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<meta charset="utf-8">
<title>Test behavior of 'min-height:auto' and 'min-width:auto' (Bug 763689 and Bug 1304636)</title>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
<a target="_blank" href="">Mozilla Bug 763689</a>
<div id="display">
<div id="block-item">abc</div>
<div style="display: flex">
<div id="horizontal-flex-item">abc</div>
<div id="horizontal-flex-item-OH" style="overflow: hidden">def</div>
<div style="display: flex; flex-direction: column">
<div id="vertical-flex-item">abc</div>
<div id="vertical-flex-item-OH" style="overflow: hidden">def</div>
<div style="display: grid">
<div id="grid-item"></div>
<div id="grid-item-OH" style="overflow: hidden"></div>
<pre id="test">
<script type="application/javascript">
"use strict";
* Test 'min-height:auto' and 'min-width:auto' (Bug 763689 and Bug 1304636)
* ========================================================
* This test checks the computed-style value of the "auto" keyword introduced
* for the "min-height" and "min-width" properties in CSS3 Flexbox Section 4.5
* and CSS3 Grid Section 6.2.
* Quoting that chunk of spec:
* # auto
* # On a flex item whose overflow is visible in the main axis,
* # when specified on the flex item’s main-axis min-size property,
* # specifies an automatic minimum size. It otherwise computes to 0
* # (unless otherwise defined by a future specification).
// Given an element ID, this function sets the corresponding
// element's inline-style min-width and min-height explicitly to "auto".
function setElemMinSizesToAuto(aElemId) {
var elem = document.getElementById(aElemId);
is(, "", "min-width should be initially unset"); = "auto";
is(, "auto", "min-width should accept 'auto' value");
is(, "", "min-height should be initially unset"); = "auto";
is(, "auto", "min-height should accept 'auto' value");
// Given an element ID, this function compares the corresponding element's
// computed min-width and min-height against expected values.
function checkElemMinSizes(aElemId,
var elem = document.getElementById(aElemId);
is(window.getComputedStyle(elem).minWidth, aExpectedMinWidth,
"checking min-width of " + aElemId);
is(window.getComputedStyle(elem).minHeight, aExpectedMinHeight,
"checking min-height of " + aElemId);
// This function goes through all the elements we're interested in
// and checks their computed min-sizes against expected values,
// farming out each per-element job to checkElemMinSizes.
function checkAllTheMinSizes() {
// This is the normal part -- generally, the default value of "min-width"
// and "min-height" (auto) computes to "0px".
checkElemMinSizes("block-item", "0px", "0px");
// ...but for a flex item or grid item, "min-width: auto" and
// "min-height: auto" both compute to "auto" (even in cases where
// we know it'll actually resolve to 0 in layout, like for example
// when the item has "overflow:hidden").
checkElemMinSizes("horizontal-flex-item", "auto", "auto");
checkElemMinSizes("horizontal-flex-item-OH", "auto", "auto");
checkElemMinSizes("vertical-flex-item", "auto", "auto");
checkElemMinSizes("vertical-flex-item-OH", "auto", "auto");
checkElemMinSizes("grid-item", "auto", "auto");
checkElemMinSizes("grid-item-OH", "auto", "auto");
// Main test function
function main() {
// First: check that min-sizes are what we expect, with min-size properties
// at their initial value.
// Now, we *explicitly* set min-size properties to "auto"...
var elemIds = [ "block-item",
// ...and try again (should have the same result):