$card-group-margin: .25rem; // Assuming Boost default preset is used.
$card-deck-margin: $card-group-margin !default;
$card-gutter : $card-deck-margin * 2;

body.zoomin {
    .dashboard-card-deck:not(.fixed-width-cards) {
        @media (min-width: 576px) {
            .dashboard-card {
                width: calc(100% - #{$card-gutter});
            }
        }
        @media (min-width: 840px) {
            .dashboard-card {
                width: calc(50% - #{$card-gutter});
            }
        }
        @media (min-width: 1100px) {
            .dashboard-card {
                width: calc(33.33% - #{$card-gutter});
            }
        }
        @media (min-width: 1360px) {
            .dashboard-card {
                width: calc(25% - #{$card-gutter});
            }
        }
    }
}

body:not(.zoomin) {
    .dashboard-card-deck:not(.fixed-width-cards) {
        @media (min-width: 576px) {
            .dashboard-card {
                width: calc(100% - #{$card-gutter});
            }
        }
        @media (min-width: 768px) {
            .dashboard-card {
                width: calc(50% - #{$card-gutter});
            }
        }
        @media (min-width: 1100px) {
            .dashboard-card {
                width: calc(33.33% - #{$card-gutter});
            }
        }
        @media (min-width: 1360px) {
            .dashboard-card {
                width: calc(25% - #{$card-gutter});
            }
        }
    }
}

body:not(.zoomin) #page.fullin {
    .dashboard-card-deck:not(.fixed-width-cards) {
        @media (min-width: 576px) {
            .dashboard-card {
                width: calc(100% - #{$card-gutter});
            }
        }
        @media (min-width: 768px) {
            .dashboard-card {
                width: calc(50% - #{$card-gutter});
            }
        }
        @media (min-width: 1100px) {
            .dashboard-card {
                width: calc(33.33% - #{$card-gutter});
            }
        }
        @media (min-width: 1360px) {
            .dashboard-card {
                width: calc(25% - #{$card-gutter});
            }
        }
    }
}

body.zoomin #page.fullin {
    .dashboard-card-deck:not(.fixed-width-cards) {
        @media (min-width: 576px) {
            .dashboard-card {
                width: calc(50% - #{$card-gutter});
            }
        }
        @media (min-width: 840px) {
            .dashboard-card {
                width: calc(33.33% - #{$card-gutter});
            }
        }
        @media (min-width: 1100px) {
            .dashboard-card {
                width: calc(25% - #{$card-gutter});
            }
        }
        @media (min-width: 1360px) {
            .dashboard-card {
                width: calc(20% - #{$card-gutter});
            }
        }
    }
}