body {
    background: #383838;
    color: blanchedalmond;
}

header {
    position: sticky;
    /* width: 100%; */
    background: rgba(21, 76, 119, .5);
}

header>ul>li:nth-child(4) {
    background-color: rgba(0, 0, 0, 0.5);
    border-bottom-right-radius: 1rem;
    border-bottom-left-radius: 1rem;
    box-shadow: 2px 0 4px 0 #c6d9ed;
    color: rgba(21, 76, 119);
    cursor: none;
}

.imgBack {
    height: 56px;
}

#pageA {
    width: 100%;
    height: 100vh;
    --offset: 0px;
    --blur: 2px;
    height: calc(100vh - 4rem);
    display: flex;
    flex-direction: column;
    justify-content: space-around;
}

#pageA>img {
    width: 50%;
    height: 60%;
    margin: 0 auto;
}

#pageA p {
    margin: 0 auto;
    font-weight: bold;
    font-size: 2rem;
    bottom: 5rem;
    color: white;
}

#pageA #bgWrapper img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

#pageA #bgWrapper {
    position: absolute;
    width: 100%;
    height: 100vh;
    perspective: 100px;
    transform-style: preserve-3d;
    top: 0;
    z-index: -1;
    --offset: 0px;
    --blur: 2px;
}

#pageA #bgWrapper>img {
    position: absolute;
    top: 0;
    left: -20px;
    width: 120%;
    height: 100%;
    z-index: -1;
    transform: translate(var(--offset));
    filter: blur(var(--blur));
}

#pageA #bgWrapper>#satellite {
    width: 320px;
    height: auto;
    top: 100px;
    left: 120px;
}

#pageA>p>span {
    cursor: help;
    letter-spacing: 1rem;
    margin: 0 1rem;
}

/* 第二节 */

#beidouIntro {
    width: 100vw;
    height: 100vh;
    padding: 0 5rem;
    background: rgb(21, 21, 22);
    perspective: 10px;
    display: flex;
    justify-content: center;
    align-items: center;
}

#beidouDef {
    flex: 2;
    max-width: 540px;
}

#textContent>h1,
#beidouDef>h1 {
    color: white;
    font-size: 3rem;
    letter-spacing: 1rem;
    /* transform: translateZ(-2px) scale(1.2); */
}

#beidouDef p {
    text-indent: 2em;
    color: white;
    line-height: 2em;
}

#beidouDef a {
    color: white;
    float: right;
    text-decoration: none;
}

#beidouDef a::after {
    content: " →";
}

#beidouDef a:hover {
    -webkit-animation: bounce-left 0.8s both;
    animation: bounce-left 0.8s both;
}

@-webkit-keyframes bounce-left {
    0% {
        -webkit-transform: translateX(-48px);
        transform: translateX(-48px);
        -webkit-animation-timing-function: ease-in;
        animation-timing-function: ease-in;
        opacity: 1;
    }

    24% {
        opacity: 1;
    }

    40% {
        -webkit-transform: translateX(-26px);
        transform: translateX(-26px);
        -webkit-animation-timing-function: ease-in;
        animation-timing-function: ease-in;
    }

    65% {
        -webkit-transform: translateX(-13px);
        transform: translateX(-13px);
        -webkit-animation-timing-function: ease-in;
        animation-timing-function: ease-in;
    }

    82% {
        -webkit-transform: translateX(-6.5px);
        transform: translateX(-6.5px);
        -webkit-animation-timing-function: ease-in;
        animation-timing-function: ease-in;
    }

    93% {
        -webkit-transform: translateX(-4px);
        transform: translateX(-4px);
        -webkit-animation-timing-function: ease-in;
        animation-timing-function: ease-in;
    }

    25%,
    55%,
    75%,
    87%,
    98% {
        -webkit-transform: translateX(0px);
        transform: translateX(0px);
        -webkit-animation-timing-function: ease-out;
        animation-timing-function: ease-out;
    }

    100% {
        -webkit-transform: translateX(0px);
        transform: translateX(0px);
        -webkit-animation-timing-function: ease-out;
        animation-timing-function: ease-out;
        opacity: 1;
    }
}

@keyframes bounce-left {
    0% {
        -webkit-transform: translateX(-48px);
        transform: translateX(-48px);
        -webkit-animation-timing-function: ease-in;
        animation-timing-function: ease-in;
        opacity: 1;
    }

    24% {
        opacity: 1;
    }

    40% {
        -webkit-transform: translateX(-26px);
        transform: translateX(-26px);
        -webkit-animation-timing-function: ease-in;
        animation-timing-function: ease-in;
    }

    65% {
        -webkit-transform: translateX(-13px);
        transform: translateX(-13px);
        -webkit-animation-timing-function: ease-in;
        animation-timing-function: ease-in;
    }

    82% {
        -webkit-transform: translateX(-6.5px);
        transform: translateX(-6.5px);
        -webkit-animation-timing-function: ease-in;
        animation-timing-function: ease-in;
    }

    93% {
        -webkit-transform: translateX(-4px);
        transform: translateX(-4px);
        -webkit-animation-timing-function: ease-in;
        animation-timing-function: ease-in;
    }

    25%,
    55%,
    75%,
    87%,
    98% {
        -webkit-transform: translateX(0px);
        transform: translateX(0px);
        -webkit-animation-timing-function: ease-out;
        animation-timing-function: ease-out;
    }

    100% {
        -webkit-transform: translateX(0px);
        transform: translateX(0px);
        -webkit-animation-timing-function: ease-out;
        animation-timing-function: ease-out;
        opacity: 1;
    }
}

#iframeWrapper {
    /* visibility: hidden; */
    flex: 3;
    padding-left: 5rem;
}

#iframeWrapper>iframe {
    width: 80%;
    height: 27rem;
}

/* 第三页 */
#beidouUse {
    background-color: rgb(56, 56, 56);
    width: 100vw;
    height: 100vh;
    padding: 5rem;
}

#beidouUse #textContent a {
    display: block;
    padding: 1rem 5rem;
    color: whitesmoke;
    text-decoration: none;
}

#beidouUse #textContent>button {
    padding: 1rem 5rem;
    color: white;
    background-color: rgba(0, 0, 0, 0);
    border: none;
    cursor: pointer;
}

#detail {
    background: black;
    display: none;
    width: 540px;
    color: whitesmoke;
    margin: 10rem auto;
    border: 1px whitesmoke solid;
}

#detail>#close>button {
    margin: 0;
    padding: 1rem;
    color: rgb(156, 156, 156);
    background: rgba(0, 0, 0, 0);
    border: none;
}

#detail>#use_detail {
    letter-spacing: .25rem;
    line-height: 2rem;
    text-indent: 2rem;
    margin: 3rem;
}

#detail>div>a {
    color: rgb(180, 180, 180);
    float: right;
}

#imgContainerHolder {
    width: 75%;
    position: relative;
    margin-left: 5rem;
    display: grid;
    grid-template-columns: 1fr 30px 30px 30px 30px 30px 30px 30px 30px 1fr;
    align-items: center;
    justify-items: center;
}

#imgContainer {
    grid-row: 1 / 2;
    grid-column: 1 / 11;
    width: 100%;
    height: 50vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    transform-style: preserve-3d;
    perspective: 700px;
    --position: 1;
    pointer-events: none;
}

#imgContainerHolder::before {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 99;
    background: linear-gradient(90deg, #383838 5%, transparent 40%);
}

#imgContainerHolder::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    background: linear-gradient(-90deg, #383838 5%, transparent 40%);
}

.left_arrow,
.right_arrow {
    z-index: 99;
    grid-row: 1 / 2;
    padding: 5rem;
    cursor: pointer;
}

.left_arrow {
    grid-column: 1 / 2;
}

.right_arrow {
    grid-column: 10 / 11;
}

#beidouUse #imgContainer>div {
    position: absolute;
    --r: calc(var(--position) - var(--offset));
    --abs: max(calc(var(--r) * -1), var(--r));
    transition: all 0.25s linear;
    transform: rotateY(calc(-10deg * var(--r))) translateX(calc(-300px * var(--r)));
    z-index: calc((var(--position) - var(--abs)));
}

#beidouUse #imgContainer h4 {
    letter-spacing: 1rem;
    text-align: center;
    color: white;
}

#imgContainer img {
    width: 35vh;
    height: auto;
    object-fit: cover;
    border-radius: 1rem;
    box-shadow: 4px 4px 4px rgba(0, 0, 0, 0.3);
}

#beidouUse #imgContainer>div:nth-of-type(1) {
    --offset: 1;
}

#beidouUse #imgContainer>div:nth-of-type(2) {
    --offset: 2;
}

#beidouUse #imgContainer>div:nth-of-type(3) {
    --offset: 3;
}

#beidouUse #imgContainer>div:nth-of-type(4) {
    --offset: 4;
}

#beidouUse #imgContainer>div:nth-of-type(5) {
    --offset: 5;
}

#beidouUse #imgContainer>div:nth-of-type(6) {
    --offset: 6;
}

#beidouUse #imgContainer>div:nth-of-type(7) {
    --offset: 7;
}

#beidouUse #imgContainer>div:nth-of-type(8) {
    --offset: 8;
}

#imgContainerHolder>input:nth-of-type(1) {
    grid-column: 2 / 3;
    grid-row: 2 / 3;
}

#imgContainerHolder>input:nth-of-type(2) {
    grid-column: 3 / 4;
    grid-row: 2 / 3;
}

#imgContainerHolder>input:nth-of-type(3) {
    grid-column: 4 / 5;
    grid-row: 2 / 3;
}

#imgContainerHolder>input:nth-of-type(4) {
    grid-column: 5 / 6;
    grid-row: 2 / 3;
}

#imgContainerHolder>input:nth-of-type(5) {
    grid-column: 6 / 7;
    grid-row: 2 / 3;
}

#imgContainerHolder>input:nth-of-type(6) {
    grid-column: 7 / 8;
    grid-row: 2 / 3;
}

#imgContainerHolder>input:nth-of-type(7) {
    grid-column: 8 / 9;
    grid-row: 2 / 3;
}

#imgContainerHolder>input:nth-of-type(8) {
    margin-left: 2rem;
    grid-column: 8 / 10;
    grid-row: 2 / 3;
}

/* 北斗发展 */
#timeline {
    height: 100vh;
    display: flex;
    overflow-x: hidden;
}

#stageIntro {
    flex: 3;
    background-image: url(../image/launch.gif);
    background-size: cover;
    overflow: auto;
    color: black;
}

#stageIntro>div {
    width: 75%;
    background-color: rgba(255, 255, 255, 0.397);
    backdrop-filter: saturate(180%) blur(40px);
    border-radius: 1rem;
    margin: 5rem auto;
    box-shadow: .25rem .25rem rgba(105, 105, 105, 0.5);
    padding: 3rem 5rem;
}

#stageIntro>div>h2 {
    padding-bottom: 1rem;
    border-bottom: rgb(54, 54, 54) 2px solid;
    font-size: 2rem;
    letter-spacing: 1rem;
}

#stageIntro>div>div {
    display: flex;
    justify-content: space-between;
}

#stageIntro>div p {
    flex: 1;
    font-size: 1rem;
}

#stageIntro>div>div>div {
    flex: 1;
    height: 100%;
    object-fit: cover;
}

#stageIntro>div>div>div>img {
    width: 100%;
}

#stageYears {
    flex: 1;
    background-color: #ffffff;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-content: center;
    padding: 4rem 0;
}

#stageYears p {
    width: 100%;
    height: 6rem;
    line-height: 6rem;
    padding-top: 0;
    margin: 0;
    color: black;
    font-size: 2rem;
    font-family: 'Franklin Gothic Medium', 'Arial Narrow', Arial, sans-serif;
    text-align: center;
    transition: all .36s ease-in-out;
}

#stageYears .stageYearsHover:hover {
    font-size: 2rem;
    font-weight: bold;
    text-shadow: .5rem .5rem .75rem rgba(0, 0, 0, 0.3);
    background: rgb(224, 224, 224);
    cursor: pointer;
    transition: all .36s ease-in-out;
}

#stageYears .selectedYear {
    color: white;
    font-size: 3rem;
    font-weight: bolder;
    text-shadow: 1rem 1rem .5rem rgba(0, 0, 0, 0.3);
    cursor: none;
    transition: all .36s ease-in-out;
    background-color: #113c5e;
    border-top-right-radius: 1rem;
    border-bottom-right-radius: 1rem;
}

/* 北斗特点 */
#beidouFeature {
    color: black;
    padding: 5rem 5rem;
    background: #383838;
}

#beidouFeature>h1 {
    color: white;
    font-size: 3rem;
    letter-spacing: 1rem;
}

#beidouFeature>div {
    display: flex;
}

#beidouFeature>div>div {
    flex: 1;
    padding: 0 2rem;
    margin-right: 5rem;
    border: white 2px solid;
    border-radius: 1rem;
    background: rgb(199, 199, 199);
}

#beidouFeature>div>div>h1 {
    letter-spacing: 1rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid white;
}

#beidouFeature>div>div>p {
    line-height: 2rem;
    text-indent: 2rem;
}

#beidouFeature>div>div>img {
    margin-top: 2rem;
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: .5rem;
}