body {
    margin: 0 auto;
    font-family: 'Inter', sans-serif;
}

/* 전체 컨테이너: max-width를 1920으로 제한 (-> 1280으로 변경)하고 가운데 정렬 */
#divContainer.clsContainer {
    width: 100%;
    height: auto;
    max-width: 1280px;
    margin: 0 auto;
    /*border: 1px solid red;*/
    /* 약간그림자 */
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.05), 0 0 6px rgba(0, 0, 0, 0.03);
    /* 미세한 배경색 차이 */
    background-color: #ffffff;
    border-radius: 8px;
}


/*****************************************
divMain 콘텐츠 CSS
 *****************************************/

/*****************************************
 * 섹션1 스타일
 *****************************************/
#divSection1.clsSection.clsCoreGrammarSection1 {
    background-color: #000000;
    color: white;
    padding: 80px 0;
    text-align: center;
}

.clsCoreGrammarSection1Content {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
}

.clsCoreGrammarSection1Title {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 40px;
    color: white;
}

/* 넘버 박스 스타일 */
.clsCoreGrammarNumberBox {
    margin: 30px auto 50px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.clsCoreGrammarNumberContainer {
    background: linear-gradient(35deg, rgba(21, 38, 47, 1), rgba(255, 255, 255, 1));
    border-radius: 20px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
    display: flex;
    align-items: center;
    padding: 15px;
    position: relative;
    max-width: 350px;
}

.clsCoreGrammarNumberColumn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.clsCoreGrammarNumberSeparator {
    color: white;
    font-size: 40px;
    font-weight: bold;
    margin: 0 6px;
    line-height: 0;
    padding-bottom: 35px;
}

.clsCoreGrammarNumberSlot {
    width: 70px;
    height: 90px;
    background-color: #1a1a1a;
    border-radius: 10px;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    overflow: hidden;
    box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.8);
}

.clsCoreGrammarNumberRotator {
    font-size: 60px;
    font-weight: 700;
    color: white;
    text-shadow: 1px 1px 0px rgba(255, 255, 255, 0.2), -1px -1px 0px rgba(0, 0, 0, 0.7);
}

.clsCoreGrammarNumberLabel {
    font-size: 16px;
    font-weight: 600;
    color: white;
    text-align: center;
    background-color: #1a1a1a;
    border-radius: 6px;
    padding: 5px 0;
    width: 70px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
}

/* 학습목표 영역 스타일 */
.clsCoreGrammarGoalsContainer {
    background-color: #3F3F3F;
    padding: 30px;
    border-radius: 8px;
    margin: 0 auto;
    max-width: 700px;
}

.clsCoreGrammarGoalsTitle {
    color: #4CD964;
    font-size: 24px;
    font-weight: 700;
    margin: 0 0 25px 0;
    text-align: center;
}

.clsCoreGrammarGoalsList {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.clsCoreGrammarGoalItem {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    text-align: center;
    margin: 0 auto;
}

.clsCoreGrammarCheckIcon {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
    margin-top: 3px;
}

.clsCoreGrammarGoalItem p {
    margin: 0;
    font-size: 16px;
    line-height: 1.5;
    color: white;
}

/* 섹션1의 반응형 스타일 */
@media screen and (max-width: 1024px) {
    .clsCoreGrammarSection1Title {
        font-size: 26px;
    }

    .clsCoreGrammarNumberSlot {
        width: 65px;
        height: 85px;
    }

    .clsCoreGrammarNumberRotator {
        font-size: 55px;
    }
    
    .clsCoreGrammarNumberLabel {
        width: 65px;
        font-size: 15px;
    }

    .clsCoreGrammarGoalsTitle {
        font-size: 22px;
    }
}

@media screen and (max-width: 768px) {
    #divSection1.clsSection.clsCoreGrammarSection1 {
        padding: 60px 0;
    }

    .clsCoreGrammarSection1Title {
        font-size: 24px;
        margin-bottom: 30px;
    }

    .clsCoreGrammarNumberContainer {
        padding: 15px 10px;
    }

    .clsCoreGrammarNumberSlot {
        width: 55px;
        height: 75px;
    }
    
    .clsCoreGrammarNumberRotator {
        font-size: 48px;
    }
    
    .clsCoreGrammarNumberSeparator {
        /*font-size: 26px;*/
        margin: 0 8px;
    }
    
    .clsCoreGrammarNumberLabel {
        width: 55px;
        font-size: 14px;
    }

    .clsCoreGrammarGoalsContainer {
        padding: 25px 20px;
    }

    .clsCoreGrammarGoalsTitle {
        font-size: 20px;
        margin-bottom: 20px;
    }

    .clsCoreGrammarGoalItem p {
        font-size: 15px;
    }
}

@media screen and (max-width: 480px) {
    #divSection1.clsSection.clsCoreGrammarSection1 {
        padding: 40px 0;
    }

    .clsCoreGrammarSection1Title {
        font-size: 22px;
        margin-bottom: 25px;
    }

    .clsCoreGrammarNumberBox {
        margin: 20px auto 40px;
    }

    .clsCoreGrammarNumberContainer {
        padding: 12px 8px;
    }

    .clsCoreGrammarNumberSlot {
        width: 45px;
        height: 60px;
    }
    
    .clsCoreGrammarNumberRotator {
        font-size: 40px;
    }
    
    .clsCoreGrammarNumberSeparator {
        /*font-size: 22px;*/
        margin: 0 5px;
    }
    
    .clsCoreGrammarNumberLabel {
        width: 45px;
        font-size: 12px;
        padding: 4px 0;
    }

    .clsCoreGrammarGoalsContainer {
        padding: 20px 15px;
    }

    .clsCoreGrammarGoalsTitle {
        font-size: 18px;
        margin-bottom: 15px;
    }

    .clsCoreGrammarGoalItem {
        gap: 8px;
    }

    .clsCoreGrammarCheckIcon {
        width: 16px;
        height: 16px;
    }

    .clsCoreGrammarGoalItem p {
        font-size: 14px;
    }
}

/*****************************************
 * 섹션2 스타일
 *****************************************/
#divSection2.clsSection.clsCoreGrammarSection2 {
    background-color: #021500;
    padding: 80px 0;
    width: 100%;
}

.clsCoreGrammarSection2Content {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.clsCoreGrammarSection2ImageContainer {
    width: 100%;
    max-width: 800px;
    text-align: center;
}

.clsCoreGrammarSection2Image {
    width: 100%;
    height: auto;
    max-width: 100%;
    display: block;
    margin: 0 auto;
}

/* 섹션2의 반응형 스타일 */
@media screen and (max-width: 1024px) {
    #divSection2.clsSection.clsCoreGrammarSection2 {
        padding: 60px 0;
    }

    .clsCoreGrammarSection2ImageContainer {
        max-width: 700px;
    }
}

@media screen and (max-width: 768px) {
    #divSection2.clsSection.clsCoreGrammarSection2 {
        padding: 50px 0;
    }

    .clsCoreGrammarSection2ImageContainer {
        max-width: 600px;
    }
}

@media screen and (max-width: 480px) {
    #divSection2.clsSection.clsCoreGrammarSection2 {
        padding: 40px 0;
    }

    .clsCoreGrammarSection2ImageContainer {
        max-width: 100%;
    }
}

/*****************************************
 * 섹션3 스타일
 *****************************************/
#divSection3.clsSection.clsCoreGrammarSection3 {
    padding: 0 0 80px 0;
    background-color: #ffffff;
}

/* 헤더 영역 스타일 */
.clsCoreGrammarSection3Header {
    background-color: #00CE4E;
    padding: 40px 20px;
    text-align: center;
    color: white;
    margin-bottom: 50px;
}

.clsCoreGrammarSection3Title {
    font-size: 28px;
    font-weight: 700;
    margin: 0 0 15px 0;
}

.clsCoreGrammarSection3SubTitle {
    font-size: 16px;
    line-height: 1.5;
    margin: 0;
}

/* 스텝 그리드 영역 스타일 */
.clsCoreGrammarSection3Grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 20px;
}

.clsCoreGrammarSection3Item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

.clsCoreGrammarSection3StepLabel {
    background-color: #00CE4E;
    color: white;
    border-radius: 20px;
    padding: 5px 15px;
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 15px;
    display: inline-block;
}

.clsCoreGrammarSection3StepTitle {
    font-size: 18px;
    font-weight: 700;
    color: #333;
    margin: 0 0 20px 0;
}

.clsCoreGrammarSection3ImageContainer {
    width: 100%;
    border-radius: 8px;
    overflow: hidden;
    margin-bottom: 15px;
    position: relative;
    aspect-ratio: 16 / 10;
    background-color: transparent;
    display: flex;
    justify-content: center;
    align-items: center;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.clsCoreGrammarSection3Image {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transition: opacity 3.8s ease;
    visibility: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
}

.clsCoreGrammarSection3Image img {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
    border-radius: 0;
}

.clsCoreGrammarSection3Image.active {
    opacity: 1;
    visibility: visible;
}

.clsCoreGrammarSection3StepDesc {
    font-size: 14px;
    color: #666;
    margin: 0;
}

/* Section3 Image Slider Styles */
.clsCoreGrammarSection3ImageSlider {
    position: relative;
    width: 100%;
    height: 100%;
}

.clsCoreGrammarSection3Image {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transition: opacity 0.8s ease;
    visibility: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
}

.clsCoreGrammarSection3Image.active {
    opacity: 1;
    visibility: visible;
}

.clsCoreGrammarSection3Image img {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
    border-radius: 8px;
}

/* 섹션3의 반응형 스타일 */
@media screen and (max-width: 1024px) {
    .clsCoreGrammarSection3Header {
        padding: 35px 20px;
        margin-bottom: 40px;
    }

    .clsCoreGrammarSection3Title {
        font-size: 26px;
    }

    .clsCoreGrammarSection3SubTitle {
        font-size: 15px;
    }

    .clsCoreGrammarSection3Grid {
        gap: 25px;
    }

    .clsCoreGrammarSection3StepTitle {
        font-size: 17px;
    }
}

@media screen and (max-width: 768px) {
    #divSection3.clsSection.clsCoreGrammarSection3 {
        padding: 0 0 60px 0;
    }

    .clsCoreGrammarSection3Header {
        padding: 30px 15px;
        margin-bottom: 35px;
    }

    .clsCoreGrammarSection3Title {
        font-size: 24px;
    }

    .clsCoreGrammarSection3SubTitle {
        font-size: 14px;
    }

    .clsCoreGrammarSection3Grid {
        grid-template-columns: 1fr; /* 한 열로 변경 */
        gap: 30px;
    }

    .clsCoreGrammarSection3StepLabel {
        font-size: 13px;
        padding: 4px 12px;
    }

    .clsCoreGrammarSection3StepTitle {
        font-size: 16px;
        margin-bottom: 15px;
    }

    .clsCoreGrammarSection3ImageContainer {
        max-width: 500px;
        aspect-ratio: 4 / 3; /* 모바일에서 더 좋은 비율 */
    }
}

@media screen and (max-width: 480px) {
    #divSection3.clsSection.clsCoreGrammarSection3 {
        padding: 0 0 50px 0;
    }

    .clsCoreGrammarSection3Header {
        padding: 25px 15px;
        margin-bottom: 30px;
    }

    .clsCoreGrammarSection3Title {
        font-size: 22px;
        margin-bottom: 10px;
    }

    .clsCoreGrammarSection3SubTitle {
        font-size: 13px;
    }

    .clsCoreGrammarSection3Grid {
        gap: 25px;
        padding: 0 15px;
    }

    .clsCoreGrammarSection3StepTitle {
        font-size: 15px;
    }

    .clsCoreGrammarSection3StepDesc {
        font-size: 13px;
    }

    .clsCoreGrammarSection3ImageContainer {
        aspect-ratio: 3 / 2; /* 작은 화면에서의 비율 */
    }
}

/* 넓은 화면에서의 스타일 조정 */
@media screen and (min-width: 992px) {
    .clsCoreGrammarSection3ImageContainer {
        aspect-ratio: 16 / 12;
    }
    
    .clsCoreGrammarSection3Image img {
        max-width: 100%;
        max-height: 100%;
    }
}

@media screen and (min-width: 1200px) {
    .clsCoreGrammarSection3ImageContainer {
        max-width: 500px;
        aspect-ratio: 4 / 3;
    }
    
    .clsCoreGrammarSection3Grid {
        gap: 40px;
    }
}

/*****************************************
 * 섹션4 스타일 (Core Grammar - 비디오 섹션)
 *****************************************/
#divSection4.clsSection.clsCoreGrammarSection4 {
    background-color: #f8f8f8;
    padding: 80px 0;
    font-family: 'Inter', sans-serif;
    width: 100%;
    box-sizing: border-box;
    overflow-x: hidden;
}

.clsCoreGrammarSection4Container {
    max-width: 1100px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 0 20px;
}

.clsCoreGrammarSection4Header {
    text-align: center;
    margin-bottom: 50px;
}

.clsCoreGrammarSection4Title {
    font-size: 28px;
    font-weight: 700;
    color: #333;
    margin: 0;
}

.clsHighlight {
    color: #4CD964;
    font-weight: 700;
}

.clsCoreGrammarVideoContainer {
    padding: 20px 0;
    scroll-margin-top: 100px;
    display: none; /* Hide all sections by default */
}

.clsCoreGrammarVideoContainer.active {
    display: block; /* Show only active section */
}

.clsCoreGrammarVideoGrid {
    display: flex;
    flex-wrap: wrap;
    justify-content: center; /* Center the videos */
    gap: 30px;
    margin: 0 auto; /* Center the grid */
    max-width: 1200px; /* Control maximum width */
}

.clsCoreGrammarVideoItem {
    flex: 1 1 calc(50% - 30px);
    min-width: 280px;
    max-width: 500px;
}

.clsCoreGrammarVideoThumbnail {
    position: relative;
    width: 100%;
    border-radius: 12px;
    overflow: hidden;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

    .clsCoreGrammarVideoThumbnail:hover {
        transform: translateY(-5px);
        box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
    }

        .clsCoreGrammarVideoThumbnail:hover .clsCoreGrammarPlayButton svg circle {
            fill-opacity: 1;
        }

.clsCoreGrammarVideoImg {
    width: 100%;
    height: auto;
    display: block;
}

.clsCoreGrammarPlayButton {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    transition: all 0.3s ease;
}

.clsCoreGrammarVideoTitle {
    font-size: 16px;
    color: #333;
    margin: 15px 0 0 0;
    text-align: center;
}

.clsCoreGrammarMoreButtonContainer {
    margin-top: 30px;
    text-align: center;
}

.clsCoreGrammarMoreButton {
    background: none;
    border: none;
    display: flex;
    flex-direction: column;
    align-items: center;
    cursor: pointer;
    padding: 0;
    transition: transform 0.3s ease;
}

    .clsCoreGrammarMoreButton:hover {
        transform: translateY(-3px);
    }

.clsCoreGrammarMoreIcon {
    width: 40px;
    height: auto;
    margin-bottom: 10px;
}

.clsCoreGrammarMoreButton span {
    font-size: 16px;
    color: #333;
}

/* 비디오 모달 스타일 */
.clsCoreGrammarVideoModal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.85);
    z-index: 1000;
    overflow-y: auto;
}

.clsCoreGrammarModalContent {
    background-color: white;
    margin: 50px auto;
    padding: 20px;
    width: 90%;
    max-width: 1000px;
    border-radius: 10px;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.3);
}

.clsCoreGrammarModalHeader {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: 15px;
    border-bottom: 1px solid #eee;
    margin-bottom: 20px;
}

    .clsCoreGrammarModalHeader h3 {
        font-size: 24px;
        color: #333;
        margin: 0;
    }

.clsCoreGrammarCloseModal {
    background: none;
    border: none;
    font-size: 28px;
    color: #666;
    cursor: pointer;
    transition: color 0.3s ease;
}

    .clsCoreGrammarCloseModal:hover {
        color: #4CD964;
    }

.clsCoreGrammarModalBody {
    padding: 10px 0;
}

.clsCoreGrammarModalVideoGrid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
}

.clsCoreGrammarModalVideoItem {
    width: 100%;
}

/* 커스텀 비디오 플레이어 모달 */
.clsCoreGrammarVideoPlayerModal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.9);
    z-index: 1100;
    align-items: center;
    justify-content: center;
}

    /* 모달이 표시될 때 적용할 스타일 */
    .clsCoreGrammarVideoPlayerModal.active {
        display: flex !important;
        align-items: center !important;
        justify-content: center !important;
    }

.clsCoreGrammarVideoPlayerContainer {
    position: relative;
    width: 90%;
    max-width: 900px;
    background-color: #000;
    border-radius: 8px;
    overflow: hidden;
}

.clsCoreGrammarCloseVideoPlayer {
    position: absolute;
    top: 10px;
    right: 10px;
    background: rgba(0, 0, 0, 0.5);
    border: none;
    color: white;
    font-size: 24px;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    z-index: 10;
    transition: background 0.3s ease;
}

    .clsCoreGrammarCloseVideoPlayer:hover {
        background-color: rgba(255, 255, 255, 0.2);
    }

.clsCoreGrammarCustomVideoPlayer {
    position: relative;
    width: 100%;
}

.clsCoreGrammarVideoElement {
    width: 100%;
    display: block;
}

.clsCoreGrammarVideoControls {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: linear-gradient(to top, rgba(0, 0, 0, 0.7), transparent);
    padding: 15px;
    display: flex;
    align-items: center;
    transition: opacity 0.3s ease;
    opacity: 0;
}

.clsCoreGrammarCustomVideoPlayer:hover .clsCoreGrammarVideoControls {
    opacity: 1;
}

.clsCoreGrammarPlayPauseBtn {
    width: 36px;
    height: 36px;
    background-color: rgba(76, 217, 100, 0.7);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    margin-right: 15px;
    transition: background-color 0.3s ease;
}

    .clsCoreGrammarPlayPauseBtn:hover {
        background-color: rgba(76, 217, 100, 1);
    }

.clsCoreGrammarPauseIcon {
    display: none;
}

.clsCoreGrammarProgressBarContainer {
    flex: 1;
    margin: 0 15px;
}

.clsCoreGrammarProgressBar {
    height: 6px;
    background-color: rgba(255, 255, 255, 0.3);
    border-radius: 3px;
    position: relative;
    cursor: pointer;
}

.clsCoreGrammarProgress {
    height: 100%;
    background-color: #4CD964;
    border-radius: 3px;
    width: 0;
}

.clsCoreGrammarTimeDisplay {
    color: white;
    font-size: 14px;
    margin: 0 15px;
    min-width: 90px;
    text-align: center;
}

.clsCoreGrammarVolumeContainer {
    display: flex;
    align-items: center;
    margin-right: 15px;
}

.clsCoreGrammarVolumeBtn {
    cursor: pointer;
    margin-right: 10px;
}

.clsCoreGrammarVolumeSlider {
    width: 60px;
    height: 6px;
    background-color: rgba(255, 255, 255, 0.3);
    border-radius: 3px;
    position: relative;
    cursor: pointer;
}

.clsCoreGrammarVolumeProgress {
    width: 70%;
    height: 100%;
    background-color: #4CD964;
    border-radius: 3px;
}

.clsCoreGrammarFullscreenBtn {
    cursor: pointer;
}

/* 섹션4의 반응형 스타일 */
@media screen and (max-width: 1024px) {
    #divSection4.clsSection.clsCoreGrammarSection4 {
        padding: 70px 0;
    }

    .clsCoreGrammarSection4Container {
        padding: 0 20px;
    }

    .clsCoreGrammarVideoGrid {
        gap: 20px;
    }

    .clsCoreGrammarVideoTitle {
        font-size: 15px;
    }

    .clsCoreGrammarModalVideoGrid {
        gap: 20px;
    }

    .clsCoreGrammarVideoControls {
        padding: 12px;
    }

    .clsCoreGrammarPlayPauseBtn {
        width: 32px;
        height: 32px;
        margin-right: 10px;
    }

    .clsCoreGrammarTimeDisplay {
        font-size: 13px;
        min-width: 80px;
    }

    .clsCoreGrammarVolumeSlider {
        width: 50px;
    }
}

@media screen and (max-width: 768px) {
    #divSection4.clsSection.clsCoreGrammarSection4 {
        padding: 60px 0;
    }

    .clsCoreGrammarSection4Container {
        padding: 0 15px;
    }

    .clsCoreGrammarSection4Title {
        font-size: 24px;
    }

    .clsCoreGrammarVideoGrid {
        flex-direction: column;
        align-items: center;
        gap: 30px;
    }

    .clsCoreGrammarVideoItem {
        flex: 1 1 100%;
        max-width: 450px;
    }

    .clsCoreGrammarModalVideoGrid {
        grid-template-columns: 1fr;
    }

    .clsCoreGrammarModalHeader h3 {
        font-size: 20px;
    }

    .clsCoreGrammarVideoControls {
        padding: 10px;
    }

    .clsCoreGrammarPlayPauseBtn {
        width: 30px;
        height: 30px;
        margin-right: 8px;
    }

    .clsCoreGrammarTimeDisplay {
        font-size: 12px;
        min-width: 70px;
        margin: 0 8px;
    }

    .clsCoreGrammarVolumeContainer {
        margin-right: 8px;
    }

    .clsCoreGrammarVolumeSlider {
        width: 40px;
    }
}

@media screen and (max-width: 480px) {
    #divSection4.clsSection.clsCoreGrammarSection4 {
        padding: 50px 0;
    }

    .clsCoreGrammarSection4Container {
        padding: 0 10px;
    }

    .clsCoreGrammarSection4Title {
        font-size: 22px;
    }

    .clsCoreGrammarVideoTitle {
        font-size: 14px;
    }

    .clsCoreGrammarMoreIcon {
        width: 30px;
    }

    .clsCoreGrammarMoreButton span {
        font-size: 14px;
    }

    .clsCoreGrammarModalContent {
        margin: 30px auto;
        padding: 15px;
    }

    .clsCoreGrammarVideoControls {
        padding: 8px;
    }

    .clsCoreGrammarPlayPauseBtn {
        width: 28px;
        height: 28px;
        margin-right: 6px;
    }

    .clsCoreGrammarProgressBarContainer {
        margin: 0 8px;
    }

    .clsCoreGrammarTimeDisplay {
        font-size: 11px;
        min-width: 60px;
        margin: 0 6px;
    }

    .clsCoreGrammarVolumeContainer {
        display: none;
    }
}

/* Core Grammar Video Section Styles */
.clsCoreGrammarVideoSection {
    background-color: #E8FFEF;
    padding: 40px 0;
}

.clsCoreGrammarSectionHeading {
    color: #01B144;
    font-size: 28px;
    font-weight: 700;
    text-align: center;
    margin: 30px 0 5px 0;
}

.clsCoreGrammarSectionSubHeading {
    color: #333333;
    font-size: 16px;
    text-align: center;
    margin: 0 0 30px 0;
    font-weight: normal;
}

.clsCoreGrammarVideoGrid {
    display: flex;
    justify-content: center;
    gap: 30px;
    max-width: 1200px;
    margin: 0 auto 50px;
    padding: 0 20px;
}

.clsCoreGrammarVideoItem {
    width: 100%;
    max-width: 480px;
}

.clsCoreGrammarVideoThumbnail {
    position: relative;
    width: 100%;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    aspect-ratio: 16/9;
    cursor: pointer;
    transition: transform 0.3s ease;
}

.clsCoreGrammarVideoThumbnail:hover {
    transform: translateY(-5px);
}

.clsCoreGrammarVideoImg {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.clsCoreGrammarPlayButton {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    cursor: pointer;
    transition: all 0.3s ease;
}

.clsCoreGrammarPlayButton svg circle {
    transition: fill-opacity 0.3s ease;
}

.clsCoreGrammarVideoThumbnail:hover .clsCoreGrammarPlayButton svg circle {
    fill-opacity: 1;
}

.clsCoreGrammarVideoTitle {
    font-size: 16px;
    font-weight: 600;
    color: white;
    text-align: center;
    margin: 15px 0 0;
}

/* Video Player Modal */
.clsCoreGrammarVideoPlayerModal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.9);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.clsCoreGrammarVideoPlayerContainer {
    position: relative;
    width: 90%;
    max-width: 900px;
    background-color: #000;
    border-radius: 8px;
    overflow: hidden;
}

.clsCoreGrammarCloseVideoPlayer {
    position: absolute;
    top: 10px;
    right: 10px;
    background: rgba(0, 0, 0, 0.5);
    border: none;
    color: white;
    font-size: 24px;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    z-index: 10;
    transition: background 0.3s ease;
}

.clsCoreGrammarCloseVideoPlayer:hover {
    background-color: rgba(255, 255, 255, 0.2);
}

.clsCoreGrammarCustomVideoPlayer {
    position: relative;
    width: 100%;
}

.clsCoreGrammarVideoElement {
    width: 100%;
    display: block;
}

.clsCoreGrammarVideoControls {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: linear-gradient(to top, rgba(0, 0, 0, 0.7), transparent);
    padding: 15px;
    display: flex;
    align-items: center;
    transition: opacity 0.3s ease;
    opacity: 0;
}

.clsCoreGrammarPlayPauseBtn {
    cursor: pointer;
    margin-right: 15px;
}

.clsCoreGrammarPauseIcon {
    display: none;
}

.clsCoreGrammarProgressBarContainer {
    flex: 1;
    margin: 0 15px;
}

.clsCoreGrammarProgressBar {
    height: 5px;
    background-color: rgba(255, 255, 255, 0.3);
    border-radius: 3px;
    position: relative;
    cursor: pointer;
}

.clsCoreGrammarProgress {
    height: 100%;
    background-color: #4CD964;
    border-radius: 3px;
    width: 0;
}

.clsCoreGrammarTimeDisplay {
    color: white;
    font-size: 14px;
    margin: 0 15px;
    min-width: 90px;
    text-align: center;
}

.clsCoreGrammarVolumeContainer {
    display: flex;
    align-items: center;
    margin-right: 15px;
}

.clsCoreGrammarVolumeBtn {
    cursor: pointer;
    margin-right: 10px;
}

.clsCoreGrammarVolumeSlider {
    width: 60px;
    height: 5px;
    background-color: rgba(255, 255, 255, 0.3);
    border-radius: 3px;
    position: relative;
    cursor: pointer;
}

.clsCoreGrammarVolumeProgress {
    width: 70%;
    height: 100%;
    background-color: #4CD964;
    border-radius: 3px;
}

.clsCoreGrammarFullscreenBtn {
    cursor: pointer;
}

/* Responsive Styles */
@media (max-width: 992px) {
    .clsCoreGrammarSectionHeading {
        font-size: 26px;
    }
    
    .clsCoreGrammarSectionSubHeading {
        font-size: 15px;
    }
}

@media (max-width: 768px) {
    .clsCoreGrammarVideoSection {
        padding: 30px 0;
    }
    
    .clsCoreGrammarSectionHeading {
        font-size: 24px;
        margin: 25px 0 5px;
    }
    
    .clsCoreGrammarSectionSubHeading {
        font-size: 14px;
        margin: 0 0 20px;
    }
    
    .clsCoreGrammarVideoGrid {
        flex-direction: column;
        align-items: center;
        gap: 25px;
        margin-bottom: 30px;
    }
    
    .clsCoreGrammarVideoItem {
        max-width: 500px;
    }
    
    .clsCoreGrammarVideoTitle {
        font-size: 15px;
    }
    
    .clsCoreGrammarTimeDisplay {
        font-size: 12px;
        min-width: 70px;
    }
    
    .clsCoreGrammarVolumeSlider {
        width: 40px;
    }
}

@media (max-width: 480px) {
    .clsCoreGrammarVideoSection {
        padding: 20px 0;
    }
    
    .clsCoreGrammarSectionHeading {
        font-size: 20px;
        margin: 20px 0 5px;
    }
    
    .clsCoreGrammarSectionSubHeading {
        font-size: 13px;
        margin: 0 0 15px;
        padding: 0 10px;
    }
    
    .clsCoreGrammarVideoGrid {
        gap: 20px;
        margin-bottom: 25px;
    }
    
    .clsCoreGrammarVideoTitle {
        font-size: 14px;
    }
    
    .clsCoreGrammarPlayButton svg {
        width: 50px;
        height: 50px;
    }
    
    .clsCoreGrammarVolumeContainer {
        display: none;
    }
}

/* Navigation Menu styles */
.clsCoreGrammarNavMenu {
    display: flex;
    justify-content: center;
    margin-bottom: 30px;
    flex-wrap: wrap;
    gap: 15px;
}

.clsCoreGrammarNavItem {
    flex: 0 0 calc(25% - 11.25px);
    max-width: 220px;
    box-sizing: border-box;
    display: flex;
    flex-direction: row;
    align-items: center;
    text-decoration: none;
    background-color: #FFFFFF;
    color: #000000;
    border: 0px solid #4CD964;
    border-radius: 10px;
    padding: 12px 15px;
    transition: all 0.3s ease;
    text-align: left;
}

.clsCoreGrammarNavItem img {
    max-width: 40px;
    height: auto;
    margin-right: 10px;
}

.clsCoreGrammarNavItem span {
    font-size: 16px;
    font-weight: 600;
}

.clsCoreGrammarNavItem:hover, 
.clsCoreGrammarNavItem.active {
    background-color: #4CD964;
    color: white;
    border-color: #4CD964;
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.clsCoreGrammarVideoContainer {
    padding: 20px 0;
    scroll-margin-top: 100px;
}

/* Media queries for responsive design */
@media screen and (max-width: 1024px) {
    .clsCoreGrammarNavMenu {
        justify-content: center;
        gap: 10px;
    }
    
    .clsCoreGrammarNavItem {
        flex-basis: calc(25% - 7.5px);
        max-width: 200px;
        padding: 10px 12px;
    }
}

/* New breakpoint for 2 columns */
@media screen and (max-width: 890px) {
    .clsCoreGrammarNavMenu {
        gap: 15px;
    }
    .clsCoreGrammarNavItem {
        flex-basis: calc(50% - 7.5px);
        max-width: 300px;
        min-width: 140px;
        padding: 10px 12px;
    }
     .clsCoreGrammarNavItem span {
        font-size: 15px;
    }
}

@media screen and (max-width: 768px) {
     .clsCoreGrammarNavMenu {
        gap: 10px;
    }
    .clsCoreGrammarNavItem {
        flex-basis: calc(45% - 5px);
        max-width: none;
        padding: 8px 12px;
    }
    
    .clsCoreGrammarNavItem img {
        max-width: 35px;
    }
    
    .clsCoreGrammarNavItem span {
        font-size: 14px;
    }
}

@media screen and (max-width: 480px) {
    .clsCoreGrammarNavMenu {
        flex-direction: column;
        align-items: center;
        gap: 10px;
    }
    
    .clsCoreGrammarNavItem {
        width: 90%;
        padding: 10px 15px;
        flex-basis: auto;
    }
    
    .clsCoreGrammarNavItem img {
        margin-right: 15px;
        max-width: 30px;
    }
}