Cachet/resources/assets/sass/_errors.scss

body.error-page {
    background-color: #f3f3f4;

    .middle-box {
        height: 400px;
        width: 400px;
        position: absolute;
        top: 50%;
        left: 50%;
        margin-top: -250px;
        margin-left: -200px;
        z-index: 100;

        h1 {
            font-size: 9em;
        }
    }

    h3 {
        &.font-bold {
            font-weight: 600;
        }
    }
}