diff --git a/src/components/app-base.js b/src/components/app-base.js
index 00ac09b..42cc92d 100644
--- a/src/components/app-base.js
+++ b/src/components/app-base.js
@@ -6,6 +6,9 @@ class AppBase extends HTMLElement {
     super();
     this.attachShadow({ mode: 'open' });
     this.text = text;
+    this.properties = {
+      color: '#324BFF',
+    };
     this.store = new Store();
   }
   
@@ -14,27 +17,101 @@ class AppBase extends HTMLElement {
     this.render();
   }
 
-  renderText() {
+  renderOptions() {
     const textList = this.store.getRecords();
     return textList.map((item) => `<option value=${item.id}>${item.text}</option>`).join('\n');
   }
 
-  render(action = 'INITIAL') {
-    if (![Store.actions.ADD_LINE, Store.actions.REMOVE_LINE, Store.actions.UNDO, 'INITIAL'].includes(action)) {
+  render(action = 'INIT') {
+    if (![Store.actions.ADD_LINE, Store.actions.REMOVE_LINE, Store.actions.UNDO, 'INIT'].includes(action)) {
       return; // Only render if content changed
     }
 
     this.shadowRoot.innerHTML = `
-    <main-window title="${this.text.title}" description="${this.text.description}">
-      <select multiple is="item-list">
-        ${this.renderText()}
+    <style>
+      * {
+        margin: 0;
+      }
+      #window {
+        width: 800px;
+        height: 477px;
+        background: #FFFFFF 0% 0% no-repeat padding-box;
+        box-shadow: 0px 5px 12px #0000001F;
+        border-radius: 20px;
+        opacity: 1;
+        padding: 50px;
+        display: flex;
+        flex-direction: column;
+        row-gap: 35px;
+      }
+      #title {
+        height: 49px;;
+        margin-bottom: -12px;
+        text-align: center;
+        font-size: 40px;
+        font-family: "Montserrat", sans-serif;
+        font-weight: normal;
+        letter-spacing: 0px;
+        color: #333333;
+        opacity: 1;
+      }
+      #description {
+        text-align: center;
+        height: 74px;
+        text-align: center;
+        font-size: 18px;
+        font-family: "Montserrat", sans-serif;
+        font-weight: normal;
+        letter-spacing: 0px;
+        color: #333333;
+        opacity: 1;
+      }
+      #list {
+        padding: 13px;
+      }
+      #list > option {
+        height: 40px;
+        align-content: center;
+        padding-left: 15px;
+        font-size: 18px;
+        font-family: "Montserrat", sans-serif;
+        font-weight: normal;
+      }
+      #list > option:checked {
+        background: ${this.properties.color} linear-gradient(0deg, ${this.properties.color} 0%, ${this.properties.color} 100%);
+        box-shadow: 0 0 10px 100px ${this.properties.color} inset;
+        color: #fff;
+        outline: none;
+      }
+      #button-bar {
+        display: flex;
+        column-gap: 35px
+      }
+      #button-bar > custom-button:last-child {
+        margin-left: auto;
+      }
+      #undo-char {
+        margin-top: 3px;
+      }
+    </style>
+    <div id="window">
+      <h1 id="title">${this.text.title}</h1>
+      <p id="description">${this.text.description}</p>
+      <select id="list" multiple is="item-list">
+        ${this.renderOptions()}
       </select>
       <span id="button-bar">
-        <custom-button action="${Store.actions.REMOVE_LINE}" color="#324bff">Delete</custom-button>
-        <custom-button action="${Store.actions.ADD_LINE}" color="#324bff">Add</custom-button>
-        <custom-button action="${Store.actions.UNDO}" outline color="#324bff">Undo</custom-button>
+        <custom-button action="${Store.actions.UNDO}" outline width="81px" color="${this.properties.color}">
+          <svg xmlns="http://www.w3.org/2000/svg" xml:space="preserve" id="undo-char" width="21" height="19" viewBox="0 0 5.556 5.027">
+            <path d="M.681 2.22a2.38 2.38 0 0 1 4.742.294v0a2.38 2.38 0 0 1-4.526 1.03" style="fill:none;stroke:${this.properties.color};stroke-width:.264583;stroke-linecap:round;stroke-dasharray:none"/>
+            <path d="m.132 1.525.437.964.964-.437" style="fill:none;stroke:${this.properties.color};stroke-width:.264583;stroke-linecap:round;stroke-linejoin:round;stroke-dasharray:none;stroke-opacity:1"/>
+          </svg>
+
+        </custom-button>
+        <custom-button action="${Store.actions.REMOVE_LINE}" outline width="124px" color="${this.properties.color}">Delete</custom-button>
+        <custom-button action="${Store.actions.ADD_LINE}" width="138px" color="${this.properties.color}">Add</custom-button>
       </span>
-    </main-window>
+    </div>
     `;
   }
 }
diff --git a/src/components/custom-button.js b/src/components/custom-button.js
index 290e095..7c9c637 100644
--- a/src/components/custom-button.js
+++ b/src/components/custom-button.js
@@ -1,7 +1,7 @@
 import Store from '../modules/store.js';
 
 class CustomButton extends HTMLElement {
-  static observedAttributes = ['outline', 'color', 'action'];
+  static observedAttributes = ['outline', 'color', 'width', 'action'];
 
   constructor() {
     super();
@@ -36,7 +36,7 @@ class CustomButton extends HTMLElement {
         border-style: ${isOutline ? 'solid' : 'hidden'};
         border-color: ${this.getAttribute('color')};
         opacity: 1;
-        width: 138px;
+        width: ${this.getAttribute('width')};
         height: 49px;
         background-color: ${isOutline ? 'white' : this.getAttribute('color')};
         color: ${isOutline ? this.getAttribute('color') : 'white'};
diff --git a/src/components/item-list.js b/src/components/item-list.js
index 54caa20..f2bc4f6 100644
--- a/src/components/item-list.js
+++ b/src/components/item-list.js
@@ -21,7 +21,7 @@ class ItemList extends HTMLSelectElement {
   }
 
   updateStyle() {
-      this.style.width = '800px';
+      this.style.width = '100%';
       this.style.height = '227px';
       this.style.background = '#F7F7F7 0% 0% no-repeat padding-box';
       this.style.border = '1px solid #CCCCCC';
diff --git a/src/components/main-window.js b/src/components/main-window.js
index f0af685..c579b2b 100644
--- a/src/components/main-window.js
+++ b/src/components/main-window.js
@@ -15,27 +15,23 @@ class MainWindow extends HTMLElement {
   }
 
   render() {
-    const title = this.getAttribute('title') || "No title";
-    const description = this.getAttribute('description') || "No description";
 
     this.shadowRoot.innerHTML = `
     <style>
       #window {
-        width: 900px;
-        height: 577px;
+        width: 800px;
+        height: 477px;
         background: #FFFFFF 0% 0% no-repeat padding-box;
         box-shadow: 0px 5px 12px #0000001F;
         border-radius: 20px;
         opacity: 1;
-      }
-      #content {
-        width: 800px;
-        margin: 0 50px 13px 50px;
+        padding: 50px;
+        display: flex
       }
       h1 {
-        top: 221px;
-        margin: 50px 50px 13px 50px;
         height: 49px;
+        margin: 0;
+        margin-bottom: 13px;
         text-align: center;
         font-size: 40px;
         font-family: "Montserrat", sans-serif;
@@ -45,12 +41,10 @@ class MainWindow extends HTMLElement {
         opacity: 1;
       }
       p {
-        margin: 0 50px 0 50px;
         text-align: center;
         height: 74px;
-
-        /* UI Properties */
-
+        margin: 0;
+        margin-bottom: 35px;
         text-align: center;
         font-size: 18px;
         font-family: "Montserrat", sans-serif;
@@ -63,9 +57,7 @@ class MainWindow extends HTMLElement {
     <div id="window">
       <h1>${title}</h1>
       <p>${description}</p>
-      <div id="content" >
-        <slot></slot>
-      <div/>
+      <slot></slot>
     </div>
     `;
   }
diff --git a/src/components/undo-arrow.js b/src/components/undo-arrow.js
new file mode 100644
index 0000000..e69de29
diff --git a/src/main.js b/src/main.js
index a0e292f..9dfe32e 100644
--- a/src/main.js
+++ b/src/main.js
@@ -1,5 +1,4 @@
 import './components/app-base.js';
-import './components/main-window.js';
 import './components/custom-button.js';
 import './components/item-list.js';
 
diff --git a/src/modules/store.js b/src/modules/store.js
index 8342db3..0c5e31b 100644
--- a/src/modules/store.js
+++ b/src/modules/store.js
@@ -48,14 +48,13 @@ export default class Store {
         };
         break;
       case this.constructor.actions.REMOVE_LINE:
-        const linesToRemove = this.state.selected.map((id, index) => ({
-          id: this.state.records.length + index,
-          targetId: id,
-          action: 'remove',
-        }));
         this.state = {
           ...this.state,
-          records: [ ...this.state.records, ...linesToRemove],
+          records: [ ...this.state.records, {
+            id: this.state.records.length,
+            targetIds: this.state.selected,
+            action: 'remove',
+          }],
           selected: [],
         };
         break;
@@ -85,7 +84,11 @@ export default class Store {
         return acc.concat({id: current.id, text: current.text});
       }
       if (current.action === "remove") {
-        return acc.filter((item) => item.id !== current.targetId);
+        let temp = acc;
+        for (const id of current.targetIds) {
+          temp = temp.filter((item) => item.id !== id);
+        }
+        return temp;
       }
       console.error(`Action ${current.action} not valid`);
     }, []);