Responsiveness to Mobile in CSS

Im trying to make my bottom sheet responsive to mobile and desktop. you can see in laptop the bottom sheet when you click new topic it works all fine:

But then lets see it in a mobile version(On a regular Iphone 5):

You can see its beyond terrible... My HTML For that view is(Minimized):

<div class="toolbar_new_topic" ng-if="authDataDesc!=null">
  <md-button id="NEW_TOPIC_BUTTON" ng-click="showNewTopic($event)">
    <ng-md-icon icon="add_box" style="fill: white" size="20" id="add_icon"></ng-md-icon>
    <span id="text_new_topic" color="white">Create a New Topic</span>
  </md-button>
</div>

And my CSS Is:

.listdemoListControls md-divider {
    margin-top: 0;
    margin-bottom: 0
}

.listdemoListControls md-list {
    padding-top: 0
}

.listdemoListControls md-list-item ._md-list-item-inner>._md-list-item-inner>p,
.listdemoListControls md-list-item ._md-list-item-inner>p,
.listdemoListControls md-list-item>._md-list-item-inner>p,
.listdemoListControls md-list-item>p {
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none
}

body,
html {
    background: #DDD
}

#MD-ICON-1 {
    position: relative;
    left: -40px;
    bottom: -23px
}

.avatar_custom {
    width: 20px;
    height: 20px
}

.avatar_creator {
    border-radius: 50%;
    position: relative;
    height: 30px;
    top: 10px;
    width: 30px
}

.toolbar_new_topic {
    display: flex;
    flex-direction: row;
    justify-content: flex-end
}

#NEW_TOPIC_BUTTON {
    background-color: #81C784;
    font-weight: 700;
    margin-right: 50px
}

span.views_icon {
    position: relative;
    top: 5px
}

span.replies_list.md-secondary.ng-binding {
    position: relative;
    left: -55px;
    top: 18px
}

.user-avatar-wrapper {
    padding: 0;
    margin: 0;
    height: 50px;
    width: 50px;
    border-radius: 50%;
    min-width: 50px;
    display: flex;
    align-items: center
}

.tags a,
.tags li {
    height: 24px;
    line-height: 24px;
    font-size: 11px
}

.search_autocomplete,
input#input-0 {
    font-family: FontAwesome;
    font-style: normal;
    font-weight: 400;
    text-decoration: inherit
}

.tags {
    margin: 0;
    padding: 0;
    position: absolute;
    right: 24px;
    bottom: -12px;
    list-style: none
}

.tags li {
    float: left;
    position: relative
}

.tags a:after,
.tags a:before {
    content: "";
    position: absolute;
    float: left
}

.tags a {
    float: left;
    margin-left: 20px;
    padding: 0 10px 0 12px;
    background: #0089e0;
    color: #fff;
    text-decoration: none;
    -moz-border-radius-bottomright: 4px;
    -webkit-border-bottom-right-radius: 4px;
    border-bottom-right-radius: 4px;
    -moz-border-radius-topright: 4px;
    -webkit-border-top-right-radius: 4px;
    border-top-right-radius: 4px
}

.tags a:before {
    top: 0;
    left: -12px;
    width: 0;
    height: 0;
    border-color: transparent #0089e0 transparent transparent;
    border-style: solid;
    border-width: 12px 12px 12px 0
}

.tags a:after {
    top: 10px;
    left: 0;
    width: 4px;
    height: 4px;
    -moz-border-radius: 2px;
    -webkit-border-radius: 2px;
    border-radius: 2px;
    background: #fff;
    -moz-box-shadow: -1px -1px 2px #004977;
    -webkit-box-shadow: -1px -1px 2px #004977;
    box-shadow: -1px -1px 2px #004977
}

.tags a:hover {
    background: #555
}

.tags a:hover:before {
    border-color: transparent #555 transparent transparent
}

span.last_activity.ng-binding {
    position: relative;
    right: 129px
}

ul.tags {
    position: absolute;
    right: 1138px;
    bottom: 20px
}

span.bookmark_icon {
    position: relative;
    right: 130px;
    top: 1px
}

.user-avatar {
    height: 50px;
    width: 50px;
    border-radius: 50%
}

md-list.ng-scope.md-whiteframe-24dp.flex-sm-55.flex-gt-sm-45.flex-gt-md-45 {
    position: relative;
    top: 25px;
    left: 25px;
    background: #EF5350
}

md-list-item.md-3-line.ng-scope.md-clickable {
    background-color: #EF5350
}

.tags a {
    position: relative;
    left: 800px
}

Im currently Programming this website here so if you go there we can fix this problem real quick: https://ide.c9.io/amanuel2/ng-fourm

Thanks for your time!