@media (max-width: 767px) {
    /* --- 0. HIDE DESKTOP, SHOW MOBILE --- */
    .header-desktop,
    .sub-header-desktop,
    .main-content-area-desktop,
    .footer-desktop {
        display: none;
    }

    .header-mobile,
    .sub-header-mobile,
    .main-content-area-mobile,
    .footer-mobile {
        display: block; /* Use block or flex as needed */
    }
    .header-mobile, .footer-mobile { display: flex; }


    /* --- 1. MOBILE HEADER --- */
    .header-mobile {
        position: sticky; top: 0; z-index: 10;
        width: 100%; background-color: #fff; border-bottom: 0.5px solid #dcdcdc; box-sizing: border-box;
        flex-direction: row; align-items: center; justify-content: center;
        text-align: left; font-size: 10px; color: rgba(0, 0, 0, 0.5); font-family: 'NanumSquare', sans-serif;
    }
    .header-mobile .header-inner {
        max-width: 360px;
        width: 100%; 
        display: flex; 
        flex-direction: column; 
        align-items: center; 
        justify-content: flex-start;
        padding: 16px; 
        box-sizing: border-box;
    }
    .header-mobile .parent {
        align-self: stretch; display: flex; flex-direction: row; align-items: center; justify-content: space-between;
    }
    .header-mobile .div {
        display: flex; flex-direction: row; align-items: center; justify-content: center;
    }
    .header-mobile .symbol-parent {
        display: flex; flex-direction: row; align-items: center; gap: 3px;
    }
    .header-mobile .symbol-icon { width: 13.9px; position: relative; height: 13.9px; }
    .header-mobile .logo-bold { width: 34.8px; position: relative; height: 11.8px; }
    .header-mobile .headermenu-parent {
        display: flex; flex-direction: row; align-items: center; justify-content: flex-start; gap: 5px;
    }
    .header-mobile .headermenu {
        display: flex; flex-direction: row; align-items: flex-start; justify-content: flex-start;
        color: #000; cursor: pointer;
    }
    .header-mobile .caption1-nanumsquare { position: relative; line-height: 10.62px; font-weight: 700; }
    .header-mobile .header-div {
        position: relative; font-size: 8.5px; line-height: 10.62px; font-weight: 300; color: rgba(0, 0, 0, 0.4);
    }
    .header-mobile .headermenu2 {
        display: flex; flex-direction: row; align-items: flex-start; justify-content: flex-start; cursor: pointer;
    }

    /* --- 2. MOBILE SUB-HEADER --- */
    .sub-header-mobile {
        width: 100%; position: sticky; top: 44px; z-index: 10;
        background-color: rgba(0, 0, 0, 0.85); display: flex; flex-direction: row;
        align-items: flex-start; justify-content: center;
        padding: 8px 16px; box-sizing: border-box; text-align: center;
        font-size: 10px; color: #fff; font-family: 'NanumSquare', sans-serif;
    }
    .sub-header-mobile .parent {
        flex: 1; 
        max-width: 360px;
        width: 100%;
        display: flex; 
        flex-direction: row; 
        align-items: center; 
        justify-content: space-around; 
        gap: 16px;
    }
    .sub-header-mobile .sub-nav-item { position: relative; cursor: pointer; word-break: keep-all; }
    .sub-header-mobile .sub-nav-item.active { font-weight: 800; color: #fae100; }

    /* --- 3. MOBILE MAIN CONTENT --- */
    .main-content-area-mobile {
        width: 100%; position: relative;
        display: flex; flex-direction: column;
        justify-content: flex-start;
        text-align: left; color: #000; font-family: 'NanumSquare', sans-serif;
        background-color: #fff;
    }
    .main-content-area-mobile .content-section-mobile {
        display: none;
        background-color: #f9f9f9;
        padding: 32px 0;
    }
    .main-content-area-mobile .content-section-mobile.active { display: block; }
    
    .main-content-area-mobile .title {
        max-width: 360px;
        width: 100%;
        margin: 0 auto;
        display: flex; 
        flex-direction: row; 
        align-items: center;
        justify-content: center; 
        padding: 16px 0px; 
        gap: 8px; 
        font-size: 20px;
    }
    .main-content-area-mobile .icon-mobile { width: 24px; position: relative; height: 24px; object-fit: cover; }
    .main-content-area-mobile .text { display: flex; flex-direction: row; align-items: center; justify-content: center; }
    .main-content-area-mobile .title-nanumsquare { position: relative; font-weight: 800; }
    
    .main-content-area-mobile .content-wrapper {
        max-width: 360px;
        width: 100%;
        margin: 0 auto;
        box-sizing: border-box;
        display: flex; 
        flex-direction: column; 
        align-items: flex-start;
        justify-content: flex-start; 
        padding: 0 16px;
        text-align: center; 
        font-size: 14px;
    }
    .main-content-area-mobile .content-inner {
        align-self: stretch; display: flex; flex-direction: column;
        align-items: center; justify-content: flex-start; gap: 32px;
    }

    .main-content-area-mobile .guide-title-mobile {
        border-radius: 75.57px; background-color: #fae100;
        display: flex; flex-direction: row; align-items: center;
        justify-content: center; padding: 9.2px 24.4px;
    }
    .main-content-area-mobile .guide-title-mobile > div { position: relative; font-weight: 800; }
    
    .main-content-area-mobile .steps-wrapper-mobile {
        display: flex; flex-direction: row; align-items: flex-start;
        justify-content: center; gap: 16px; text-align: left; color: #999; width: 100%; max-width: 340px;
    }
    .main-content-area-mobile .step-indicators-mobile { width: 21px; position: relative; flex-shrink: 0; }
    
    .main-content-area-mobile .step-line-mobile {
        position: absolute; left: 9px;
        border-right: 1.5px solid #fae100; box-sizing: border-box;
        width: 1.5px; 
        transition: top 0.3s ease, height 0.3s ease;
    }

    .main-content-area-mobile .step-indicator-mobile {
        position: absolute; left: 0px;
        border-radius: 50%; background-color: #f9f9f9;
        border: 1.5px solid #fae100; box-sizing: border-box;
        width: 21px; height: 21px;
        display: flex; align-items: center; justify-content: center;
        font-size: 11.5px; color: #fae100; font-family: 'KoPubDotum', sans-serif; cursor: pointer; font-weight: 700;
        transition: top 0.3s ease;
    }
    .main-content-area-mobile .step-indicator-mobile.active { background-color: #fae100; color: #fff; }

    .main-content-area-mobile .step-instructions-mobile {
        display: flex; flex-direction: column; align-items: flex-start; justify-content: flex-start; gap: 10px; flex-grow: 1;
        position: relative;
    }
    .main-content-area-mobile .instruction-item-mobile {
        align-self: stretch; border-radius: 6px;
        display: flex; flex-direction: column; align-items: flex-start;
        justify-content: center; padding: 16px;
        font-size: 13px; line-height: 1.5; font-weight: 800; cursor: pointer; position: relative;
    }
    .main-content-area-mobile .instruction-item-mobile.active {
        background-color: #fff; box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    }
    .main-content-area-mobile .instruction-item-mobile.active::before {
        content: ''; position: absolute; left: -10px; top: 50%;
        transform: translateY(-50%); width: 0; height: 0;
        border-top: 8px solid transparent; border-bottom: 8px solid transparent; border-right: 10px solid #fff;
    }
    .main-content-area-mobile .sub-instructions-mobile { padding-left: 10px; margin-top: 5px; font-size: 12px;}

    .main-content-area-mobile .step-image-container-mobile {
        display: none;
        width: 100%;
        margin-top: 24px;
        margin-bottom: 10px;
    }
    .main-content-area-mobile .step-image-container-mobile.active {
        display: block;
    }

    .main-content-area-mobile .video-link-mobile {
        box-shadow: 0.8px 1.6px 3.2px rgba(0, 0, 0, 0.25);
        border-radius: 5.6px; background-color: #fff;
        display: flex; flex-direction: row; align-items: center;
        justify-content: center; padding: 8px 16px; gap: 8px;
        margin-top: 32px;
    }

    .main-content-area-mobile .image-display-mobile {
        align-self: stretch; position: relative;
        height: 480px;
    }
    .main-content-area-mobile .step-image {
        position: absolute; top: 0; left: 0; width: 100%; height: 100%; object-fit: cover; display: none;
    }
    .main-content-area-mobile .step-image.active { display: block; }
    
    #section-app-install-mobile .step-image,
    #section-coupon-mobile .step-image {
        object-fit: contain;
    }
    
    .main-content-area-mobile .qr-downloads-mobile {
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: flex-start;
        gap: 10px;
        width: 100%;
        margin-top: 16px;
    }
    .main-content-area-mobile .qr-downloads-mobile img { width: 140px; }

    /* START: App Install Section Color Logic (Mobile) */
    #section-app-install-mobile .instruction-item-mobile.active:not([data-step="4"]) {
        color: #000;
    }
    #section-app-install-mobile .instruction-item-mobile[data-step="4"].active:not(:has(.sub-instruction-item.active)) > .main-instruction-text {
        color: #000;
    }
    #section-app-install-mobile .sub-instruction-item.active {
        color: #000;
    }
    #section-app-install-mobile .instruction-item-mobile[data-step="4"].active:has(.sub-instruction-item.active) > .main-instruction-text {
        color: #999;
    }
    /* END: App Install Section Color Logic (Mobile) */
    
    /* START: FIX for Coupon & Sticker section color on Mobile */
    #section-coupon-mobile .instruction-item-mobile.active,
    #section-sticker-mobile .instruction-item-mobile.active {
        color: #000;
    }
    /* END: FIX */


    #section-app-install-mobile .ellipse-div {
        position: absolute;
        display: none;
        width: 12%; 
        aspect-ratio: 1 / 1;
        border-radius: 50%;
        background-color: rgba(255, 0, 0, 0.15);
        border: 1.5vw solid #ff0000;
        box-sizing: border-box;
        z-index: 6;
        top: 61%;
        left: 58.5%;
    }
    #section-app-install-mobile .step-image[data-image-for="2"].active ~ .ellipse-div {
        display: block;
    }
    
    #section-app-install-mobile .image-annotation {
        font-size: 13px;
        line-height: 1.4;
    }
    #section-app-install-mobile .image-annotation[data-annotation-for="4.1"] {
        width: 80%;
        top: 16%;
        left: 50%;
        transform: translateX(-50%);
    }
    #section-app-install-mobile .image-annotation[data-annotation-for="4.2"] {
        width: 90%;
        top: 16%;
        left: 50%;
        transform: translateX(-50%);
    }
    #section-app-install-mobile .arrow-group {
        top: 76.5%;
        left: 68%;
        font-size: 12px;
    }
    #section-app-install-mobile .arrow-group .arrow-container {
        height: 24px;
        width: auto;
        gap: 5px;
    }
    #section-app-install-mobile .arrow-group .arrow-annotation-text {
    }
    #section-app-install-mobile .arrow-group .arrow-1,
    #section-app-install-mobile .arrow-group .arrow-2 {
        width: 40px;
    }
    #section-app-install-mobile .step-image[data-image-for="4"].active ~ .arrow-group {
        display: flex;
    }

    #section-coupon-mobile .character-illustration-mobile {
        position: absolute;
        width: 140px;
        left: 0px;
        bottom: 40px;
        z-index: 5;
        display: none;
        object-fit: contain;
    }
    #section-coupon-mobile .step-image[data-image-for="3"].active ~ .character-illustration-mobile {
        display: block;
    }

    #section-sticker-mobile .image-display-wrapper-mobile {
        position: relative;
        width: 90vw;
        height: 90vw;
        max-width: 350px;
        max-height: 350px;
        margin: 0 auto;
    }
    #section-sticker-mobile .image-display-mobile {
        width: 100%;
        height: 100%;
        margin: 0;
        border-radius: 0%;
        background-color: #f9f9f9;
        position: relative;
        overflow: hidden;
    }
    #section-sticker-mobile .step-image {
        object-fit: cover;
        border-radius: 0%;
    }
    #section-sticker-mobile .icon-2,
    #section-sticker-mobile .icon,
    #section-sticker-mobile .img-0128-icon {
        position: absolute;
        margin: 0 !important;
        display: none;
        z-index: 5;
        object-fit: contain;
    }
    #section-sticker-mobile .icon-2 {
        width: 80%;
        top: 50%;
        left: -33%;
        transform: translateY(-15%);
    }
    #section-sticker-mobile .icon {
        width: 55%;
        top: 50%;
        left: -15%;
        transform: translateY(0%);
    }
    #section-sticker-mobile .img-0128-icon {
        width: 50%;
        top: 50%;
        right: -25%;
        transform: translateY(-20%);
    }
    #section-sticker-mobile .image-display-wrapper-mobile:has(.step-image[data-image-for="2"].active) .icon-2[data-overlay-for="2"] {
        display: block;
    }
    #section-sticker-mobile .image-display-wrapper-mobile:has(.step-image[data-image-for="3"].active) .icon[data-overlay-for="3"] {
        display: block;
    }
    #section-sticker-mobile .image-display-wrapper-mobile:has(.step-image[data-image-for="4"].active) .img-0128-icon[data-overlay-for="4"] {
        display: block;
    }
    
    /* --- 4. MOBILE FOOTER --- */
    .footer-mobile {
        flex-direction: column; 
        align-items: center;
        width: 100%; 
        background-color: #fff; 
        border-top: 0.8px solid #dcdcdc; 
        box-sizing: border-box;
        justify-content: flex-start; 
        padding: 24px 16px; 
        text-align: left;
        font-size: 12px; 
        color: #222; 
        font-family: 'NanumSquare', sans-serif;
    }
    .footer-mobile .frame-parent {
        max-width: 360px;
        width: 100%;
        display: flex; 
        flex-direction: column;
        align-items: center; 
        justify-content: flex-start; 
        gap: 16px;
    }
    .footer-mobile .parent {
        display: flex; flex-direction: row; align-items: flex-start; justify-content: flex-start; gap: 16px;
    }
    .footer-mobile b { position: relative; }
    .footer-mobile .frame-group {
        align-self: stretch; display: flex; flex-direction: column;
        align-items: center; justify-content: flex-start; gap: 4.1px;
        font-size: 10.17px; color: rgba(0, 0, 0, 0.85); text-align: center;
    }
    .footer-mobile .frame-container, .footer-mobile .t-070-4252-5571-parent {
        display: flex; flex-direction: row; align-items: flex-start; justify-content: center; flex-wrap: wrap;
    }
    .footer-mobile .wrapper {
        border-right: 0.8px solid #b9b9b9; display: flex; flex-direction: row;
        align-items: center; justify-content: center; padding: 0px 12.5px 0px 0px;
    }
    .footer-mobile .container {
        border-right: 0.8px solid #b9b9b9; display: flex; flex-direction: row;
        align-items: center; justify-content: center; padding: 0px 12.5px;
    }
    .footer-mobile .frame {
        display: flex; flex-direction: row; align-items: center; justify-content: center; padding: 0px 0px 0px 12.5px;
    }
    .footer-mobile .t-070-4252-5571-parent { gap: 18.8px; }
}