files/en-us/web/css/reference/properties/inset-block-start/index.md
The inset-block-start CSS property defines the logical block start offset of an element, which maps to a physical inset depending on the element's writing mode, directionality, and text orientation. It corresponds to the {{cssxref("top")}}, {{cssxref("right")}}, {{cssxref("bottom")}}, or {{cssxref("left")}} property depending on the values defined for {{cssxref("writing-mode")}}, {{cssxref("direction")}}, and {{cssxref("text-orientation")}}.
This {{glossary("inset properties", "inset property")}} has no effect on non-positioned elements.
{{InteractiveExample("CSS Demo: inset-block-start")}}
writing-mode: horizontal-tb;
writing-mode: vertical-rl;
writing-mode: horizontal-tb;
direction: rtl;
writing-mode: vertical-lr;
<section id="default-example">
<div class="example-container" id="example-element">
<div id="abspos">
I am absolutely positioned with inset-block-start: 50px
</div>
<p>
As much mud in the streets as if the waters had but newly retired from the
face of the earth, and it would not be wonderful to meet a Megalosaurus,
forty feet long or so, waddling like an elephantine lizard up Holborn
Hill.
</p>
</div>
</section>
#example-element {
border: 0.75em solid;
padding: 0.75em;
position: relative;
width: 100%;
min-height: 200px;
unicode-bidi: bidi-override;
}
#abspos {
background-color: yellow;
color: black;
border: 3px solid red;
position: absolute;
inset-block-start: 50px;
inline-size: 140px;
}
/* <length> values */
inset-block-start: 3px;
inset-block-start: 2.4em;
inset-block-start: anchor(end);
inset-block-start: calc(anchor-size(--my-anchor height, 70px) * 2);
/* <percentage>s of the width or height of the containing block */
inset-block-start: 10%;
/* Keyword value */
inset-block-start: auto;
/* Global values */
inset-block-start: inherit;
inset-block-start: initial;
inset-block-start: revert;
inset-block-start: revert-layer;
inset-block-start: unset;
The inset-block-start property takes the same values as the {{cssxref("top")}} property.
{{cssinfo}}
{{csssyntax}}
<div>
<p class="exampleText">Example text</p>
</div>
div {
background-color: yellow;
width: 120px;
height: 120px;
}
.exampleText {
writing-mode: vertical-lr;
position: relative;
inset-block-start: 20px;
background-color: #c8c800;
}
{{EmbedLiveSample("Setting_block_start_offset", 140, 140)}}
{{Specifications}}
{{Compat}}