CSS padding-block-start Property - Playground Example

<!DOCTYPE html><html><head><style type="text/css">/* Basic page styling */
:root {
    --card-bg: #f3faf4;
    --accent: #2b8a3e;
}

body {
    font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial;
    display: flex;
    justify-content: center;
    padding: 40px;
    background: #eef6f2;
}

.container {
    max-width: 760px;
    width: 100%;
}

h1 {
    margin: 0 0 18px 0;
    font-size: 20px;
}

.card {
    background: var(--card-bg);
    border: 2px dashed var(--accent);
    border-radius: 8px;
    width: 100%;
    padding-inline: 16px;       /* horizontal padding */
    padding-block-start: 28px; /* logical start of the block axis */
    padding-block-end: 16px;   /* logical end of the block axis */
    box-sizing: border-box;
    margin-bottom: 18px;
}

.label {
    margin: 0 0 8px 0;
    font-weight: 600;
    color: var(--accent);
}

.content {
    margin: 0;
    color: #1f3d2f;
}

/* Vertical writing mode example: block axis rotates  -  padding-block-start applies to the new block-start edge */
.card.vertical-rl {
    writing-mode: vertical-rl;
    width: 220px;
    height: 220px;
}</style></head><body><div class="container">
    <h1>padding-block-start demo</h1>

    <div class="card">
        <p class="label">This box uses <code>padding-block-start</code>:</p>
        <p class="content">The top logical padding is applied to the start of the block axis.</p>
    </div>

    <div class="card vertical-rl">
        <p class="label">Same with <code>writing-mode: vertical-rl</code>:</p>
        <p class="content">In vertical writing mode the block axis changes, so <code>padding-block-start</code> moves accordingly.</p>
    </div>
</div></body></html>