element-web/res/css/views/elements/_RoomAliasField.pcss

/*
Copyright 2019 The Matrix.org Foundation C.I.C.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

.mx_RoomAliasField {
    /* if parent is a flex container, this allows the */
    /* width to be as wide as needed, and not 100% */
    flex: 0 1 auto;
    display: flex;
    align-items: stretch;
    min-width: 0;
    max-width: 100%;

    input {
        width: 150px;
        padding-left: 0;
        padding-right: 0;
    }

    input::placeholder {
        color: $info-plinth-fg-color;
        font-weight: normal;
    }

    .mx_Field_prefix, .mx_Field_postfix {
        color: $info-plinth-fg-color;
        border-left: none;
        border-right: none;
        font-weight: 600;
        padding: 9px 10px;
        flex: 0 0 auto;
    }

    .mx_Field_postfix {
        text-overflow: ellipsis;
        white-space: nowrap;
        overflow: hidden;
        /* this allows the domain name to show */
        /* as long as it doesn't make the input shrink */
        /* if it's too big, it shows an ellipsis */
        /* 180: 28 for prefix, 152 for input */
        max-width: calc(100% - 180px);
    }
}