.about-section {
    padding: clamp(100px, 10vw, 200px) 5% clamp(150px, 23vw, 400px);
    background-color: #dbdbdb;
    /*消さない*/
    /* margin-top: -90px; */
    margin-top: -75px;
    color: #333333;
    font-weight: bold;
    position: sticky;
    z-index: 10;
}

.about-bg-text-wrapper {
    position: absolute;
    top: 150px;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: flex-start;
    align-items: flex-start;
    z-index: 1;
    padding-left: 200px;
}

.about-bg-text {
    position: sticky;
    top: clamp(100px, 10vw, 200px);
    font-size: clamp(60px, 14vw, 180px);
    font-weight: 900;
    opacity: 0.1;
    color: #555;
    letter-spacing: clamp(4px, 1vw, 20px);
    white-space: nowrap;
    background: linear-gradient(90deg, #1c2b5a, #22376d, #315699, #1c2b5a);
    background-size: 200% auto;
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    z-index: 2;
}

.about-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    gap: clamp(20px, 5vw, 40px);
    flex-wrap: wrap;
    flex-direction: row;
    position: relative;
    z-index: 2;
}

.about-text {
    flex: 1;
    min-width: 300px;
    order: 0;
}

.about-text h3 {
    font-size: clamp(22px, 4vw, 35px);
    font-weight: bold;
    margin-bottom: 1em;
    margin-top: clamp(150px, 30vw, 330px);
}

.fade-up-heading {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 1s ease-out, transform 1s ease-out;
    will-change: opacity, transform;
}

.fade-up-heading.reveal {
    opacity: 1;
    transform: translateY(0);
}

.intro-text {
    margin-top: clamp(10px, 2vw, 20px);
    margin-bottom: clamp(20px, 3vw, 30px);
    line-height: 1.5;
}

.about-text p {
    font-size: clamp(16px, 2vw, 20px);
    color: #333;
    line-height: 2.2;
}

/* --- data-scroll-fade アニメーション --- */
[data-scroll-fade] {
    opacity: 0;
    filter: blur(20px) brightness(60%) saturate(50%);
    transform: scale(0.95);
    transition:
        opacity 1.6s ease,
        filter 1.6s ease,
        transform 1.6s ease;
    will-change: opacity, filter, transform;
}

[data-scroll-fade].\:visible {
    opacity: 1;
    filter: blur(0) brightness(100%) saturate(100%);
    transform: scale(1);
}

.about-visual {
    flex: 1;
    min-width: 300px;
    position: relative;
    text-align: center;
    order: 1;
}

.about-visual img {
    width: 100%;
    max-width: clamp(180px, 25vw, 300px);
    transform: rotate(-7deg);
    margin-top: clamp(-100px, -20vw, -160px);
}

.vertical-copy {
    writing-mode: vertical-rl;
    text-orientation: mixed;
    position: absolute;
    right: clamp(-80px, -10vw, -100px);
    top: 0;
    font-size: clamp(24px, 5vw, 45px);
    font-weight: bold;
    line-height: 2.2;
    color: #222;
    display: flex;
    align-items: center;
    justify-content: center;
    white-space: nowrap;
}

.vertical-line {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.vertical-line .line {
    display: inline-block;
    margin-bottom: 8px;
    letter-spacing: 25px;
    -webkit-mask-image: linear-gradient(180deg, #000 0%, #000 50%, transparent 100%);
    mask-image: linear-gradient(180deg, #000 0%, #000 50%, transparent 100%);
    -webkit-mask-repeat: no-repeat;
    mask-repeat: no-repeat;
    -webkit-mask-size: 100% 200%;
    mask-size: 100% 200%;
    -webkit-mask-position: 0% 200%;
    mask-position: 0% 200%;
    opacity: 0;
}

.vertical-line .step1 {
    transform: translateY(-300px);
}

.vertical-line .step2 {
    transform: translateY(-70px);
}

.vertical-line .step3 {
    transform: translateY(90px);
}

@keyframes revealLine {
    0% {
        -webkit-mask-position: 0% 200%;
        mask-position: 0% 200%;
        opacity: 0;
    }

    50% {
        opacity: 1;
    }

    100% {
        -webkit-mask-position: 0% 0%;
        mask-position: 0% 0%;
        opacity: 1;
    }
}

.vertical-line .line.reveal {
    animation: revealLine 1.8s cubic-bezier(0.65, 0.05, 0.36, 1) forwards;
}

@media screen and (max-width: 1024px) {
    .about-section {
        margin-top: -65px;
    }

    .about-bg-text-wrapper {
        top: 100px;
        padding-left: 100px;
    }

    .about-container {
        max-width: 1000px;
    }

    .about-visual img {
        max-width: clamp(150px, 20vw, 250px);
        margin-top: clamp(-80px, -15vw, -120px);
    }

    .vertical-copy {
        right: clamp(-30px, -1vw, 10px);
        font-size: clamp(20px, 4vw, 35px);
    }

    .vertical-line .line {
        letter-spacing: 18px;
    }
}

@media screen and (max-width: 768px) {
    .about-section {
        padding-left: 80px;
        padding-right: 80px;
        padding-top: 50px;
        padding-bottom: clamp(150px, 28vw, 340px);
    }

    .about-bg-text-wrapper {
        top: 70px;
        left: 0;
        width: 100%;
        height: 100%;
        padding-left: 0;
        justify-content: center;
        align-items: flex-start;
    }

    .about-bg-text {
        position: sticky;
        top: 200px;
        font-size: clamp(80px, 14vw, 120px);
    }

    .about-inner {
        flex-direction: column;
        gap: 60px;
    }

    .about-text {
        order: 1;
        /* .about-text を後に表示 */
        margin-top: 100px;
        width: 100%;
        text-align: center;
    }

    .about-text h3 {
        margin-top: 0;
    }

    .about-text p {
        font-size: 18px;
    }

    .about-fade-group p {
        display: inline-block;
        text-align: left;
        max-width: 100%;
    }

    /* .about-visual を上に、.about-text を下に配置 */
    .about-visual {
        order: -1;
        /* .about-visual を先に表示 */
        margin-bottom: 0;
        width: 100%;
        display: flex;
        flex-direction: row;
        justify-content: center;
        align-items: center;
        gap: 100px;
        margin-top: 0;
    }

    .about-visual img {
        margin-top: 120px;
        max-width: 250px;
    }

    .vertical-copy {
        position: static;
        writing-mode: vertical-rl;
        text-align: center;
        margin-top: 300px;
        font-size: 30px;
        right: auto;
        left: auto;
        transform: none;
        padding-bottom: 0;
    }

    .vertical-line .step1 {
        transform: translateY(-100px);
    }

    .vertical-line .step2 {
        transform: translateY(80px);
    }

    .vertical-line .step3 {
        transform: translateY(160px);
    }
}

@media screen and (max-width: 480px) {
    .about-section {
        padding: 80px 7% 150px;
    }

    .about-bg-text-wrapper {
        top: 40px;
    }

    .about-bg-text {
        font-size: 60px;
        top: 80px;
    }

    .about-inner {
        gap: 20px;
    }

    .about-text {
        margin-top: 0;
    }

    .about-text h3 {
        font-size: clamp(20px, 4.5vw, 28px);
        margin-bottom: 0.8em;
    }

    .intro-text,
    .about-text p {
        font-size: clamp(14px, 2.5vw, 16px);
        line-height: 1.8;
    }

    .about-visual {
        gap: 30px;
    }

    .about-visual img {
        margin-top: 80px;
        max-width: 180px;
    }

    .vertical-copy {
        margin-top: 200px;
        font-size: clamp(16px, 4vw, 22px);
    }

    .vertical-line .line {
        letter-spacing: 10px;
    }

    .vertical-line .step1 {
        transform: translateY(-140px);
    }

    .vertical-line .step2 {
        transform: translateY(-60px);
    }

    .vertical-line .step3 {
        transform: translateY(0);
    }
}

@media screen and (max-width: 320px) {
    .about-section {
        padding: 80px 12px 150px;
    }

    .about-visual img {
        width: 50%;
        margin-top: 0px;
    }
}