-indent: revert;
  text-shadow: revert;
  vertical-align: revert;
}

.kodza-section-curve__inner:not(#_) {
  box-sizing: revert;
}

.kodza-section-curve__title:not(#_) {
  border: revert;
  padding: revert;
  border-radius: revert;
  outline: revert;
  text-decoration: revert;
  transition: revert;
  list-style: revert;
  box-sizing: revert;
  float: revert;
  position: revert;
  background-color: revert;
  background-image: revert;
  box-shadow: revert;
  outline-offset: revert;
  appearance: revert;
  max-height: revert;
  font-style: revert;
  text-underline-offset: revert;
  text-align: revert;
  text-indent: revert;
  text-shadow: revert;
  vertical-align: revert;
}

.kodza-section-curve__text:not(#_) {
  border: revert;
  padding: revert;
  border-radius: revert;
  outline: revert;
  text-decoration: revert;
  transition: revert;
  list-style: revert;
  box-sizing: revert;
  float: revert;
  position: revert;
  background-color: revert;
  background-image: revert;
  box-shadow: revert;
  outline-offset: revert;
  appearance: revert;
  max-width: revert;
  max-height: revert;
  font-family: revert;
  font-weight: revert;
  font-style: revert;
  letter-spacing: revert;
  text-transform: revert;
  text-underline-offset: revert;
  text-align: revert;
  text-indent: revert;
  text-shadow: revert;
  vertical-align: revert;
}

.kodza-section-curve__title:not(#_):where(:not([hidden])),
.kodza-section-curve__text:not(#_):where(:not([hidden])) {
  display: revert;
}

.kodza-section-curve__title:not(#_):where([hidden]),
.kodza-section-curve__text:not(#_):where([hidden]) {
  display: none;
}

/* The component's own rules, one step stronger: real buttons and fields, what it sets on tags themes style (links, lists, headings, images…), and the root width (a theme may narrow it, never widen it) */

.kodza-section-curve__edge:not(#_) {
  position: absolute;
  display: block;
}

.kodza-section-curve__title:not(#_) {
  max-width: 13em;
  margin: 0;
  font-family: var(--kz-font-display, inherit);
  font-size: calc(clamp(34px, 4.6vw, 64px) * var(--kz-font-display-scale, 1));
  font-weight: var(--kz-font-display-weight, 600);
  line-height: 1;
  letter-spacing: var(--kz-font-display-tracking, -0.045em);
  text-transform: var(--kz-font-display-case, inherit);
  color: inherit;
}

.kodza-section-curve__text:not(#_) {
  margin: 0;
  font-size: clamp(17px, 1.45vw, 20px);
  line-height: 1.5;
  color: var(--kz-section-curve-muted);
}

// Kodza License: free to use, client work included. Not to resell or redistribute, ported or not: https://kodza.dev/docs/#print-license
// Kodza — Section Curve
// The section's top edge comes up curved and pulls flat as it lands: deepest while its top is
// low on the screen, flat once it has come up to TO, and it bends again when you scroll back up.
// The edge follows the scroll with a little give, like cloth (GLIDE). Reduced motion, or the
// site's pace at 0: the curve stays as it is. The figures you can tune are the constants below;
// the colours and the depth of the curve are in the CSS.
(() => {
  const SELECTOR = '.kodza-section-curve';
  const FROM = 1; // the curve is at its deepest while the section's top is below this share of the screen…
  const TO = 0.2; // …and flat once its top is above this one
  const GLIDE = 0.16; // how much of the way the edge catches up with the scroll each frame
  const reduceMotion = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  // The site's pace, --kz-motion-scale (set on :root, read on the instance): every duration of the
  // script times it, and 0 moves nothing, like reduced motion
  const paceOf = (el) => {
    const pace = parseFloat(getComputedStyle(el).getPropertyValue('--kz-motion-scale'));
    return pace >= 0 ? pace : 1;
  };

  // One instance, with its own state: two copies on a page never interfere. Everything it
  // starts is tied to `signal` (listeners get { signal }, the frame stops on its 'abort' event),
  // so kodza:destroy stops it all.
  function mount(root, signal) {
    const pace = paceOf(root);
    const still = reduceMotion || !pace; // the still path: no motion asked, by the visitor or the site
    if (still) return;
    let target = 1; // how curved the edge should be where the page is now, 1 to 0…
    let shown = 1; // …and how curved it is
    let frame = 0;
    let last = 0;
    const measure = () => {
      const screen = window.innerHeight;
      const top = root.getBoundingClientRect().top;
      const p = Math.min(Math.max((screen * FROM - top) / (screen * (FROM - TO)), 0), 1);
      target = 1 - p * p * (3 - 2 * p); // it starts and ends softly
    };
    const render = () => root.style.setProperty('--kz-section-curve-k', shown.toFixed(4));
    // The edge catches up GLIDE of the way each 60th of a second (more slowly at a slower pace)
    const tick = (now) => {
      const dt = last ? Math.min(now - last, 64) : 1000 / 60;
      last = now;
      shown += (target - shown) * (1 - (1 - GLIDE) ** (dt / (1000 / 60) / pace));
      if (Math.abs(target - shown) < 0.0005) {
        shown = target;
        frame = 0;
        last = 0;
      } else frame = requestAnimationFrame(tick);
      render();
    };
    const follow = () => {
      measure();
      if (!frame) frame = requestAnimationFrame(tick);
    };
    window.addEventListener('scroll', follow, { passive: true, signal });
    window.addEventListener('resize', follow, { passive: true, signal });
    // The page above can still move once its images and fonts are in
    if (document.readyState !== 'complete') window.addEventListener('load', follow, { once: true, signal });
    document.fonts?.ready.then(() => signal.aborted || follow());
    signal.addEventListener('abort', () => cancelAnimationFrame(frame));
    // On load, the edge is already where the page puts it
    measure();
    shown = target;
    render();
  }

  // Kodza lifecycle, the same in every component: `kodza:init` starts the instances inside
  // event.detail.root (the whole page by default), `kodza:destroy` stops them and puts their
  // markup back. For themes and apps that swap content without a page load. Each running root
  // keeps its markup as written under KODZA, shared by every Kodza script on the page: a Kodza
  // component inside another one is saved as written, not half-started, and stopped with it. Two
  // components on one root (a reveal on a stat card) both start, and stop together.
  const KODZA = Symbol.for('kodza');
  const RUNNING = Symbol.for(`kodza ${SELECTOR}`); // a root this component runs on, for every copy of this script
  const instances = new WeakMap();
  const find = (scope = document) => [scope, ...scope.querySelectorAll(SELECTOR)].filter((el) => el.matches?.(SELECTOR));
  const attrsOf = (el) => [...el.attributes].map((a) => [a.name, a.value]);
  const put = (el, saved) => {
    [...el.attributes].forEach((a) => el.removeAttribute(a.name));
    saved.attrs.forEach(([name, value]) => el.setAttribute(name, value));
    el.innerHTML = saved.html;
  };
  // The markup inside a root as written: Kodza components already running in it give back their own
  const written = (root) => {
    const all = [...root.querySelectorAll('*')];
    if (!all.some((el) => el[KODZA])) return root.innerHTML;
    const copy = root.cloneNode(true);
    const twins = copy.querySelectorAll('*');
    let last = null;
    all.forEach((el, i) => {
      if (!el[KODZA] || last?.contains(el)) return;
      last = el;
      put(twins[i], el[KODZA]);
    });
    return copy.innerHTML;
  };
  const init = (scope) => find(scope).forEach((root) => {
    // Already running, maybe from another copy of this script. Marked is-ready with no Kodza component
    // running on it, a root is a copy of a started one (a cloned slide): it is left as it is
    if (root[RUNNING] || (root.classList.contains('is-ready') && !root[KODZA])) return;
    // Rendered by React (data-kodza-manual): React starts it, with an init aimed at that markup once
    // it has hydrated it. Any earlier start would change markup React has not taken over yet
    const owner = root.closest('[data-kodza-manual]');
    if (owner && !(scope && owner.contains(scope))) return;
    const controller = new AbortController();
    // Another Kodza component already running on this root: its markup as written is kept, and the
    // two stop together
    const before = root[KODZA];
    const saved = { html: before ? before.html : written(root), attrs: before ? before.attrs : attrsOf(root), stop: () => destroy(root) };
    if (before) before.above = saved;
    instances.set(root, { controller, saved, before });
    root[KODZA] = saved;
    root[RUNNING] = true;
    mount(root, controller.signal);
    root.classList.add('is-ready');
  });
  const destroy = (scope) => find(scope).forEach((root) => {
    const instance = instances.get(root);
    if (!instance) return;
    instances.delete(root);
    instance.saved.above?.stop(); // a Kodza component started after it on the same root stops first
    // The Kodza components running inside it stop first: once its markup is put back, their own
    // script could not find them any more
    root.querySelectorAll('*').forEach((el) => el[KODZA]?.stop());
    instance.controller.abort();
    delete root[RUNNING];
    // Started on top of another one: that one stops next, and puts the markup back
    if (instance.before) {
      delete instance.before.above;
      root[KODZA] = instance.before;
      return instance.before.stop();
    }
    delete root[KODZA];
    put(root, instance.saved);
  });
  document.addEventListener('kodza:init', (event) => init(event.detail?.root));
  document.addEventListener('kodza:destroy', (event) => destroy(event.detail?.root));
  init();
  // Loaded in <head>, the script runs before the markup exists: once more when it is parsed
  if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', () => init(), { once: true });
})();

'use client';
// Kodza — Section Curve, for React. From https://kodza.dev/components/section-curve/
// Kodza License: free to use, client work included. Not to resell or redistribute, ported or not: https://kodza.dev/docs/#print-license
// Next to this file: section-curve.css and section-curve.js, the component's CSS and JS from Kodza, as they are.
// Yours to edit: the markup is plain JSX below.
// The script changes this markup once React has rendered it (it adds layers, splits text, moves
// nodes), so React must not patch it afterwards. When a prop changes, the key gives React a fresh
// element: kodza:destroy stops the script on the old one, kodza:init starts it on the new one.
// data-kodza-manual keeps the script from starting it on its own: the effect below does, once
// React has hydrated the markup (on a page that streams in, the script can load first).
// Built from your data (tabs, rows, options)? Put what the markup is made of in the key, as plain
// values (ids, text, numbers): a change starts the script again on fresh markup. What the visitor
// changes (the open tab, the sort, what they type) is the script's: keep it out of the key, follow
// it with onClick or onInput on the root, and change it from your code as a visitor would (click
// the tab; set the field's value, then dispatch a bubbling input event).
import { useRef, useEffect, type ComponentPropsWithoutRef, type ComponentRef, type CSSProperties } from 'react';
import './section-curve.css';

export type SectionCurveProps = Omit<ComponentPropsWithoutRef<'section'>, "children" | "vars"> & {
  /** Settings, as CSS variables on the root */
  vars?: {
    /** the section, and its curve — default: #0a0a0a */
    "--kz-section-curve-bg"?: string | number;
    /** its title — default: #f2f2f0 */
    "--kz-section-curve-ink"?: string | number;
    /** its text — default: rgba(242, 242, 240, 0.7) */
    "--kz-section-curve-muted"?: string | number;
    /** how high the middle of the curve stands — default: clamp(48px, 10vw, 160px) */
    "--kz-section-curve-depth"?: string | number;
    /** the room above and below the content — default: clamp(72px, 9vw, 136px) */
    "--kz-section-curve-pad"?: string | number;
    /** the content's widest — default: 1080px */
    "--kz-section-curve-width"?: string | number;
  };
  className?: string;
};

export function SectionCurve({ vars, className, style, ...rest }: SectionCurveProps) {
  const ref = useRef<ComponentRef<'section'>>(null);
  const classes = ["kodza-section-curve", className].filter(Boolean).join(' ');
  // Everything the markup is made of: when it changes, React gets a fresh element (see the top)
  const key = JSON.stringify([classes, vars, style, rest]);

  // Starts the script on this element once React has rendered it, stops it when it goes
  useEffect(() => {
    const root = ref.current;
    let live = true;
    // @ts-ignore: a plain script, no types to find
    import('./section-curve.js').then(() => {
      if (live) document.dispatchEvent(new CustomEvent('kodza:init', { detail: { root } }));
    });
    return () => {
      live = false;
      document.dispatchEvent(new CustomEvent('kodza:destroy', { detail: { root } }));
    };
  }, [key]);

  return (
    <section key={key} {...rest} className={classes} data-kodza-manual style={{ ...vars, ...style } as CSSProperties} ref={ref}>
      <svg className="kodza-section-curve__edge" viewBox="0 0 1440 100" preserveAspectRatio="none" aria-hidden="true" focusable="false">
        <path d="M0 100 C300 -33.3 1140 -33.3 1440 100 Z" />
      </svg>
      <div className="kodza-section-curve__inner">
        <h2 className="kodza-section-curve__title">The edge pulls tight as it lands.</h2>
        <p className="kodza-section-curve__text">One SVG on top of the section and a few lines of script. Scroll back up and it bends again.</p>
      </div>
    </section>
  );
}