/* study999-visibility-controls-v1 */

#app section.card button.study999-english-zh-toggle {
    display: inline-flex !important;
    align-items: center !important;
    justify-content: center !important;
    gap: 8px !important;

    position: relative !important;
    width: fit-content !important;
    height: 38px !important;
    min-height: 38px !important;
    box-sizing: border-box !important;

    margin: 0 !important;
    padding: 0 12px !important;

    border: 1px solid #cbd5e1 !important;
    border-radius: 10px !important;

    background: #f1f5f9 !important;
    color: #172554 !important;

    font-size: 14px !important;
    font-weight: 700 !important;
    line-height: 1 !important;
    white-space: nowrap !important;

    cursor: pointer !important;
}

#app section.card button.study999-english-zh-toggle.is-active {
    background: #dbeafe !important;
    border-color: #93c5fd !important;
}

/* 18×18px 白底方框 */
#app section.card button.study999-english-zh-toggle::before {
    content: "" !important;
    display: inline-block !important;
    width: 18px !important;
    height: 18px !important;
    min-width: 18px !important;
    box-sizing: border-box !important;
    flex: 0 0 18px !important;

    border: 2px solid #64748b !important;
    border-radius: 4px !important;
    background: #fff !important;
}

/* 开启后，显示红色勾 */
#app section.card button.study999-english-zh-toggle.is-active::before {
    border-color: #dc2626 !important;
}

#app section.card button.study999-english-zh-toggle.is-active::after {
    content: "✓" !important;
    position: absolute !important;
    left: 12px !important;
    top: 50% !important;
    transform: translateY(-50%) !important;

    display: grid !important;
    place-items: center !important;
    width: 18px !important;
    height: 18px !important;

    color: #dc2626 !important;
    font: 900 18px/1 Arial, sans-serif !important;
    pointer-events: none !important;
}

#app section.card button.study999-english-zh-toggle:focus-visible {
    outline: 2px solid #2563eb !important;
    outline-offset: 3px !important;
}