CustomizationsModal.vue - add a way for users to customize css of their invoices and store it per team,

fix print styles for invoices,
add keys to translations with default English values

src/components/invoices/CustomizationsModal.vue

@@ -0,0 +1,85 @@
+<template>
+    <BModal v-model="isOpen"
+            centered
+            hide-footer
+            :title="$t('title')"
+            size="lg"
+            scrollable
+            content-class="bg-base dp--24 text-center">
+        <AppTextarea :value="team.custom_css"
+                     @change="updateProp({ custom_css: $event })"
+                     :label="$t('textarea_label')"
+                     field="custom_css"
+                     :errors="errors"
+                     input-classes="min-vh-50 text-monospace"
+                     class="text-left"/>
+    </BModal>
+</template>
+
+<script>
+import { BModal } from 'bootstrap-vue';
+import AppTextarea from '@/components/form/AppTextarea';
+import Errors from '@/utils/errors';
+import NotificationService from '@/services/notification.service';
+import { mapGetters } from 'vuex';
+
+export default {
+  i18nOptions: {
+    namespaces: 'customizations-modal',
+  },
+  data() {
+    return {
+      errors: new Errors(),
+    };
+  },
+  components: {
+    BModal,
+    AppTextarea,
+  },
+  computed: {
+    isOpen: {
+      get() {
+        return this.$store.state.invoices.isCustomizationsModalOpen;
+      },
+      set(val) {
+        this.$store.commit('invoices/isCustomizationsModalOpen', val);
+      },
+    },
+    ...mapGetters({
+      team: 'teams/team',
+    }),
+  },
+  watch: {
+    team() {
+      this.updateStyleEl(this.team.custom_css);
+    }
+  },
+  created() {
+    this.initStyleEl();
+  },
+  methods: {
+    initStyleEl() {
+      const styleEl = document.createElement('style');
+      styleEl.setAttribute('id', 'custom-styles');
+      styleEl.setAttribute('type', 'text/css');
+      document.head.appendChild(styleEl);
+    },
+    updateStyleEl(styles) {
+      const styleEl = document.getElementById('custom-styles');
+      styleEl.innerHTML = styles;
+    },
+    close() {
+      this.isOpen = false;
+    },
+    updateProp(props) {
+      this.errors.clear();
+      this.$store.dispatch('teams/updateTeam', props)
+        .then(() => {
+          NotificationService.success(this.$t('updated'));
+          this.updateStyleEl(props.custom_css);
+        })
+        .catch(err => this.errors.set(err.errors));
+    },
+  },
+};
+</script>