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HTML

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Insecure Resource

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CSS

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CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

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CSS Base

About CSS Base

It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.

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About Vendor Prefixing

To get the best cross-browser support, it is a common practice to apply vendor prefixes to CSS properties and values that require them to work. For instance -webkit- or -moz-.

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JavaScript

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JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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Babel includes JSX processing.

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HTML 

              
                <!--  Orig radiento: https://codepen.io/argyleink/pen/BaGrXmv -->
<fieldset id="radiento" class="bento">
  <div>
    <input type="radio" id="huey" name="drone" value="huey" checked>
    <label for="huey">Huey</label>
  </div>

  <div>
    <input type="radio" id="dewey" name="drone" value="dewey">
    <label for="dewey">Dewey</label>
  </div>

  <div>
    <input type="radio" id="louie" name="drone" value="louie">
    <label for="louie">Louie</label>
  </div>
</fieldset>
!

CSS 

              
                @import "https://unpkg.com/open-props" layer(design.system);
@import "https://unpkg.com/open-props/normalize.min.css" layer(demo.support);

@property --vt-checked {
  syntax: "<custom-ident>";
  inherits: false;
  initial-value: OFF;
}
#radiento input:checked {
  --vt-checked: ON;
}

div:has(#huey) {
  background: lime;
}

div:has(#dewey) {
  background: hotpink;
}

::view-transition-group(*) {
  animation-timing-function: var(--ease-squish-1);
  animation-timing-function: var(--ease-spring-2);
  animation-duration: .75s;
}

/* fixex ghosting at the bottom */
::view-transition-old(opt-1),
::view-transition-old(opt-2),
::view-transition-old(opt-3),
::view-transition-new(opt-1),
::view-transition-new(opt-2),
::view-transition-new(opt-3) {
  height: 100%;
}

@layer demo {
  .bento {
    display: grid;
    grid-template-columns: 2fr 1fr;
    grid-template-rows: 1fr 1fr;
    gap: var(--size-3);
    
    min-inline-size: 75vw;
    aspect-ratio: var(--ratio-widescreen);
    
    & > * {
      border-radius: var(--radius-3);
      background: var(--surface-2);
      
      @media (prefers-reduced-motion: no-preference) {
        &:nth-child(1) {
          view-transition-name: opt-1;
          & > label {
            view-transition-name: opt-1-label;
          }
          & > input {
            view-transition-name: opt-1-input;
          }
        }
        &:nth-child(2) {
          view-transition-name: opt-2;
          & > label {
            view-transition-name: opt-2-label;
          }
          & > input {
            view-transition-name: opt-2-input;
          }
        }
        &:nth-child(3) {
          view-transition-name: opt-3;
          & > label {
            view-transition-name: opt-3-label;
          }
          & > input {
            view-transition-name: opt-3-input;
          }
        }

        & :is(label, input) {
          width: fit-content;
        }
      }
    }
    
    & > div:has(input:checked) {
      grid-row: 1 / -1;
      grid-column: 1;
    }
  }
}

@layer demo.support {
  html {
    view-transition-name: none;
  }
  
  body {
    display: grid;
    place-content: center;
    padding: var(--size-5);
    gap: var(--size-5);
  } 
  
  fieldset {
    border: none;
    
    > div {
      display: grid;
      grid: 1fr / 1fr;
      padding: var(--size-3);

      & > label {
        grid-area: 1 / 1;
      }
    }
  }
}
!

JS 

              
                import CSSStyleObserver, { NotificationMode, ReturnFormat } from "https://esm.sh/@bramus/style-observer";

// Utility fn to clear an array
const clearArray = (array) => {
  while (array.length > 0) {
    array.pop();
  }
}

// Function than handles a pair of changes
const handleChanges = async (changes) => {
  // We need a pair
  if (changes.length != 2) return;
  
  // Extract changes
  const [change1, change2] = changes;
  
  // Revert back to old state
  change1.element.checked = change1.previousValue == 'ON';
  change2.element.checked = change2.previousValue == 'ON';
  
  // Now reapply new state, with a View Transition.
  try {
    const t = document.startViewTransition(() => {
      change1.element.checked = change1.value == 'ON';
      change2.element.checked = change2.value == 'ON';
    });

    // Get ready for next pair
    await t.finished;
  } finally {
    clearArray(changes);
  }
}

const pairOfChanges = [];
const styleObserver = new CSSStyleObserver(
  ['--vt-checked'],
  (changes) => {
    const change = changes['--vt-checked'];
    
    // Ignore initial triggers from CSSStyleObserver
		if (!change || !change.previousValue) return;
    
    // Ignore when a pair is currently being handled
    if (pairOfChanges.length == 2) return;
    
    // Store the change, and see if we can handle it
    pairOfChanges.push(change);
    handleChanges(pairOfChanges);
	},
  {
      notificationMode: NotificationMode.CHANGED_ONLY,
      returnFormat: ReturnFormat.OBJECT,
   }
);

document.querySelectorAll('#radiento input').forEach($radio => {
  styleObserver.attach($radio);
});
!
999px

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