*{
    margin: 0;
    padding: 0;
    font-family: "Noto Serif TC", serif;  /*宋體*/
}

:root{
    --darker-blue : #0b1a37;
    --dark-blue : #0B1E36;
    --light-blue : #0e243e;
    --champagne-gold : #c9a84c;
    --gold-soft : rgba(201, 168, 76, 0.15);
    --gold-line : rgba(201, 168, 76, 0.35);
}
html {
    scroll-behavior: smooth;
}
.is_hidden{
    display: none !important;
}
@keyframes fadeInUp{
    from{
        opacity: 0;
        transform: translateY(18px);
    }
    to{
        opacity: 1;
        transform: translateY(0);
    }
}
body {
    background-color: #0B1E36;
    padding-top: 63px;

    letter-spacing: 4px;
    font-weight: 400;
}
nav {
    display: flex;
    justify-content: space-between;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: rgba(245, 243, 243, 0.85);
    padding: 0.1rem;
    border-bottom: 2px solid #C9A84C;
    box-shadow: 0px 4px 15px rgba(0, 0, 0, 0.7);
    opacity: 0.9;
    height: 58px;
    z-index: 9999;
}
.nav_css{
    display: flex;
    flex-direction: row-reverse;
    gap: 15px;
    align-items: center;
}
.nav_css div{
    font-size: 1.1rem;
    color: rgb(34, 18, 48);
    margin-right: 30px;
    cursor: pointer;
    /*手指*/
    transition: 200ms ease;
    /*過渡動畫*/
}
.nav_css div:hover{
    color: #C9A84C;
    text-shadow: 0px 1px 1px #1c0e1f;
}
.logo_style {
    margin-left: 10px;
    cursor: pointer;
}
.text_TCTC{
    padding-left: 50px;
    color: whitesmoke;
    font-size: 5rem;
    font-weight: 100;
}


/*intro_first_section-----------------------*/

.intro_first_section{
    position: relative;
    z-index: 0;
    height: 100vh;
    width: 100vw;
    background-color: #0B1E36;
    box-shadow: 0px 10px 300px black;

}
.intro_first_section_text1_and_img > div{
    opacity: 0;
    animation: fadeInUp 800ms ease forwards;
}
.intro_first_section_text1_and_img > div:nth-child(1){ animation-delay: 0.05s; }
.intro_first_section_text1_and_img > div:nth-child(2){ animation-delay: 0.18s; }
.intro_first_section_text1_and_img > div:nth-child(3){ animation-delay: 0.30s; }
.intro_first_section_text1_and_img > div:nth-child(4){ animation-delay: 0.42s; }
.intro_first_section_text1_and_img > div:nth-child(5){ animation-delay: 0.50s; }
.intro_first_section_text1_and_img > div:nth-child(6){ animation-delay: 0.58s; }
.intro_first_section_text0-0{
    color: #C9A84C;

    text-shadow: 0px 0px 2px var(--champagne-gold);
    margin-top: 90px;
    margin-bottom: 2px;

    letter-spacing: 6px;

    font-family: "Noto Serif TC", serif;  /*宋體*/
    font-size: small;

}
.intro_first_section_text0-1{
    text-align: center;
    text-shadow: 0px 0px 2px var(--champagne-gold);

    font-family: "Noto Serif TC", serif;  /*宋體*/

    color: #a38941;
    font-size: small;

}
.intro_first_section_text1{
    padding-top: 30px;

}
.intro_first_section_text1-1{
    color: whitesmoke;
    font-family: "Noto Serif TC", serif;  /*宋體*/
    font-size: clamp(2.6rem, 7vw, 5.6rem);

    font-weight: 200;
    letter-spacing: -1px;
    line-height: 0.86;
}
.intro_first_section_text1-2{
    color: lightgray;
    font-size: clamp(2.6rem, 7vw, 5.6rem);
    font-weight: 280;
}
.intro_first_section_text2-1{
        color: whitesmoke;
    font-family: "Noto Serif TC", serif;  /*宋體*/

    text-shadow: 0px 0px 2px var(--champagne-gold);

    font-size: clamp(2.6rem, 7vw, 5.6rem);
    font-weight: 200;
    letter-spacing: -2px;
}
.intro_first_section_text2-1_穩定{
    color: #C9A84C;
    font-family: "Noto Serif TC", serif;  /*宋體*/
    font-size: clamp(2.65rem, 7.1vw, 5.7rem);
    font-weight: 280;
    margin-bottom: 20px;

    text-shadow: 0px 0px 2px var(--champagne-gold);

}
.intro_first_section_text3-1{
    width: 10rem;
    height: 1px;
    background-color: #C9A84C;
    margin-bottom: 60px;
}
.intro_first_section_text4-1{
    font-size: larger;
    color: rgb(190, 181, 181);
    font-family: "Noto Serif TC", serif;  /*宋體*/
    margin-bottom: 100px;
    font-weight: 500;
}
@keyframes ctaGlow{
    0%, 100%{ box-shadow: 0px 0px 4px black, 0px 0px 0px rgba(201,168,76,0); }
    50%{ box-shadow: 0px 0px 4px black, 0px 0px 14px rgba(201,168,76,0.45); }
}
.intro_first_section_text5_button{

    background-color: var(--champagne-gold);
    color: #0B1E36;
    font-family: "Noto Serif TC", serif;  /*宋體*/

    padding: 1rem 2.3rem;

    font-size: 1.5rem;
    font-weight: 400;

    letter-spacing: 4px;

    box-shadow: 0px 0px 4px black;
    border-radius: 5px;

    transition: all 400ms ease;

    margin-bottom: 3rem;

    animation: ctaGlow 3s ease-in-out infinite;

}
.intro_first_section_text5_button:hover{

    padding: 1rem 2.3rem;

    color: var(--champagne-gold);

    background-color: #0B1E36;

    border-color: var(--champagne-gold);
    border-width: 1px;
    border-radius: 5px;

    box-shadow: 0px 0px 5px #C9A84C;
    cursor: pointer;

    animation-play-state: paused;
}

/*intro_second_section-----------------------*/

.intro_second_section{
    position: relative;
    z-index: 1;
    width: 100vw;
    height: 70vh;
    background-color: hsl(214, 60%, 17%);
    box-shadow: 0px 10px 100px rgb(0, 0, 0, 0.6),
                0px -10px 100px rgb(0, 0, 0, 0.4);
}
.intro_second_section_text1{
    padding-left: 50px;
}
.intro_second_section_text1-1{
    color: #C9A84C;
    font-family: "Noto Serif TC", serif;  /*宋體*/
    font-size: 1.3rem;

    margin-left: 5%;
    padding-top: 50px;
}
.intro_second_section_text1-2{
    font-family: "Noto Serif TC", serif;  /*宋體*/
    font-size: 3rem;
    color: lightgray;
}
.intro_second_section_text2{
    padding-left: 210px;
    padding-top: 37px;
}
.intro_second_section_text2-1{
    font-size: 1.2rem;
    line-height: 2.1;
    color: lightgray;
    letter-spacing: 0.2rem;
}

/*intro_third_section-----------------------*/

.intro_third_section_style{
    width: 100vw;
    height: 110vh;
    background-color: #0B1E36;
}
.intro_third_section_text1{
    margin-top: 79px;
}
.intro_third_section_text1-1{
    font-size: 1.3rem;
    padding-left: 50px;
    color: #C9A84C;
    font-family: "Noto Serif TC", serif;  /*宋體*/

}
.intro_third_section_text1-2{
    font-family: "Noto Serif TC", serif;  /*宋體*/
    font-size: 3rem;

    color: lightgray;

    margin-bottom: 3rem;
    padding-left: 50px;
}
.intro_third_section_flex{
    margin: auto;
    
    height: 20rem;
    width: 70rem;

    background-color: var(--darker-blue);

    border: 1px solid rgba(201, 168, 76, 0.2);

}
.intro_footer {
    margin-bottom: 0px;
    background-color: rgb(245, 243, 243);
    border-top: 2px solid var(--champagne-gold);
    width: 100vw;
    padding: 2.2rem 0 1.6rem;
    box-shadow: 0px -1px 15px rgba(0, 0, 0, 0.5);
}

.footer_div{
    display: flex;
    flex-wrap: wrap;
    gap: 80px;
    justify-content: center;
}
.footer_div div{
    margin-top: 40px;
}
.footer_div div:hover{
    cursor: pointer;
    transition: 400ms ease;
    text-shadow: 0px 1px 1px #1c0e1f;
}

.footer_col{
    display: flex;
    flex-direction: column;
    gap: 0.7rem;
}
.footer_col_title{
    margin: 0;
    font-size: 1.05rem;
    font-weight: 500;
    letter-spacing: 1px;
    color: rgb(34, 18, 48);
}
.footer_link{
    position: relative;
    width: fit-content;

    font-size: 0.8rem;
    color: rgb(34, 18, 48);
    text-decoration: none;

    transition: color 300ms ease;
}
.footer_link::after{
    content: "";
    position: absolute;
    left: 0;
    bottom: -3px;
    width: 0%;
    height: 1px;
    background-color: var(--champagne-gold);
    transition: width 300ms ease;
}
.footer_link:hover{
    color: var(--champagne-gold);
}
.footer_link:hover::after{
    width: 100%;
}
.footer_copyright{
    margin-top: 2rem;
    font-size: 0.8rem;
    color: #555;
    letter-spacing: 1px;
    text-align: center;
}
.start_now_image{
    opacity: 0.85;
    margin-top: 50px;
    cursor: pointer;
    width: 200px;
    box-shadow: 0px -1px 5px black;
}
.intro_first_section_text1_and_img{
    display: flex;
    flex-direction: column;
    align-items: center;
}



/* <a> 標籤預設有底線 要清掉 */
a.si-btn,
a.si-scroll-cta {
    text-decoration: none;
    display: inline-flex;
}
section {
scroll-margin-top: 63px; /* 對齊 nav 高度，避免被遮住 */
position: relative;
}
section:not(.intro_first_section)::before{
    content: "";
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: min(60%, 900px);
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--gold-line), transparent);
}

/* 統一所有 section 的「下一頁」按鈕位置：固定貼在底部置中 */
.si-next-wrap {
position: absolute;
left: 50%;
bottom: 36px;
transform: translateX(-50%);
margin: 0;
padding: 0;
}

.si-scroll-cta {
background-color: transparent;
color: var(--champagne-gold);
font-family: "Noto Serif TC", serif;
padding: 9px 24px;
font-size: 1rem;
font-weight: 400;
letter-spacing: 4px;
border: 1px solid var(--champagne-gold);
border-radius: 2px;
box-shadow: 0px 0px 4px rgba(0, 0, 0, 0.5);
transition: all 400ms ease;
cursor: pointer;
}

.si-scroll-cta:hover {
background-color: #C9A84C;
color: #0B1E36;
box-shadow: 0px 0px 8px #C9A84C;
}

/* ===== 新章節：核心功能（獨立 section，不跟介紹文字混在一起）===== */

.intro_features_section {
width: 100vw;
min-height: 70vh;
background-color: var(--darker-blue);
box-shadow: 0px 10px 100px rgba(0, 0, 0, 0.6),
0px -10px 100px rgba(0, 0, 0, 0.4);
padding-top: 79px;
padding-bottom: 130px;
}

.si-feature_grid {
display: flex;
gap: 30px;
padding-left: 50px;
padding-right: 50px;
margin-top: 20px;
flex-wrap: wrap;
}

.si-feature_card {
flex: 1;
min-width: 220px;
background-color: var(--dark-blue);
border: 1px solid rgba(201, 168, 76, 0.2);
border-top: 2px solid var(--gold-line);
padding: 34px 25px 28px;
border-radius: 8px;
position: relative;
transition: all 400ms ease;
cursor: default;
}

.si-feature_card::before{
    content: "";
    position: absolute;
    top: -2px;
    left: 0;
    width: 0%;
    height: 2px;
    background-color: var(--champagne-gold);
    transition: width 400ms ease;
}

.si-feature_card:hover {
transform: translateY(-8px);
border-color: var(--champagne-gold);
box-shadow: 0px 8px 25px rgba(201, 168, 76, 0.25);
}

.si-feature_card:hover::before{
    width: 100%;
}

.si-feature_card:nth-of-type(1)::after,
.si-feature_card:nth-of-type(2)::after,
.si-feature_card:nth-of-type(3)::after{
    position: absolute;
    top: 16px;
    right: 20px;
    font-family: "Playfair Display", serif;
    font-size: 0.85rem;
    color: var(--champagne-gold);
    opacity: 0.6;
    letter-spacing: 1px;
}
.si-feature_card:nth-of-type(1)::after{ content: "01"; }
.si-feature_card:nth-of-type(2)::after{ content: "02"; }
.si-feature_card:nth-of-type(3)::after{ content: "03"; }

.si-feature_icon {
font-size: 1.5rem;
font-weight: 500;
color: whitesmoke;
letter-spacing: 1px;
margin-bottom: 15px;
padding-right: 2rem;
}

.si-feature_title {
color: whitesmoke;
font-size: 1.15rem;
font-weight: 500;
margin-bottom: 12px;
letter-spacing: 2px;
}

.si-feature_desc {
color: rgb(170, 170, 170);
font-size: 0.95rem;
line-height: 1.8;
letter-spacing: 1px;
}

/* ===== 第四章節：難度卡片 ===== */

.intro_third_section_flex {
display: flex;
gap: 25px;
background-color: transparent;
border: none;
padding: 0 20px;
}

.si-difficulty_card {
flex: 1;
height: 100%;

background-color: var(--darker-blue);

border: 1px solid rgba(201, 168, 76, 0.2);
border-radius: 8px;

padding: 35px 30px;

display: flex;
flex-direction: column;

transition: all 400ms ease;
cursor: pointer;

}

.si-difficulty_card:hover {
transform: translateY(-10px);
border-color: var(--champagne-gold);
box-shadow: 0px 10px 30px rgba(201, 168, 76, 0.3);
background-color: var(--light-blue);
}

.si-difficulty_level {
color: var(--champagne-gold);

font-size: 0.9rem;

letter-spacing: 3px;
margin-bottom: 10px;
}

.si-difficulty_name {
color: whitesmoke;

font-size: 1.8rem;
font-weight: 300;

margin-bottom: 20px;
}

.si-difficulty_desc {
color: rgb(170, 170, 170);
font-size: 0.95rem;
line-height: 1.9;
letter-spacing: 1px;
flex-grow: 1;
}

.si-difficulty_wpm {
color: var(--champagne-gold);
font-size: 0.85rem;
letter-spacing: 2px;
margin-top: 20px;
border-top: 1px solid rgba(201, 168, 76, 0.2);
padding-top: 15px;
}

.si-difficulty_card:hover .si-difficulty_wpm{
    border-top-color: rgba(201, 168, 76, 0.4);
}