.main {
  position: relative;
}

.main-content {
  margin-top: -100vh;
  /* overflow: hidden; */
}

.nav {
  position: sticky;
  top: 0;
  left: 3.4vw;
  width: 200px;
  height: 100vh;
  z-index: 1000;
  display: flex;
  align-items: center;
  padding-bottom: 6%;
}

.nav-wrap {
  position: relative;
}

.nav-line {
  width: 1px;
  height: 150px;
  background: #DDDDDD;
}

.nav ul {
  position: absolute;
  top: 0;
  left: 0;
  display: flex;
  flex-direction: column;
  row-gap: 75px;
}

.nav ul li {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
}

.nav ul li::before {
  content: "";
  position: absolute;
  width: 10px;
  height: 10px;
  background: #2C66EF;
  border-radius: 50%;
  transform: scale(0);
  opacity: 0.2;
  transition: all 0.3s;
}

.nav ul li.active::before {
  transform: scale(2);
}

.nav ul li .dot {
  position: absolute;
  width: 10px;
  height: 10px;
  background: #DDDDDD;
  border-radius: 50%;
  transition: all 0.3s;
}

.nav ul li.active .dot {
  background: #2C66EF;
}

.nav ul li span {
  width: 100px;
  position: absolute;
  left: 28px;
  font-size: 1.125rem;
  color: #868686;
  transition: all 0.3s;
}

.nav ul li.active span {
  font-weight: 500;
  color: #2C66EF;
}



/* =========================================
   产品优势
========================================= */
.product-intro {
  background: url(../images/gas-cylinder-bg.jpg) no-repeat center / cover;
}

.product-intro .container {
  
  width: 64.2%;
  padding: 67.5px 0;
}

.product-intro-title {
  font-size: 3.375rem;
  font-weight: bold;
  text-align: center;
}

.product-intro-grid {
  position: relative;
  margin-top: 61.5px;
  display: flex;
  flex-direction: column;
  row-gap: 30px;
}

.card-row {
  display: flex;
  column-gap: 60px;
  position: relative;
}

.card-outline {
  width: 370px;
  height: 191px;
  background: linear-gradient(0deg, #F3F6FD 0%, #EDF3FC 100%);
  box-shadow: 2px 1px 13px 0px rgba(0,51,154,0.05), -5px -3px 26px 1px rgba(97,136,254,0.02);
  border-radius: 15px;
  border: 2px solid #FFFFFF;
  padding: 14px 16px;
  font-size: 1.5rem;
  font-weight: 500;
  transition: .3s;
}

.card-outline:hover {
  transform: scale(1.05);
  /* box-shadow: 2px 1px 13px 0px rgba(0,51,154,0.05), -5px -3px 26px 1px rgba(97,136,254,0.02); */
}

.card-outline > p {
  height: 100%;
  background: #E2ECFF;
  border-radius: 15px;
  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;
}

.maintenance .card-outline > p {
  background: #E2E5FF;
}

.iot .card-outline > p {
  background: #DFECF6;
}

.card-outline .white-card {
  height: 100%;
  background: linear-gradient(178deg, #FFFFFF 0%, #FFFFFF 2%, #FFFFFF 100%);
  box-shadow: 2px 1px 13px 0px rgba(0,51,154,0.1), -5px -3px 26px 1px rgba(97,136,254,0.02);
  border-radius: 15px;
  border: 2px solid #E1ECFF;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 14px;
  text-align: center;
}

.card-outline-large {
  width: 370px;
  height: 458px;
  /* background: linear-gradient(0deg, #F3F6FD 0%, #EDF3FC 100%); */
  
  /* box-shadow: 2px 1px 13px 0px rgba(0,51,154,0.05), -5px -3px 26px 1px rgba(97,136,254,0.02); */
  /* border-radius: 15px; */
  /* border: 2px solid #FFFFFF; */
  /* padding: 17px 16px; */
  font-size: 2.125rem;
  font-weight: 500;
  position: absolute;
  right: -5px;
  top: calc(50% - 229px);
  transition: .3s;
}

.card-outline-large:hover {
  transform: scale(1.05);
}

.card-outline-large .text {
  height: 100%;
  color: #FFFFFF;
  /* background: linear-gradient(0deg, #5895FF 0%, #94BBFF 100%); */
  /* box-shadow: 2px 1px 13px 0px rgba(0,51,154,0.1), -5px -3px 26px 1px rgba(97,136,254,0.02); */
  /* border-radius: 15px; */
  /* border: 2px solid #E1ECFF; */
  display: flex;
  flex-direction: column;
  /* justify-content: center; */
  align-items: center;
  padding-top: 113.5px;
}

.card-outline-large.gas {
  background: url(../images/gas-card-bg.png) no-repeat center / cover;
}

.card-outline-large.maintenance {
  background: url(../images/main-card-bg.png) no-repeat center / cover;
}

.card-outline-large.iot {
  background: url(../images/iot-card-bg.png) no-repeat center / cover;
}

.arrow-icon {
  display: flex;
  width: 87px;
  position: absolute;
  left: 29.3%;
  top: calc(50% - 20px);
  z-index: 500;
}

.arrow-icon.merge {
  left: 64.5%;
  z-index: 1000;
}



/* =========================================
   产品功能
========================================= */
.tab-content {
  padding-top: 33px;
}

.product-function-title {
  text-align: center;
}

.product-function-title > h2 {
  font-size: 2.75rem;
  font-weight: 500;
  color: #363636;
}

.product-function-title > p {
  font-size: 0.875rem;
  font-weight: 500;
  color: #868686;
}

.product-tabs {
  margin-top: 31.5px;
  margin-left: 335px;
  margin-right: 335px;
  display: flex;
  justify-content: space-between;
  font-size: 1.5rem;
  font-weight: bold;
  color: #363636;
}

.product-tab-btn {
  padding: 14px 65px;
  cursor: pointer;
  transition: color 0.3s ease;
}

.product-tab-btn:hover {
  color: #2C66EF;
  transform: scale(1.05);
}

.product-tab-btn.active {
  color: #2C66EF;
  border-bottom: 2px solid;
  transform: scale(1.05);
}

.product-function .product-tab-content {
  padding: 77px 0 85px 309px;
  /* background-color: #ECF4FD; */
  background: url(../images/gas-cylinder-bg.jpg) no-repeat center / cover;
  display: flex;
  /* opacity: 1; */
  column-gap: 58px;
}

.product-function .product-tab-content.active {
  display: flex;
  opacity: 1;
}


.product-function .product-tab-content .card-list {
  display: flex;
  flex-direction: column;
  row-gap: 28px;
}

.product-function-card {
  width: 390px;
  height: 179px;
  background-color: #FFFFFF;
  border-radius: 15px;
  color: #606060;
  padding-top: 20px;
  transition: .3s;
}

.product-function-card:hover {
  transform: scale(1.05);
  box-shadow: 2px 1px 13px 0px rgba(0,51,154,0.05), -5px -3px 26px 1px rgba(97,136,254,0.02);
}

.product-function-card > h3 {
  font-size: 1.25rem;
  color: #363636;
  padding-left: 11px;
  border-left: 4px solid #2C66EF;
  margin-left: 24px;
}

.product-function-card > p {
  margin-top: 23px;
  margin-left: 39px;
  line-height: 37px;
}

.product-img {
  width: 867px;
  /* border: 1px dotted; */
  display: flex;
  justify-content: center;
  align-items: center;
  transition: .3s;
}

.product-img:hover {
  transform: scale(1.05);
}

/* =========================================
   总结
========================================= */
.summary {
  padding: 132px 0;
  background: #ECF4FD;
}

.summary .container {
  width: 72.6%;
  display: flex;
  justify-content: center;
  column-gap: 25px;
}

.summary .circle-outline {
  width: 294px;
  height: 294px;
  background: linear-gradient(0deg, #F3F6FD 0%, #EDF3FC 100%);
  box-shadow: 2px 1px 13px 0px rgba(0,51,154,0.05), -5px -3px 26px 1px rgba(97,136,254,0.02);
  border-radius: 50%;
  border: 2px solid #FFFFFF;
  position: relative;
  padding: 16px;
}

.summary .circle-inside {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  font-size: 1.8125rem;
  font-weight: 500;
  color: #FFFFFF;
  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;
}

.circle-1 {
  background: linear-gradient(0deg, #5996FF 0%, #9DC0FF 100%);
}

.circle-2 {
  background: linear-gradient(0deg, #9CA3FF 0%, #B2B7FF 100%);
}

.circle-3 {
  background: linear-gradient(0deg, #FFFFFF 0%, #8BCDFF 0%, #B0DAFF 100%);
}

.circle-4 {
  background: linear-gradient(0deg, #5996FF 0%, #9DC0FF 100%);
}

.summary .circle-inside > p > span {
  font-size: 2.3125rem;
  color: #0046FA;
}



/* =========================================
   Media Queries (max-width: 480px)
========================================= */
@media (max-width: 480px) {
  .nav {
    width: 0;
    left: 20px;
  }

  .nav ul li span {
    visibility: hidden;
  }

  .product-intro .container {
    width: 85%;
    padding-bottom: 450px;
  }

  .product-intro-grid {
    flex-direction: row;
  }

  .card-row {
    flex: 1;
    flex-direction: column;
    align-items: center;
    row-gap: 30px;
  }

  .card-outline {
    width: 90%;
    height: 170px;
    padding: 10px;
    font-size: 1.3rem;
  }

  .arrow-icon {
    transform: rotate(90deg) scale(0.6);
    top: calc(50% - 22px);
    left: 28px;
  }

  .card-outline .white-card p {
    padding: 0 10px;
  }

  .card-outline .white-card img {
    width: 50px;
    height: 50px;
  }

  .arrow-icon.merge {
    top: 100%;
    left: 28px;
  }

  .card-outline-large {
    transform: scale(0.8);
    top: 98%;
    right: 24px;
  }

  .product-function-title > p {
    margin-top: 5px;
    padding: 0 10px;
  }

  .product-tabs {
    margin: 10px 50px 0;
    font-size: 1.3rem;
    flex-wrap: nowrap;
  }

  .product-tab-btn {
    padding: 10px 10px;
  }

  .product-function .product-tab-content {
    padding: 30px 50px;
    flex-direction: column;
    column-gap: 0;
  }

  .product-function .product-tab-content .card-list {
    flex-direction: row;
    flex-wrap: wrap;
    align-items: flex-start;
    gap: 0;
  }

  .product-function .product-tab-content .card-list li {
    width: 50%;
    padding: 0 10px 20px;
  }

  .product-function-card {
    width: auto;
    height: auto;
    padding: 15px 20px;
  }

  .product-function-card > h3 {
    margin-left: 0;
    padding: 0;
    border-left: none;
    font-size: 1.1rem;
    white-space: nowrap;
    text-align: center;
  }

  .product-function-card > p {
    display: none;
  }

  .product-img {
    max-width: 100%;
  }

  .product-img img {
    border-radius: 10px;
  }

  .summary {
    padding: 60px 0;
  }

  .summary .container {
    width: 85%;
    flex-wrap: wrap;
    align-items: flex-start;
    gap: 0;
  }

  .summary .container li {
    width: 50%;
    padding: 0 10px 20px;
  }

  .summary .circle-outline {
    width: 184px;
    height: 184px;
  }

  .summary .circle-inside {
    font-size: 1.2rem;
  }

  .summary .circle-inside > p > span {
    font-size: 1.55rem;
  }
}