Flex bug Firefox?

by agib

HTML

<div class="panel-container">
    <div class="panel panel-left">
        Bacon ipsum dolor amet corned beef flank turkey turducken swine boudin venison tongue short loin jerky pork. Drumstick shank andouille, pork meatball sausage meatloaf tri-tip pancetta cupim turkey hamburger pastrami fatback pig. Kevin chuck turducken sausage pastrami leberkas beef ribs pig ground round flank tri-tip meatloaf tenderloin. Pork belly biltong shank jowl sirloin landjaeger, prosciutto meatloaf cow alcatra.

Sausage pastrami pork belly flank kielbasa, picanha meatloaf porchetta andouille. Sirloin short loin prosciutto alcatra shoulder bacon jerky pancetta bresaola spare ribs pork chuck capicola tongue. T-bone tri-tip swine corned beef sirloin. Tri-tip tongue rump, shank jerky drumstick tenderloin. Drumstick meatball capicola rump, short ribs flank hamburger short loin biltong picanha tri-tip frankfurter pork chop pastrami kevin.

Brisket shoulder jerky cow, ham hock capicola strip steak tongue cupim tail short ribs pork spare ribs boudin. Sirloin ham hock andouille flank chuck sausage, meatloaf bacon corned beef tongue pork belly tri-tip shoulder landjaeger. Kevin prosciutto sirloin turducken sausage bresaola pancetta bacon picanha pork belly pork loin leberkas frankfurter chicken. Shoulder sirloin alcatra landjaeger pork chop rump beef hamburger kielbasa ground round salami doner. Drumstick corned beef tri-tip prosciutto sausage kielbasa.

Ball tip pork capicola, meatloaf andouille pig turducken pastrami chuck cupim venison doner pork chop flank. Short ribs picanha alcatra tri-tip, ball tip pork belly shoulder ground round ham rump andouille tenderloin. Spare ribs hamburger short ribs chuck bresaola, sirloin shankle jowl turkey ham pancetta drumstick. Pancetta short ribs tongue shankle sausage tri-tip.

Leberkas ground round spare ribs corned beef turkey cupim, bresaola chicken shank landjaeger prosciutto. Hamburger chicken cow pork loin porchetta tri-tip sirloin ham swine pork...

CSS

html,
body {
    height: 100%;
    width: 100%;    
}
.panel-container {
    height: 100%;
    width: 100%;
    display: flex;
}
.panel {
    display: flex;
    flex: 1;
    color: #000;
    overflow-y: auto;
}
.panel-left {
    background-color: green;
}
.panel-right {
    background-color: lightblue;
}