.first-login {
    padding: 0 0 20px;
    position: relative;
}

.first-login__container {
    display: flex;
    justify-content: center;
    align-items: center;
}

.first-login__bg-subtitle {
    position: absolute;
    left: 0;
    top: 0;
    transform: translate(0, -20%);
    width: 100%;
    z-index: 1;
    object-fit: contain;
}

/* Left Side: Image Display */
.first-login__left {
    flex: 1;
    position: relative;
    max-width: 460px;
    height: 480px;
    margin: 0 50px;
    z-index: 2;
}

.first-login__triangle {
    position: absolute;
    z-index: -1;
    bottom: 0;
    left: 50%;
    transform: translate(-50%, 0);
    width: 90%;
    height: 90%;
    transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    transform-origin: center center;
}

.first-login__image-container {
    position: relative;
    width: 100%;
    aspect-ratio: 9/16;
    overflow: hidden;
}

.first-login__image {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: auto;
    object-fit: cover;
    opacity: 0;
    transition: opacity 0.5s ease-in-out;
    pointer-events: none;
}

.first-login__image--active {
    opacity: 1;
    pointer-events: auto;
}

.first-login__right {
    flex: 1;
    max-width: 500px;
    z-index: 2;

}

/* Step Indicators */
.first-login__steps {
    display: flex;
    align-items: center;
    gap: 0;
    margin-top: 10px;
    width: 100%;
}

.first-login__step-btn {
    width: 34px;
    height: 34px;
    border: none;
    background: transparent;
    padding: 0;
    cursor: pointer;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    flex-shrink: 0;
}

.first-login__step-circle {
    width: 34px;
    height: 34px;
    border-radius: 50%;
    background: #a6a6a6;
    display: flex;
    align-items: center;
    justify-content: center;
    /* font-family: "Roboto", Helvetica; */
    font-weight: 700;
    font-size: 18px;
    color: #ffffff;
    transition: all 0.3s ease;
    box-shadow: 0px 2px 8px rgba(0, 0, 0, 0.1);
}

.first-login__step-btn--active .first-login__step-circle {
    background: linear-gradient(166deg, rgba(237, 85, 116, 1) 0%, rgba(217, 54, 87, 1) 100%);
    box-shadow: 0px 4px 15px rgba(217, 54, 87, 0.4);
    transform: scale(1.1);
}

.first-login__step-line {
    flex: 1;
    height: 2px;
    background: #a6a6a6;
    min-width: 60px;
    max-width: 77px;
    transition: all 0.3s ease;
    margin: 0 6px;
}

.first-login__step-line--active {
    background: linear-gradient(166deg, rgba(237, 85, 116, 1) 0%, rgba(217, 54, 87, 1) 100%);
}

/* Responsive Design */
@media (max-width: 1099px) {
    .first-login__container {
        flex-direction: column-reverse;
        gap: 24px;
    }

    .first-login__left {
        width: 90%;
    }

    .first-login__image-container {
        aspect-ratio: 1;
    }

    .first-login__right {
        max-width: 100%;
        display: flex;
        flex-direction: column;
        align-items: center;
    }

    .first-login__steps {
        justify-content: center;
    }
}

@media (min-width: 1100px) {
    .first-login__step-btn:hover .first-login__step-circle {
        background: #d93657;
        transform: scale(1.1);
    }
}

/* 1. 設定初始狀態：透明且位移 */
[sto] [sto-sub], [sto] {
  opacity: 0;
  transform: translateY(40px); /* 往下位移 40px */
  transition: all 0.8s ease-out; /* 動畫持續 0.8 秒 */
}

/* 2. 設定觸發狀態：回到原位並顯示 */
[sto].active, 
[sto].active [sto-sub] {
  opacity: 1;
  transform: translateY(0);
}

/* 3. (進階) 讓子元素有先後順序的飛入感 (Stagger) */
[sto].active [sto-sub]:nth-child(2) {
  transition-delay: 0.2s;
}
[sto].active [sto-sub]:nth-child(3) {
  transition-delay: 0.4s;
}