Responsive Website Tester

.tester {
background-color: #fff;
padding: 20px;
border-radius: 8px;
box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
max-width: 600px;
width: 100%;
}

h2 {
text-align: center;
color: #333;
}

.input-group {
margin-bottom: 20px;
}

.input-group input {
width: calc(100% - 40px);
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
outline: none;
}

.input-group button {
width: 40px;
padding: 10px;
border: none;
background-color: #007bff;
color: #fff;
border-radius: 4px;
cursor: pointer;
font-size: 16px;
outline: none;
}

.output {
background-color: #f0f0f0;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
overflow: auto;
}