Using flexbox to set up a collapsible field that can grow with available space.

gistfile1.txt

<style>
* {
    padding: 0;
	margin:0;
	line-height: 1em;
	font-size: 16px;
}
.parent {
	max-width: 100%;
	background: #eee;
/* 	display: table; */
/* 	display: -webkit-flex; */
/* 	-webkit-flex-flow: column; */
}
.flex-container > div {
/*       -webkit-flex: 1 1 auto; */

}
.addr {
	text-overflow: ellipsis;
	overflow: hidden;
	
	min-width: 0px;
	max-height: 1em;
	background: #aabbcc;
/* 	max-width: auto; */
	white-space: nowrap;
}
.unit {
/*
	text-overflow: ellipsis;
	overflow: hidden;
*/
	white-space: nowrap;
	background: #ccbbaa;
}
.flex-container {
    display: -ms-flexbox;
    display: -webkit-flex;
    display: flex;
    -webkit-flex-direction: row;
    -ms-flex-direction: row;
    flex-direction: row;
    -webkit-flex-wrap: nowrap;
    -ms-flex-wrap: nowrap;
    flex-wrap: nowrap;
    -webkit-justify-content: flex-start;
    -ms-flex-pack: start;
    justify-content: flex-start;
    -webkit-align-content: stretch;
    -ms-flex-line-pack: stretch;
    align-content: stretch;
    -webkit-align-items: stretch;
    -ms-flex-align: stretch;
    align-items: stretch;
    }

.flex-item:nth-child(1) {
    -webkit-order: 0;
    -ms-flex-order: 0;
    order: 0;
    -webkit-flex: 0 1 auto;
    -ms-flex: 0 1 auto;
    flex: 0 1 auto;
    -webkit-align-self: auto;
    -ms-flex-item-align: auto;
    align-self: auto;
    }

.flex-item:nth-child(2) {
    -webkit-order: 0;
    -ms-flex-order: 0;
    order: 0;
    -webkit-flex: 1 1 auto;
    -ms-flex: 1 1 auto;
    flex: 1 1 auto;
    -webkit-align-self: auto;
    -ms-flex-item-align: auto;
    align-self: auto;
    }
</style>

<div class="flex-container flex-container-style fixed-height">
	<div class="flex-item addr">123 main long street name here blah&nbsp;</div>
	<div class="flex-item unit">apartment #2</div>
</div>