body {
    margin: 0;
    padding: 0;
    background: url('image/bg.jpg') no-repeat center top; /* 修改这里 */
    background-size: cover;
    min-height: 100vh;
    position: relative;
    overflow-y: auto; /* 允许整体滚动 */
}

.bottom-bar {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 160px;
    background: #ffffff00;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1;
}

.download-btn img {
    max-height: 140px;
    width: auto;
    transition: opacity 0.3s;
}

/* APP内部弹窗样式 */
#appTipModal {
    display: none;
    position: fixed;
    left: 0;
    top: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(0,0,0,0.5);
    z-index: 9999;
}
#appTipModal .modal-content {
    position: absolute;
    top: 28%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 582px;      /* 291*2 */
    height: 406px;     /* 203*2 */
    background: url('image/ui_tips.png') no-repeat center center;
    background-size: 100% 100%;
    border-radius: 24px;
    box-shadow: 0 8px 48px rgba(0,0,0,0.15);
    padding: 48px 48px 48px 48px; /* 原来32/24/24/24*2 */
    box-sizing: border-box;
}
#appTipModal .modal-title {
    font-size: 35px;      /* 20*2 */
    font-weight: bold;
    margin-bottom: 66px;  /* 18*2 */
    text-align: center;
    color: #333;
}
#appTipModal .modal-desc {
    font-size: 32px;      /* 16*2 */
    color: #333;
    text-align: left;
}
#appTipModal .modal-step {
    display: flex;
    align-items: center;
    margin-bottom: 24px;  /* 12*2 */
}
#appTipModal .step-icon {
    width: 44px;          /* 22*2 */
    height: 44px;         /* 22*2 */
    margin-right: 16px;   /* 8*2 */
}
#appTipModal .modal-arrow {
    position: absolute;
    left: calc(50% + 391px); /* 框右边 */
    top: calc(28% - 453px);  /* 框上边，203px为框高的一半 */
    transform: translate(-100%, 0); /* 箭头左边对齐框右边 */
    width: 192px;
    height: 226px;
    z-index: 2;
    pointer-events: none;
}
#appTipModal .close-btn {
    position: absolute;
    left: 50%;
    top: calc(28% + 240px); /* 原120*2，弹窗底部下方，微调 */
    transform: translateX(-50%);
    background: transparent;
    border: none;
    padding: 0;
    cursor: pointer;
    z-index: 2;
}
#appTipModal .close-btn img {
    width: 48px;          /* 24*2 */
    height: 46px;         /* 23*2 */
    display: block;
}