Add styled legal dialogs with unchanged supplied content

assets/legal.mjs

@@ -0,0 +1,83 @@
+const dialogs = new Map(
+  [...document.querySelectorAll('.legal-dialog')].map(dialog => [dialog.id, dialog]),
+);
+let returnFocus;
+
+function syncDialog() {
+  const next = dialogs.get(location.hash.slice(1));
+  let closed = false;
+
+  for (const dialog of dialogs.values()) {
+    if (dialog.open && dialog !== next) {
+      dialog.close();
+      closed = true;
+    }
+  }
+
+  if (next && !next.open) {
+    returnFocus ??= document.querySelector(`[data-legal-open][aria-controls="${next.id}"]`);
+    next.showModal();
+    next.querySelector('.legal-copy').scrollTop = 0;
+    next.querySelector('h1').focus({ preventScroll: true });
+  } else if (!next && closed) {
+    returnFocus?.focus({ preventScroll: true });
+    returnFocus = undefined;
+  }
+}
+
+function dismissDialog() {
+  history.replaceState(null, '', location.pathname + location.search);
+  syncDialog();
+}
+
+for (const link of document.querySelectorAll('[data-legal-open]')) {
+  link.addEventListener('click', event => {
+    if (event.button !== 0 || event.metaKey || event.ctrlKey || event.shiftKey || event.altKey) return;
+    event.preventDefault();
+    returnFocus = link;
+    history.pushState(null, '', link.hash);
+    syncDialog();
+  });
+}
+
+for (const dialog of dialogs.values()) {
+  dialog.querySelector('[data-legal-close]').addEventListener('click', event => {
+    event.preventDefault();
+    dismissDialog();
+  });
+  dialog.addEventListener('cancel', event => {
+    event.preventDefault();
+    dismissDialog();
+  });
+  dialog.addEventListener('keydown', event => {
+    if (event.key !== 'Tab' || event.altKey || event.ctrlKey || event.metaKey) return;
+    const controls = [...dialog.querySelectorAll('a[href], button:not([disabled]), [tabindex="0"]')];
+    const first = controls[0];
+    const last = controls.at(-1);
+    const active = document.activeElement;
+    if (!controls.includes(active) || (event.shiftKey && active === first)
+      || (!event.shiftKey && active === last)) {
+      event.preventDefault();
+      (event.shiftKey ? last : first)?.focus();
+    }
+  });
+
+  // Close only when both ends of a click are on the backdrop, not a text-selection drag.
+  let startedOutside = false;
+  const outside = event => {
+    const rect = dialog.getBoundingClientRect();
+    return event.clientX < rect.left || event.clientX > rect.right
+      || event.clientY < rect.top || event.clientY > rect.bottom;
+  };
+  dialog.addEventListener('pointerdown', event => {
+    startedOutside = event.target === dialog && outside(event);
+  });
+  dialog.addEventListener('click', event => {
+    if (startedOutside && event.target === dialog && outside(event)) dismissDialog();
+    startedOutside = false;
+  });
+}
+
+window.addEventListener('hashchange', syncDialog);
+window.addEventListener('popstate', syncDialog);
+syncDialog();

assets/styles.css

@@ -22,6 +22,10 @@
   --color-sand: #e5cd9c;
   --color-announcement: #f2e6cc;
   --color-focus: #ffc300;
+  --color-accent: #ef3a57;
+  --color-dialog: #721a3d;
+  --color-overlay: rgb(24 8 16 / 72%);
+  --color-shadow: rgb(24 8 16 / 45%);
   /* One design unit is one point on the supplied 1200 × 900 layout. */
   --unit: 0.0833333333vw;
   --font-body: Roboto, system-ui, sans-serif;
@@ -284,6 +288,166 @@ address {
   transform: none;
 }
 
+.site-footer {
+  margin-block-start: 28px;
+  border-block-start: 1px solid color-mix(in srgb, var(--color-sand) 35%, transparent);
+  padding-block-start: 8px;
+  color: var(--color-sand);
+  font-size: 14px;
+}
+
+.site-footer nav {
+  display: flex;
+  justify-content: center;
+  gap: 24px;
+}
+
+.site-footer a {
+  display: inline-flex;
+  align-items: center;
+  min-block-size: 44px;
+}
+
+html:has(.legal-dialog[open]),
+html:has(.legal-dialog:target) {
+  overflow: hidden;
+}
+
+.legal-dialog {
+  position: fixed;
+  inset: 0;
+  inline-size: min(48rem, calc(100% - 32px));
+  max-inline-size: none;
+  max-block-size: calc(100svh - 32px);
+  margin: auto;
+  border: 1px solid color-mix(in srgb, var(--color-sand) 45%, transparent);
+  border-block-start: 4px solid var(--color-accent);
+  border-radius: 12px;
+  padding: 0;
+  overflow: hidden;
+  background: var(--color-dialog);
+  color: var(--color-cream);
+  box-shadow: 0 24px 80px var(--color-shadow);
+}
+
+.legal-dialog::backdrop {
+  background: var(--color-overlay);
+  backdrop-filter: blur(5px);
+}
+
+/* Fragment links still open the complete text if JavaScript is unavailable. */
+.legal-dialog:target:not([open]) {
+  display: block;
+  z-index: 3;
+  box-shadow: 0 0 0 100vmax var(--color-overlay);
+}
+
+.legal-shell {
+  display: flex;
+  flex-direction: column;
+  max-block-size: min(54rem, calc(100svh - 38px));
+}
+
+.legal-header {
+  display: flex;
+  flex: none;
+  align-items: center;
+  justify-content: space-between;
+  gap: 16px;
+  border-block-end: 1px solid color-mix(in srgb, var(--color-sand) 25%, transparent);
+  padding: 12px clamp(18px, 4vw, 36px);
+}
+
+.legal-header img {
+  inline-size: 48px;
+  block-size: 38px;
+}
+
+.legal-close {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  gap: 12px;
+  min-block-size: 44px;
+  border-radius: 6px;
+  padding-inline: 12px;
+  color: var(--color-sand);
+  font-size: 14px;
+}
+
+.legal-close:hover {
+  background: color-mix(in srgb, var(--color-cream) 8%, transparent);
+  text-decoration: none;
+}
+
+.legal-close span {
+  font-size: 28px;
+  line-height: 1;
+}
+
+.legal-copy {
+  min-block-size: 0;
+  padding: clamp(20px, 4vw, 36px);
+  overflow: auto;
+  overscroll-behavior: contain;
+  text-align: start;
+  overflow-wrap: anywhere;
+  font-size: 16px;
+  font-style: normal;
+  line-height: 1.65;
+  scrollbar-color: var(--color-sand) var(--color-dialog);
+}
+
+.legal-copy h1 {
+  margin: 0 0 24px;
+  color: var(--color-cream);
+  font-size: clamp(26px, 4vw, 34px);
+  font-style: italic;
+  line-height: 1.2;
+}
+
+.legal-copy h2 {
+  margin: 32px 0 16px;
+  color: var(--color-sand);
+  font-size: 22px;
+  line-height: 1.35;
+}
+
+.legal-copy h3 {
+  margin: 24px 0 12px;
+  color: var(--color-sand);
+  font-size: 18px;
+  line-height: 1.4;
+}
+
+.legal-copy h4 {
+  margin: 20px 0 10px;
+  font-size: 16px;
+  line-height: 1.5;
+}
+
+.legal-copy p,
+.legal-copy ul {
+  margin-block: 0 16px;
+}
+
+.legal-copy ul {
+  padding-inline-start: 24px;
+}
+
+.legal-copy li + li {
+  margin-block-start: 8px;
+}
+
+.legal-copy a {
+  color: var(--color-sand);
+  text-decoration: underline;
+}
+
+.legal-copy > :last-child {
+  margin-block-end: 0;
+}
+
 @media (width > 1024px) {
   body::after {
     position: fixed;