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<div class="container">
    <h3>Dialog Window</h3>
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi vulputate vitae nibh sed sodales. Maecenas non vulputate lacus, sed convallis eros. Cras sollicitudin, felis sit amet pharetra mattis, metus lectus ullamcorper magna.</p>
    <button>Confirm</button>
</div>

:root{
    --primary-color: #B1D7DC;
    --accent-color: #FF3F90;
}

html{
    background-color: var(--primary-color);
}

h3{
    border-bottom: 2px solid var(--primary-color);
}

button{
    color: var(--accent-color);
    border: 1px solid var(--accent-color);
}

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html{
    padding: 30px;
    font: normal 13px/1.5 sans-serif;
    color: #546567;
    background-color: var(--primary-color);
}

.container{
    background: #fff;
    padding: 20px;
}

h3{
    padding-bottom: 10px;
    margin-bottom: 15px;
}

p{
    background-color: #fff;
    margin: 15px 0;
}

button{
    font-size: 13px;
    padding: 8px 12px;
    background-color: #fff;
    border-radius: 3px;
    box-shadow: none;
    text-transform: uppercase;
    font-weight: bold;
    cursor: pointer;
    opacity: 0.8;
    outline: 0;
}

button:hover{
    opacity: 1;
}