@media (max-width: 768px) {

    html {
        font-size: 16px;
        overflow-x: hidden;
        width: 100%;
    }

    body {
        -webkit-text-size-adjust: 100%;
        overflow-x: hidden;
        width: 100%;
        
    }

    #nav {
        position: fixed;
        display: flex;
        align-items: center;
        justify-content: space-between;
        height: 58px;
        box-sizing: border-box;
        padding: 0 0.8rem;
        
        z-index: 100010 !important;
        opacity: 1 !important; 
    }

    #nav .logo_style {
        height: 2rem;
        width: auto;
    }

    #nav .nav_css {
        display: none;
    }

    #nav.nav_mobile_open .nav_css {
        display: flex;
        flex-direction: column;
        align-items: stretch; 
        position: fixed;
        top: 0;
        right: 0;
        height: 100vh;
        width: min(80vw, 320px);
        background-color: var(--darker-blue, #0b1a37);
        padding: 5rem 1.5rem 2rem;
        box-shadow: -4px 0 24px rgba(0, 0, 0, 0.4);
        z-index: 100000;
        overflow-y: auto;
        gap: 0.5rem;
    }

    #nav.nav_mobile_open .nav_css > div {
        font-size: 1.15rem;
        padding: 0.9rem 0.5rem;
        border-bottom: 1px solid rgba(255, 255, 255, 0.1);
        color: rgba(255, 255, 255, 0.92) !important;
        margin-right: 0 !important;
        width: 100%;
        box-sizing: border-box;
        text-align: left;
    }

    .tctc_mobile_hamburger {
        display: flex;
        flex-direction: column;
        justify-content: center;
        gap: 5px;
        width: 2rem;
        height: 2rem;
        background: transparent;
        border: none;
        cursor: pointer;
        z-index: 100001;
        flex-shrink: 0;
    }

    .tctc_mobile_hamburger span {
        display: block;
        height: 3px;
        border-radius: 2px;
        background-color: var(--champagne-gold, #c9a84c);
        transition: transform 0.25s ease, opacity 0.25s ease;
    }

    #nav.nav_mobile_open .tctc_mobile_hamburger span:nth-child(1) {
        transform: translateY(8px) rotate(45deg);
    }
    #nav.nav_mobile_open .tctc_mobile_hamburger span:nth-child(2) {
        opacity: 0;
    }
    #nav.nav_mobile_open .tctc_mobile_hamburger span:nth-child(3) {
        transform: translateY(-8px) rotate(-45deg);
    }

    .tctc_mobile_overlay {
        display: none;
        position: fixed;
        inset: 0;
        background: rgba(0, 0, 0, 0.5);
        z-index: 99999;
    }
    #nav.nav_mobile_open ~ .tctc_mobile_overlay {
        display: block;
    }

    .nav_dropdown {
        flex-direction: column !important;
        align-items: flex-start !important;
        width: 100%;
        gap: 0 !important;
    }
    .nav_dropdown_menu {
        display: none !important;
        position: static !important;
        transform: none !important;
        box-shadow: none !important;
        background: transparent !important;
        width: 100%;
    }
    .nav_dropdown.nav_dropdown_open .nav_dropdown_menu {
        display: block !important;
    }
    .nav_dropdown_panel {
        padding-left: 1rem;
        
        background-color: transparent !important;
        box-shadow: none !important;
        border-radius: 0 !important;
        margin-top: 0 !important;
        padding-top: 0.2rem !important;
        padding-bottom: 0.2rem !important;
    }
    .nav_dropdown_item {
        font-size: 1.05rem;
        padding: 0.6rem 0;
        color: rgba(255, 255, 255, 0.75) !important;
    }
    .nav_dropdown_item:hover {
        background-color: transparent !important;
        color: var(--champagne-gold, #c9a84c) !important;
    }
    .nav_dropdown_arrow {
        float: right;
    }

    body {
        letter-spacing: 1px;
    }

    .intro_first_section_text0-0 {
        font-size: 0.68rem;
        margin-top: 5.5rem; 
        letter-spacing: 1px;
        text-align: center;
        width: 100%;
        padding: 0 1rem;
        box-sizing: border-box;
    }
    .intro_first_section_text0-1 { font-size: 0.8rem; text-align: center; }
    .intro_first_section_text1 { padding-top: 1rem; }
    .intro_first_section_text1-1 {
        font-size: 1.7rem;
        line-height: 1.5;
        padding: 0 1rem;
        text-align: center;
    }
    .intro_first_section_text4-1 {
        font-size: 0.85rem;
        margin-bottom: 3rem;
        padding: 0 1.2rem;
        text-align: center;
        line-height: 1.7;
    }
    .intro_first_section_text5_button {
        font-size: 1.1rem;
        padding: 0.8rem 1.8rem;
        letter-spacing: 2px;
    }

    .intro_second_section {
        height: auto;
        min-height: 0;
        padding-bottom: 3rem;
    }
    .intro_second_section_text1 {
        padding-left: 0;
        text-align: center;
    }
    .intro_second_section_text1-1 {
        margin-left: 0;
        padding-top: 2.5rem;
        font-size: 1.05rem;
    }
    .intro_second_section_text1-2 {
        font-size: 1.6rem;
    }
    
    .intro_second_section_text2 {
        padding-left: 1.2rem;
        padding-right: 1.2rem;
        padding-top: 1.5rem;
    }
    .intro_second_section_text2-1 {
        font-size: 0.95rem;
        line-height: 1.9;
        letter-spacing: 0.05rem;
    }

    .intro_features_section {
        padding-top: 3rem;
        padding-bottom: 3rem;
    }
    .intro_third_section_text1 { margin-top: 2.5rem; }
    .intro_third_section_text1-1 {
        font-size: 1.05rem;
        padding-left: 1.2rem;
    }
    .intro_third_section_text1-2 {
        font-size: 1.6rem;
        padding-left: 1.2rem;
        margin-bottom: 1.5rem;
    }
    .intro_second_section_text2-1,
    .intro_third_section_text1-1 {
        font-size: 0.95rem;
        line-height: 1.8;
    }
    .si-feature_grid {
        padding-left: 1.2rem;
        padding-right: 1.2rem;
    }
    .si-difficulty_name { font-size: 1.4rem; }
    .si-difficulty_desc { font-size: 0.88rem; line-height: 1.7; }

    .si-feature_grid,
    .intro_third_section_flex,
    .achv_streak_strip,
    .ranking_selector_row {
        display: flex;
        flex-direction: column !important;
        gap: 1rem;
    }

    .ranking_metric_group {
        display: flex !important;
        flex-direction: row !important;
        flex-wrap: wrap !important;
        justify-content: center !important;
        gap: 0.5rem !important;
    }
    .ranking_mode_tabs {
        justify-content: center !important;
    }

    .si-feature_card,
    .si-difficulty_card {
        width: 100% !important;
        box-sizing: border-box;
    }

    .si-next-wrap {
        position: static !important;
        left: auto !important;
        bottom: auto !important;
        transform: none !important;
        text-align: center;
        margin-top: 2rem;
        padding-bottom: 1.5rem;
    }
    .intro_first_section {
        height: auto !important;
        min-height: 100vh;
        padding-bottom: 2rem;
    }

    .footer_div {
        flex-direction: column;
        align-items: center;
        gap: 1.8rem;
        padding: 0 1.5rem;
        box-sizing: border-box;
    }
    .footer_div div {
        margin-top: 0;
    }
    .footer_col {
        align-items: center;
        text-align: center;
    }
    .intro_footer {
        padding: 2rem 0 1.4rem;
    }

    .intro_third_section_flex {
        width: 100% !important;
        height: auto !important;
        box-sizing: border-box;
    }
    .intro_third_section_style {
        height: auto;
        padding-bottom: 3rem;
    }

    .ranking_container {
        padding: 0 0.8rem;
        box-sizing: border-box;
        margin-top: 4.5rem; 
    }

    .ranking_title {
        font-size: 1.7rem;
    }

    .ranking_total_views {
        top: 4.2rem;
        right: 1rem;
        font-size: 0.65rem;
    }

    .ranking_list_wrap {
        overflow-x: auto;
    }
    .ranking_list_header,
    .ranking_row {
        grid-template-columns: 3.5rem 1fr 6rem 4.5rem;
        min-width: 24rem;
        padding: 0.6rem 0.8rem;
        font-size: 0.82rem;
    }
    .rank_col_rank {
        font-size: 0.9rem;
    }

    .ranking_metric_group .ranking_select {
        font-size: 0.78rem;
        padding: 0.4rem 0.7rem;
    }

    .achv_badge_row {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }
    .achv_badge_name {
        font-size: 1.05rem;
    }

    .profile_avatar_row {
        flex-wrap: wrap;
    }
    .profile_page_title {
        font-size: 1.7rem;
    }

    .vp_player_name {
        font-size: 1.5rem;
    }
    .vp_report_modal {
        padding: 1.3rem 1.1rem;
    }

    .main_lobby_main_frame_row {
        width: 92vw !important;
        flex-direction: column-reverse !important; 
        gap: 1rem !important;
        padding: 0 !important;
        background-color: transparent !important;
        border: none !important;
        box-shadow: none !important;
        margin-bottom: 1rem !important;
    }

    .main_lobby_main_frame_profileblock {
        width: 92vw !important;
        margin-top: 4.8rem !important;
        flex-direction: row !important;
        align-items: center !important;
        gap: 0.8rem !important;
        padding: 0.9rem 1rem !important;
    }
    .profile_avatar_container {
        width: 3rem !important;
        height: 3rem !important;
        flex-shrink: 0;
    }
    .avatar_default_head {
        width: 1.05rem !important;
        height: 1.05rem !important;
        margin-bottom: 2px !important;
    }
    .avatar_default_body {
        width: 3rem !important;
        height: 1.4rem !important;
    }
    .main_lobby_main_frame_player_profile {
        flex-direction: row !important;
        flex-wrap: wrap !important;
        align-items: center !important;
        justify-content: flex-start !important;
        text-align: left;
        background-color: transparent !important;
        border-radius: 0 !important;
        padding: 0 !important;
        gap: 0.5rem 0 !important;
        flex: 1;
        min-width: 0;
    }
    .main_lobby_main_frame_player_profile_left_div {
        flex: 1 1 100% !important;
        align-items: flex-start !important;
        min-width: 0;
        max-width: 100%;
    }
    .main_lobby_main_frame_player_profile_left_div_name {
        display: block;
        font-size: 0.95rem !important;
        max-width: 100% !important;
        white-space: nowrap !important;
        overflow: hidden !important;
        text-overflow: ellipsis;
    }
    .main_lobby_main_frame_player_profile_left_div_username {
        max-width: 60vw;
        display: inline-block;
        vertical-align: bottom;
        white-space: nowrap !important;
        overflow: hidden !important;
        text-overflow: ellipsis;
    }
    .main_lobby_main_frame_player_profile_left_div_rank {
        font-size: 0.7rem !important;
        opacity: 0.7;
    }
    .main_lobby_main_frame_profileblock_wpm,
    .main_lobby_main_frame_profileblock_acc,
    .cg_profileblock_points {
        width: auto !important;
        flex: 1 1 0 !important;
        text-align: center;
        padding-top: 0.5rem;
        margin-top: 0.3rem;
        border-top: 1px solid rgba(var(--accent-rgb, 201, 168, 76), 0.15);
    }

    .main_lobby_main_frame_mode_selector_intro,
    .main_lobby_main_frame_mode_selector {
        width: 92vw !important;
        flex-direction: column !important;
        gap: 1rem !important;
        padding-left: 1rem !important;
        padding-right: 1rem !important;
    }
    .main_lobby_main_frame_map_selector {
        width: 100% !important;
        padding: 1rem !important;
        box-sizing: border-box !important;
    }

    .main_lobby_chapter_selector_text1 {
        position: static !important;
        display: block !important;
        width: 100% !important;
        box-sizing: border-box;
        text-align: center;
        padding: 0.5rem 0.8rem !important;
        margin-bottom: 0.8rem;
        font-size: 0.85rem !important;
        color: var(--champagne-gold, #c9a84c) !important;
        letter-spacing: 1px;
        background-color: rgba(var(--accent-rgb, 201, 168, 76), 0.06);
        border: 1px solid rgba(var(--accent-rgb, 201, 168, 76), 0.35);
        border-radius: 6px;
        cursor: pointer;
        transition: background-color 150ms ease, border-color 150ms ease;
    }
    .main_lobby_chapter_selector_text1:active {
        background-color: rgba(var(--accent-rgb, 201, 168, 76), 0.14);
        border-color: var(--champagne-gold, #c9a84c);
    }
    .main_lobby_chapter_selector_text1::after {
        content: " ▾";
        color: var(--champagne-gold, #c9a84c);
    }
    .main_lobby_main_frame_map_selector.cg_chapter_open .main_lobby_chapter_selector_text1::after {
        content: " ▴";
    }
    .main_lobby_chapter_list_style {
        max-height: 0 !important;
        overflow: hidden !important;
        transition: max-height 260ms ease, opacity 220ms ease;
        opacity: 0;
    }
    .main_lobby_main_frame_map_selector.cg_chapter_open .main_lobby_chapter_list_style {
        max-height: 60rem !important; 
        opacity: 1;
    }

    .main_lobby_mode_beginner,
    .main_lobby_mode_medium,
    .main_lobby_mode_master,
    .main_lobby_mode_beginner_complete,
    .main_lobby_mode_medium_complete,
    .main_lobby_mode_master_complete {
        width: 100% !important;
        max-width: none !important;
        height: auto !important;
        min-height: 0 !important;
        box-sizing: border-box;
        padding: 0.6rem 0.9rem !important;
    }
    .main_lobby_mode_beginner_text1-0 {
        font-size: 0.7rem;
    }
    .main_lobby_mode_beginner_text1-1 {
        font-size: 1.05rem;
        margin: 0.2rem 0;
    }
    .main_lobby_mode_beginner_text1-2 {
        font-size: 0.78rem;
        line-height: 1.5;
    }
    .main_lobby_mode_tag {
        width: 0.7rem !important;
        height: 0.7rem !important;
        top: 0.5rem !important;
        right: 0.5rem !important;
    }

    .main_lobby_main_frame_mode_selector .main_lobby_mode_beginner,
    .main_lobby_main_frame_mode_selector .main_lobby_mode_medium,
    .main_lobby_main_frame_mode_selector .main_lobby_mode_master,
    .main_lobby_main_frame_mode_selector .main_lobby_mode_beginner_complete,
    .main_lobby_main_frame_mode_selector .main_lobby_mode_medium_complete,
    .main_lobby_main_frame_mode_selector .main_lobby_mode_master_complete {
        display: none !important;
        opacity: 0;
        transform: translateY(-4px);
        transition: opacity 220ms ease, transform 220ms ease;
    }
    .main_lobby_main_frame_mode_selector .main_lobby_mode_golden_shadow {
        display: block !important;
        opacity: 1;
        transform: none;
    }
    .main_lobby_main_frame_mode_selector.main_lobby_mode_open .main_lobby_mode_beginner,
    .main_lobby_main_frame_mode_selector.main_lobby_mode_open .main_lobby_mode_medium,
    .main_lobby_main_frame_mode_selector.main_lobby_mode_open .main_lobby_mode_master,
    .main_lobby_main_frame_mode_selector.main_lobby_mode_open .main_lobby_mode_beginner_complete,
    .main_lobby_main_frame_mode_selector.main_lobby_mode_open .main_lobby_mode_medium_complete,
    .main_lobby_main_frame_mode_selector.main_lobby_mode_open .main_lobby_mode_master_complete {
        display: block !important;
        opacity: 1;
        transform: none;
    }
    /* 保險：第一次造訪、還沒選過難度時，三張卡都還沒有 golden_shadow，
       這種情況下不要整組消失變成空白，全部顯示出來讓玩家自己選 */
    .main_lobby_main_frame_mode_selector:not(:has(.main_lobby_mode_golden_shadow)) .main_lobby_mode_beginner,
    .main_lobby_main_frame_mode_selector:not(:has(.main_lobby_mode_golden_shadow)) .main_lobby_mode_medium,
    .main_lobby_main_frame_mode_selector:not(:has(.main_lobby_mode_golden_shadow)) .main_lobby_mode_master,
    .main_lobby_main_frame_mode_selector:not(:has(.main_lobby_mode_golden_shadow)) .main_lobby_mode_beginner_complete,
    .main_lobby_main_frame_mode_selector:not(:has(.main_lobby_mode_golden_shadow)) .main_lobby_mode_medium_complete,
    .main_lobby_main_frame_mode_selector:not(:has(.main_lobby_mode_golden_shadow)) .main_lobby_mode_master_complete {
        display: block !important;
        opacity: 1;
        transform: none;
    }

    .main_lobby_mode_toggle_btn {
        width: 92vw;
        box-sizing: border-box;
        margin: 0 auto 0.6rem;
        padding: 0.5rem 0.8rem;

        text-align: center;
        color: var(--champagne-gold, #c9a84c);
        font-size: 0.85rem;
        letter-spacing: 1px;

        background-color: rgba(var(--accent-rgb, 201, 168, 76), 0.06);
        border: 1px solid rgba(var(--accent-rgb, 201, 168, 76), 0.35);
        border-radius: 6px;
        cursor: pointer;
        transition: background-color 150ms ease, border-color 150ms ease;
    }
    .main_lobby_mode_toggle_btn:active {
        background-color: rgba(var(--accent-rgb, 201, 168, 76), 0.14);
        border-color: var(--champagne-gold, #c9a84c);
    }

    .cg_difficulty_selector {
        width: 92vw !important;
        flex-direction: column !important;
        flex-wrap: nowrap !important;
        gap: 0.6rem !important;
    }
    .cg_difficulty_card {
        min-width: 0 !important;
        width: 100% !important;
        box-sizing: border-box;
        display: none !important;
    }
    .cg_difficulty_card.cg_difficulty_selected {
        display: block !important;
    }
    .cg_difficulty_selector.cg_diff_open .cg_difficulty_card {
        display: block !important;
    }
    .cg_difficulty_toggle_btn {
        width: 92vw;
        box-sizing: border-box;
        margin: 0 auto 0.6rem;
        padding: 0.5rem 0.8rem;

        text-align: center;
        color: var(--champagne-gold, #c9a84c);
        font-size: 0.85rem;
        letter-spacing: 1px;

        background-color: rgba(var(--accent-rgb, 201, 168, 76), 0.06);
        border: 1px solid rgba(var(--accent-rgb, 201, 168, 76), 0.35);
        border-radius: 6px;
        cursor: pointer;
        transition: background-color 150ms ease, border-color 150ms ease;
    }
    .cg_difficulty_toggle_btn:active {
        background-color: rgba(var(--accent-rgb, 201, 168, 76), 0.14);
        border-color: var(--champagne-gold, #c9a84c);
    }

    .main_lobby_difficulty_selector {
        width: 92vw !important;
        max-width: 92vw !important;
        margin-top: 5.5rem !important;
        height: auto !important;
        min-height: 0 !important;
        max-height: 78vh !important;
        overflow-y: auto;
        padding-bottom: 1.2rem !important;
    }
    .main_lobby_difficulty_selector_text1 {
        margin-left: 0 !important;
        padding: 0 1rem;
    }
    .main_lobby_difficulty_selector_text1-1 {
        font-size: 1.5rem !important;
    }
    .main_lobby_difficulty_selector_row {
        flex-direction: column !important;
        width: 90% !important;
        height: auto !important;
        gap: 0.8rem !important;
        padding: 0.8rem 0;
    }
    .main_lobby_difficulty_seletor_easy,
    .main_lobby_difficulty_seletor_medium,
    .main_lobby_difficulty_seletor_hard {
        width: 100% !important;
        height: auto !important;
        margin-left: 0 !important;
        padding-bottom: 1rem;
    }
    .main_lobby_difficulty_Level2_style {
        font-size: 1.3rem !important;
        padding-top: 0.5rem !important;
    }
    .main_lobby_difficulty_easy_intro {
        font-size: 0.82rem !important;
        line-height: 1.6;
    }
    .main_lobby_difficulty_easy_intro2 {
        height: auto !important;
        margin-top: 1rem !important;
        padding-bottom: 0.8rem;
    }
    .main_lobby_difficulty_easy_intro2-1 {
        height: 2.4rem !important;
        margin-top: 0.6rem;
    }

    .nickname_setup_card {
        max-width: 92vw !important;
        padding: 1.8rem 1.3rem !important;
    }
    .nickname_setup_title {
        font-size: 1.35rem;
    }
    .nickname_setup_desc {
        font-size: 0.78rem;
        line-height: 1.7;
    }
    .nickname_setup_input {
        width: 100% !important;
    }
    .nickname_setup_actions {
        flex-direction: column !important;
        gap: 0.6rem !important;
    }
    .nickname_setup_skip_btn,
    .nickname_setup_confirm_btn {
        width: 100%;
        box-sizing: border-box;
    }

    .detail_main_box {
        padding: 5.5vw 4vw !important;
    }
    .detail_ans {
        width: 100% !important;
        margin-left: 0 !important;
        margin-bottom: 3rem;
        font-size: 0.92rem;
        line-height: 1.7;
    }
    .detail_h2 {
        font-size: 1.05rem;
    }
    .detail_h1 {
        font-size: 1.6rem;
    }

    .main_lobby_main_frame_mode_selector_intro {
        width: 1.6rem !important;
        height: 1.6rem !important;
        position: static;
        margin-top: 0.5rem;
    }

    .main_lobby_map_stage {
        padding-right: 2.4rem;
    }

    main, section, .main_lobby_main_frame {
        max-width: 100vw;
        box-sizing: border-box;
    }

    .game_main {
        width: 92vw;
        margin-top: 8.6rem; 
        gap: 1.2rem;
    }

    .game_char_container {
        width: 100%;
        padding: 0.6rem 0.2rem;
        gap: 0.35rem !important;
    }
    .game_char_box {
        width: 1.9rem;
        height: 2.4rem;
        font-size: 1.15rem;
    }

    #game_container_input_id {
        font-size: 1.05rem !important;
        line-height: 1.9 !important;
    }

    .game_top_left_controls {
        top: 4.3rem;
        left: 0.6rem;
        gap: 0.3rem;
    }
    .game_back_btn,
    .game_rank_floating_btn,
    .kb_toggle_btn,
    .sound_toggle_btn,
    .game_retry_fixed_btn {
        width: 1.7rem !important;
        height: 1.7rem !important;
    }
    .game_back_btn img,
    .game_rank_floating_btn img,
    .kb_toggle_btn img,
    .sound_toggle_btn img,
    .game_retry_fixed_btn img {
        height: 1.1rem !important;
    }
    .game_timer_wrap {
        top: 6.4rem; 
        right: 0.6rem;
        gap: 0.4rem;
    }
    .game_timer {
        height: 1.7rem;
        padding: 0 0.7rem;
        font-size: 1rem;
    }
    .countdown_settings_btn {
        width: 1.7rem !important;
        height: 1.7rem !important;
    }

    #typing_img_2 {
        width: 100% !important;
        height: auto !important;
        max-width: 92vw !important;
    }
    #typing_img_1 {
        max-width: 92vw !important;
    }

    .game_stage_name { font-size: 1.5rem; }

    .game_result {
        padding: 1.4rem 1rem;
        width: 92vw;
        box-sizing: border-box;
    }
    .game_result_wpm { font-size: 2.8rem; }
    .game_result_row { gap: 1.2rem; }
    .game_result_stat_num { font-size: 1.5rem; }
    .game_result_share_rank_row {
        flex-direction: column;
        gap: 0.6rem;
        width: 100%;
    }
}