:root {
    --ffc-ink: #172033;
    --ffc-muted: #64748b;
    --ffc-accent: #0d6efd;
    --ffc-soft: #eef4ff;
    --ffc-panel-bg: #fff;
    --ffc-border: rgba(15, 23, 42, .12);
    --ffc-soft-border: rgba(15, 23, 42, .08);
    --ffc-shadow: rgba(15, 23, 42, .05);
}

[data-bs-theme="dark"] {
    --bs-body-bg: #2d3339;
    --bs-body-bg-rgb: 45, 51, 57;
    --bs-tertiary-bg: #262c32;
    --bs-tertiary-bg-rgb: 38, 44, 50;
    --bs-secondary-bg: #343b43;
    --bs-secondary-bg-rgb: 52, 59, 67;
    --bs-border-color: #4a535d;
    --bs-body-color: #f0f4f8;
    --bs-secondary-color: #b8c4cf;
    --ffc-ink: #e5edf8;
    --ffc-muted: #aab7c7;
    --ffc-accent: #6ea8fe;
    --ffc-soft: #3a4656;
    --ffc-panel-bg: #353c43;
    --ffc-border: rgba(226, 232, 240, .24);
    --ffc-soft-border: rgba(226, 232, 240, .16);
    --ffc-shadow: rgba(0, 0, 0, .20);
}

[data-bs-theme="dark"] .bg-white,
[data-bs-theme="dark"] .bg-light,
[data-bs-theme="dark"] .text-bg-light {
    background-color: var(--ffc-panel-bg) !important;
    color: var(--bs-body-color) !important;
}

body {
    color: var(--ffc-ink);
    -webkit-text-size-adjust: 100%;
}

input,
select,
textarea,
button {
    font-size: 16px;
}

.navbar-brand {
    letter-spacing: 0;
}

.card,
.modal-content,
.form-control,
.form-select,
.btn,
.nav-tabs .nav-link,
.toast {
    border-radius: .5rem;
}

.btn,
.form-control,
.form-select {
    min-height: 44px;
}

#adminTabs {
    flex-wrap: nowrap;
    overflow-x: auto;
    overflow-y: hidden;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: thin;
}

#adminTabs .nav-item {
    flex: 0 0 auto;
}

#adminTabs .nav-link {
    white-space: nowrap;
}

.metric {
    background: var(--ffc-panel-bg);
    border: 1px solid var(--ffc-soft-border);
    border-radius: .5rem;
    box-shadow: 0 .25rem 1rem var(--ffc-shadow);
    padding: 1rem;
    min-height: 86px;
}

.metric span {
    color: var(--ffc-muted);
    display: block;
    font-size: .875rem;
}

.metric strong {
    display: block;
    font-size: clamp(1.25rem, 4vw, 2rem);
    line-height: 1.2;
}

.flashcard-shell {
    max-width: 920px;
}

.help-page {
    max-width: 980px;
}

.direction-toggle {
    align-items: center;
    background: var(--ffc-panel-bg);
    border: 1px solid var(--ffc-border);
    border-radius: .5rem;
    display: inline-flex;
    font-weight: 700;
    gap: .55rem;
    min-height: 44px;
    padding: .35rem .75rem;
    white-space: nowrap;
}

.direction-toggle .form-check-input {
    cursor: pointer;
    height: 1.35rem;
    margin: 0;
    width: 2.65rem;
}

.flashcard {
    min-height: 420px;
}

.flashcard .card-body {
    min-height: 420px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.flashcard-word {
    font-size: clamp(2.25rem, 9vw, 5.5rem);
    line-height: 1.05;
    font-weight: 800;
    overflow-wrap: anywhere;
    max-width: 100%;
}

.flashcard-answer {
    color: var(--ffc-muted);
    font-size: clamp(1.25rem, 5vw, 2.5rem);
    line-height: 1.2;
    overflow-wrap: anywhere;
    max-width: 100%;
}

.icon-btn {
    width: 44px;
    height: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--ffc-border);
}

.complete-check {
    width: 1.7rem;
    height: 1.7rem;
    cursor: pointer;
}

.card-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 52px;
    height: 64px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--ffc-border);
    box-shadow: 0 .25rem .75rem var(--ffc-shadow);
    font-size: 2.25rem;
    line-height: 1;
    z-index: 2;
}

.card-arrow-left {
    left: .75rem;
}

.card-arrow-right {
    right: .75rem;
}

.card-arrow:disabled {
    opacity: .28;
    pointer-events: none;
}

.search-input {
    max-width: 360px;
}

.table td,
.table th {
    vertical-align: middle;
}

#vocabularyTable,
#usersTable,
#vocabularyTable_wrapper,
#usersTable_wrapper,
#vocabularyTable_wrapper .dt-scroll,
#usersTable_wrapper .dt-scroll,
#vocabularyTable_wrapper .dt-scroll-head,
#usersTable_wrapper .dt-scroll-head,
#vocabularyTable_wrapper .dt-scroll-body,
#usersTable_wrapper .dt-scroll-body {
    width: 100% !important;
}

#vocabularyTable_wrapper .dt-scroll-body,
#usersTable_wrapper .dt-scroll-body {
    border-bottom: 1px solid var(--ffc-border);
}

#vocabularyTable_wrapper .dt-layout-row,
#usersTable_wrapper .dt-layout-row {
    row-gap: .75rem;
}

.action-buttons {
    min-width: 260px;
}

.action-buttons .btn-group {
    flex-wrap: wrap;
    justify-content: flex-end;
    gap: .25rem;
}

.action-buttons .btn {
    border-radius: .4rem !important;
}

.toast.text-bg-light,
[data-bs-theme="dark"] .toast.text-bg-light {
    background-color: var(--bs-body-bg) !important;
    color: var(--bs-body-color) !important;
    border-left: .35rem solid var(--ffc-accent);
}

.toast.toast-success { border-left-color: #198754; }
.toast.toast-error { border-left-color: #dc3545; }
.toast.toast-warning { border-left-color: #ffc107; }
.toast.toast-info { border-left-color: #0dcaf0; }

@media (max-width: 575.98px) {
    body {
        padding-bottom: env(safe-area-inset-bottom);
    }

    main.py-4 {
        padding-top: 1rem !important;
        padding-bottom: 1rem !important;
    }

    .container {
        padding-left: max(.85rem, env(safe-area-inset-left));
        padding-right: max(.85rem, env(safe-area-inset-right));
    }

    h1.h3 {
        font-size: 1.45rem;
    }

    .nav-tabs {
        margin-left: -.85rem;
        margin-right: -.85rem;
        padding-left: .85rem;
        padding-right: .85rem;
    }

    .tab-content {
        border-left: 0 !important;
        border-right: 0 !important;
        margin-left: -.85rem;
        margin-right: -.85rem;
        padding-left: .85rem !important;
        padding-right: .85rem !important;
    }

    .metric {
        min-height: 74px;
        padding: .75rem .55rem;
    }

    .metric span {
        font-size: .72rem;
    }

    .flashcard,
    .flashcard .card-body {
        min-height: min(72vh, 420px);
    }

    .flashcard .card-body {
        padding: 4.25rem 3.75rem 1.5rem !important;
    }

    .card-arrow {
        width: 42px;
        height: 58px;
        font-size: 2rem;
    }

    .card-arrow-left {
        left: .35rem;
    }

    .card-arrow-right {
        right: .35rem;
    }

    .flashcard-word {
        font-size: clamp(2rem, 13vw, 3.75rem);
        margin-top: 1.5rem !important;
        margin-bottom: 2rem !important;
    }

    .flashcard-answer {
        font-size: clamp(1.15rem, 7vw, 2rem);
    }

    .flashcard-shell .btn-group[aria-label="Study controls"] {
        display: grid;
        grid-template-columns: repeat(3, minmax(0, 1fr));
        width: 100%;
    }

    .direction-toggle {
        justify-content: center;
        width: 100%;
    }

    .flashcard-shell .btn-group[aria-label="Study controls"] .btn {
        border-radius: .5rem !important;
        margin: 0 .15rem;
    }

    .search-input {
        max-width: none;
    }

    .action-buttons .btn {
        padding-inline: .45rem;
    }

    .table-responsive {
        overflow: visible;
    }

    #vocabularyTable,
    #usersTable {
        border-collapse: separate;
        border-spacing: 0 .75rem;
    }

    #vocabularyTable thead,
    #usersTable thead {
        display: none;
    }

    #vocabularyTable tbody,
    #vocabularyTable tr,
    #vocabularyTable td,
    #usersTable tbody,
    #usersTable tr,
    #usersTable td {
        display: block;
        width: 100%;
    }

    #vocabularyTable tr,
    #usersTable tr {
        background: var(--ffc-panel-bg);
        border: 1px solid var(--ffc-border);
        border-radius: .5rem;
        box-shadow: 0 .25rem .75rem var(--ffc-shadow);
        padding: .65rem;
    }

    #vocabularyTable td,
    #usersTable td {
        border: 0;
        padding: .45rem .25rem;
    }

    #vocabularyTable td::before,
    #usersTable td::before {
        content: attr(data-label);
        color: var(--ffc-muted);
        display: block;
        font-size: .75rem;
        font-weight: 700;
        text-transform: uppercase;
    }

    #vocabularyTable td.action-buttons,
    #usersTable td.action-buttons {
        min-width: 0;
        text-align: left !important;
    }

    #vocabularyTable td.action-buttons::before,
    #usersTable td.action-buttons::before {
        margin-bottom: .35rem;
    }

    .action-buttons .btn-group {
        display: grid;
        grid-template-columns: repeat(2, minmax(0, 1fr));
        width: 100%;
    }

    .modal-dialog {
        margin: .5rem;
    }

    .modal-content {
        max-height: calc(100dvh - 1rem);
        overflow: auto;
    }

    #toastContainer {
        left: .5rem !important;
        right: .5rem !important;
        top: .5rem !important;
        padding: 0 !important;
    }

    #toastContainer .toast {
        width: 100%;
    }

    #vocabularyTable.dataTable thead,
    #usersTable.dataTable thead {
        display: table-header-group;
    }

    #vocabularyTable.dataTable tbody,
    #usersTable.dataTable tbody {
        display: table-row-group;
        width: auto;
    }

    #vocabularyTable.dataTable tr,
    #usersTable.dataTable tr {
        display: table-row;
        width: auto;
    }

    #vocabularyTable.dataTable tr,
    #usersTable.dataTable tr {
        background: transparent;
        border: 0;
        border-radius: 0;
        box-shadow: none;
        padding: 0;
    }

    #vocabularyTable.dataTable td,
    #vocabularyTable.dataTable th,
    #usersTable.dataTable td,
    #usersTable.dataTable th {
        display: table-cell;
        padding: .65rem .55rem;
        width: auto;
    }

    #vocabularyTable.dataTable td::before,
    #usersTable.dataTable td::before {
        content: none;
    }

    #vocabularyTable.dataTable td.action-buttons,
    #usersTable.dataTable td.action-buttons {
        text-align: right !important;
    }
}

@media (min-width: 576px) and (max-width: 991.98px) {
    .flashcard-shell {
        max-width: 760px;
    }

    .flashcard,
    .flashcard .card-body {
        min-height: 480px;
    }

    .flashcard .card-body {
        padding-left: 5rem !important;
        padding-right: 5rem !important;
    }

    .action-buttons {
        min-width: 210px;
    }
}