*{
  margin: 0;
  border: 0;
  padding: 0;
}
.dark-theme{
  --background-primary: #212121; /*#191C20;*/
  --background-secondary: #87ceeb;
  --background-tertiary: #101416;
  --background-quad: #0F1416;
  --background-pent: #0F1416;
  --background-hover: #0F1416;
  --footer-background: #212121;
  --text-color: #87ceeb;
  --text-secondary: #e5e7eb;
  --svg: invert(100%) sepia(0%) saturate(7475%) hue-rotate(20deg) brightness(0%) contrast(111%);
  --text-primary: invert(100%) sepia(0%) saturate(7475%) hue-rotate(20deg) brightness(100%) contrast(111%);
  --logo-color: brightness(0) saturate(100%) invert(76%) sepia(44%) saturate(403%) hue-rotate(165deg) brightness(95%) contrast(94%);
  --nav-color: #0F1511;
  --primary-color: #F0faf1;
  --button-color: #212121;
  --box-shadow: rgba(99, 154, 239, 0.35) 0px 5px 15px;
  --border-color: #373737;
  --navbtns: #c4c4c4;
  --btn-bg: #212121;
  --btn-border: #353535;
  --cards: #212121;
}
.light-theme{
  --background-primary: #EBEDF1;
  --background-secondary: #3F5881;
  --background-tertiary: #f7f7f7;
  --background-quad: #f8f8f8;
  --background-pent: #FAFAFA;
  --background-hover: #F1F4F6;
  --footer-background: #E6E7EB;
  --svg: invert(100%) sepia(0%) saturate(7475%) hue-rotate(20deg) brightness(100%) contrast(111%);
  --text-color: #3f5881;
  --text-primary: invert(100%) sepia(0%) saturate(7475%) hue-rotate(20deg) brightness(0%) contrast(111%);
  --text-secondary: #6a7b8f;
  --logo-color: invert(30%) sepia(65%) saturate(376%) hue-rotate(179deg) brightness(93%) contrast(91%);
  --nav-color: #fafafa;
  --primary-color: #0F1511;
  --button-color: #FEFEFE;
  --box-shadow: rgba(63, 88, 129, 0.35) 0px 5px 15px;
  --border-color: #E8E9EB;
  --navbtns: #272727;
  --btn-bg: #ffffff;
  --cards: #fefefe;
}
.icon{
  filter: var(--logo-color);
}
html{
  font-size: 10px;
}
a,button{
  cursor: pointer;
}
h1{
  font-family: 'Open Sans', sans-serif;
  font-weight: 800;
}
body{
  background-color: var(--nav-color);
  font-family: 'Open Sans', sans-serif;
}
/* section-1 | nav-bar*/
.sec1{
  width: 100%;
}
.nav-bar{
  width: 100%;
  min-height: 80px;
  height: 100%;
  background: var(--nav-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.logo{
  display: flex;
  align-items: center;
}
.logo img{
  filter: var(--logo-color);
  width: 300px;
}
.nav-btns{
  display: flex;
  flex-direction: row-reverse;
  column-gap: 10px;
  margin-right: 10px;
}
.nav-btns button{
  font-size: 35px;
  width: 70px;
  height: 70px;
  background: var(--background-primary);
  border-radius: 50%;
  border: 1px solid var(--border-color);
  color: var(--navbtns);
  padding: 8px;
  text-align: center;
  display: flex;
  justify-content: center;
  align-items: center;
}

/* section-2 */
.sec-2{
  min-height: 44vh;
  height: 100%;
}
.sec-2-1{
  height: 100%;
  min-height: 44vh;
  padding: 3vh 0vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: var(--background-primary);
}
.sec-2-1>:nth-child(1){
  color: var(--text-color);
  font-size: 65px;
}
.sec-2-1>:nth-child(2){
  font-size: 80px;
  color: var(--primary-color);
  margin-bottom: 30px;
}
.about{
  width: 65%;
  font-size: 30px;
  text-align: center;
  line-height: 50px;
  font-weight: 500;
  color: var(--text-secondary);
}
/* section-3*/
.sec-3{
  background: var(--background-tertiary);
  min-height: 60vh;
  /*max-height: 235vh;*/
  height: 100%;
}
.sec-3-1{
  min-height: 60vh;
  height: 100%;
  /*max-height: 235vh;*/
  height: auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  
}
.sec-3-1-1 p{
  color: var(--text-secondary);
  font-size: 25px;
  text-align: center;
  margin-bottom: 30px;
}
.sec-3-1-1-1{
  display: flex;
  flex-direction: row;
  column-gap: 8px;
  font-size: 35px;
  margin-top: 50px;
  justify-content: center;
}
.sec-3-1-1-1>:nth-child(1){
  color: var(--primary-color);
}
.sec-3-1-1-1>:nth-child(2){
  color: var(--text-color);
  
}
.sec-3-1-2, #classesList{
  display: grid;
  grid-template-columns: auto auto;
  column-gap: 30px;
  row-gap: 20px;
}
.class-btn{
  border: 1px solid var(--border-color);
  padding: 60px 160px;
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background: var(--cards);
  row-gap: 5px;
  transition: transform 0.3s ease;
}
.class-btn:hover, #class-btn:hover{
  border: 1px solid var(--text-color);
  box-shadow: var(--box-shadow);
  transform: scale(1.1, 1.1);
  
}
.class-btn>:nth-child(1),#class-btn>:nth-child(1){
  color: var(--text-color);
  font-size: 30px;
  
}
.class-btn a>:nth-child(1),#class-btn a>:nth-child(1){
  color: var(--text-color);
  font-size: 30px;
  text-align: center;
  
}
.class-btn a, #class-btn a{
  text-decoration: none;
  text-align: center;
}
.class-btn>:nth-child(2), #class-btn>:nth-child(2){
  color: var(--primary-color);
  text-wrap: nowrap;
  font-size: 25px;
  
}
.class-btn a>:nth-child(2), #class-btn a>:nth-child(2){
  color: var(--primary-color);
  text-wrap: nowrap;
  font-size: 25px;
  text-align: center;
}
/* section-4*/
.sec-4{
  background: var(--background-quad);
  min-height: 60vh;
  height: 100%;
}
.sec-4-1{
  min-height: 60vh;
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: start;
  
}
.sec-4-1-1 p{
  color: var(--text-secondary);
  font-size: 25px;
  text-align: center;
  margin-bottom: 30px;
}
.sec-4-1-1-1{
  display: flex;
  flex-direction: row;
  column-gap: 8px;
  font-size: 38px;
  margin-top: 50px;
  justify-content: center;
}
.sec-4-1-1-1>:nth-child(1){
  color: var(--primary-color);
}
.sec-4-1-1-1>:nth-child(2){
  color: var(--text-color);
}
.sec-4-1-2{
  display: grid;
  grid-template-columns: auto auto;
  column-gap: 30px;
  row-gap: 20px;
}
.about-btn{
  border: 1px solid var(--border-color);
  padding: 50px;
  padding-left: 50px;
  padding-right: 50px;
  border-radius: 9px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background: var(--button-color);
  row-gap: 5px;
}
.about-btn:hover{
  border: 1px solid var(--text-color);
  background: var(--background-hover);
  box-shadow: var(--box-shadow);
}
.about-btn:hover span{
  box-shadow: var(--box-shadow);
  border-radius: 10px;
}
.about-btn:hover h1{
  color: var(--text-color);
  
}
.about-btn>:nth-child(1){
  color: var(--text-color);
  font-size: 50px;
  filter: var(--logo-color);
  display: flex;
  align-items: center;
}
.about-btn>:nth-child(2){
  color: var(--primary-color);
  text-wrap: nowrap;
  font-size: 25px;
}
.about-btn>:nth-child(3){
  color: var(--text-secondary);
  font-size: 14px;
  text-align: center;
  line-height: 25px;
  font-weight: 400;
}

/* section-5 --footer---*/
.sec-5{
  background: var(--footer-background);
  min-height: 40vh;
  height: auto;
}

.footer-abt{
  width: 90%;
  font-size: 10px;
  margin-left: 30px;
  margin-top: -10px;
  line-height: 15px;
  font-weight: 500;
  color: var(--text-secondary);
}
.sec-5-1-1-1 p img{
  width: 10px;
  margin-left: 30px;
  filter: var(--logo-color);
  margin-top: px;
}

.sec-5-1-1-1 p{
  font-size: 10px;
  font-weight: 500;
  color: var(--text-secondary);
  margin-top: 5px;
}
.sec-5-1-1{
  display: flex;
}
.sec-5-1-1-1{
  display: flex;
  flex-direction: column;
  width: 50%;
}
.sec-5-1-1-2{
  display: flex;
  column-gap: 80px;
}
.sec-5-1-1-2 h1{
  color: var(--primary-color);
  margin-top: 30px;
  margin-left: 40px;
  margin-bottom: 10px;
}
.sec-5-1-1-2 ul{
  color: var(--text-secondary);
  list-style: none;
  margin-left: 40px;
  font-weight: 500;
  font-size: 10px;
  line-height: 15px;
}
.sec-5-1-1-2 ul a{
  color: var(--text-secondary);
  text-decoration: none;
}
.svg{
  width: 10px;
  height: 10px;
  filter: var(--logo-color);
}
.sec-5-1-2 h1{
  color: var(--text-color);
  margin-left: 30px;
}
.sec-5-1-2 p{
  margin-left: 30px;
  color: var(--text-secondary);
}
.sec-5-1-2 u{
  color: var(--text-color);
}
.social-btns{
  display: flex;
  margin-left: 30px;
  margin-top: 10px;
  margin-bottom: 10px;
  column-gap: 20px;
}
.social-btns button{
  padding: 15px;
  border-radius: 10px;
  border: 2px solid var(--border-color);
  display: flex;
  align-items: center;
  transition: transform 0.3s ease;
}
.social-btns button:hover{
  transform: scale(1.2, 1.2);
}
.social-btns button a{
  color: #fff;
  text-decoration: none;
}
.social-btns>:nth-child(1){
  background: linear-gradient(45deg,
    #405de6,
    #5851db,
    #833ab4,
    #c13584,
    #e1306c,
    #fd1d1d);
  color: #fff;
  font-weight: 800;
}
.social-btns>:nth-child(2){
  background: linear-gradient(to bottom, #3F8DCF, #1C53B7);
  color: #fff;
  font-weight: 800;
}
.social-btns>:nth-child(3){
  background-color: rgb(255, 0, 0);
  color: #fff;
  font-weight: 800;
}
.social-btns>:nth-child(4){
  background-color: #000;
  color: #fff;
  font-weight: 800;
}
.social-btns button a img{
  width: 15px;
  margin-right: 5px;
  margin-bottom: -3px;
  filter: invert(100%) sepia(0%) saturate(7475%) hue-rotate(20deg) brightness(100%) contrast(111%);
}
.sec-5-2{
  display: flex;
}
.sec-5-2 p{
  display: flex;
  align-items: end;
  margin-left: 30px;
  color: var(--text-secondary);
}
.sec-5-2 p img {
  width: 15px;
  margin-right: 10px;
  margin-top: -8px;
  filter: var(--logo-color);
  text-shadow: var(--box-shadow);
}

.part-1 {
  background: var(--background-pent);
  min-height: 100vh; /* ensures it fills screen at least once */
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start; /* start at top, not center */
  padding: 5rem 0; /* add breathing space */
  overflow: hidden;
  height: 100%;
}
.part-1-1 {
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 3rem; /* space between inner sections */
}
.part-1-1-1-1{
  display: flex;
  flex-direction: row;
  column-gap: 8px;
  font-size: 35px;
  margin-top: 50px;
  justify-content: center;
  margin-bottom: 30px;
}
.part-1-1-1-1>:nth-child(1){
  color: var(--primary-color);
}
.part-1-1-1-1>:nth-child(2){
  color: var(--text-color);
}
.part-1-1-2{
  display: grid;
  grid-template-columns: auto auto;
  column-gap: 30px;
  row-gap: 20px;
}
.subject-btn{
  border: 1px solid var(--border-color);
  width: 420px;
  height: 180px;
  /*padding: 60px 140px;*/
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background: var(--cards);
  row-gap: 5px;
  transition: transform 0.3s ease;
}
.subject-btn:hover{
  border: 1px solid var(--text-color);
  box-shadow: var(--box-shadow);
  transform: scale(1.1, 1.1);
}
.subject-btn>:nth-child(1){
  color: var(--text-color);
  font-size: 25px;
  text-wrap: nowrap;
}
.subject-btn>:nth-child(2){
  color: var(--primary-color);
  text-wrap: nowrap;
  font-size: 20px;
}

.subject-btn a>:nth-child(1){
  color: var(--text-color);
  font-size: 25px;
  text-align: center;
  text-wrap: nowrap;
}
.subject-btn a{
  text-decoration: none;
  text-align: center;
  text-wrap: nowrap;
}
.subject-btn a>:nth-child(2){
  color: var(--primary-color);
  text-wrap: nowrap;
  font-size: 20px;
  text-align: center;
  text-wrap: nowrap;
}
/*--------upload----------*/
.card{
      width: 90%;
      max-width: 820px;
      margin:40px auto;
      padding:22px;
      border-radius:16px;
      background: var(--background-quad);
      color: var(--text-color);
      box-shadow:0 8px 30px rgba(0,0,0,0.06);
      text-align:center;
    }
    .card h1{
      font-weight: 800;
      margin-bottom:6px;
    }
    .card p.hint { margin-top:0; color: var(--text-secondary); font-size:16px; margin-bottom:14px; }

    .box{ height: 38vh; display:flex; align-items:center; justify-content:center; }

    .upload-inside{ display:flex; flex-direction:column; gap:8px; align-items:center; justify-content:center; }

    .upload-box{
      cursor: pointer;
    }
    .upload-box .material-symbols-outlined{
      font-size:48px;
      min-width: 42vh;
      min-height: 30vh;
      border:2px dashed var(--text-color);
      background: var(--background-primary);
      color:  var(--background-secondary);
      border-radius: 16px;
      display: flex;
      justify-content: center;
      align-items: center;
      padding: 20px;
      box-sizing: border-box;
    }
    .upload-box:hover .material-symbols-outlined{
      background: var(--background-tertiary);
      transform: translateY(-2px);
      transition: all 180ms ease;
    }

    /* File List (pending selection) */
    .file-list{
      margin-top:18px;
      text-align:left;
    }
    .file-item{
      background: var(--background-tertiary);
      padding: 12px;
      border-radius: 12px;
      margin-bottom: 10px;
      display: flex;
      justify-content: space-between;
      align-items: center;
      animation: fadeIn 0.2s ease;
    }

    .filename{
      overflow: hidden;
      white-space: nowrap;
      text-overflow: ellipsis;
      max-width: 60%;
      font-size: 14px;
    }

    .delete-btn{
      background: var(--background-secondary);
      border:0;
      color: white;
      width:34px;
      height:34px;
      border-radius:50%;
      cursor:pointer;
      display:flex;
      align-items:center;
      justify-content:center;
    }

    #uploadBtn{
      margin-top:16px;
      width:100%;
      padding:10px;
      border:0;
      background: var(--background-secondary);
      color: white;
      border-radius:10px;
      cursor:pointer;
      font-size:15px;
      font-weight: 700;
    }
    #uploadBtn:disabled{
      opacity:0.5;
      cursor: not-allowed;
    }

    /* Uploaded files list (history) */
    #uploadedSection { margin-top: 18px; text-align:left; display:block; }
    #filesList{ list-style:none; padding-left:0; margin:0; }
    #filesList li { display:flex; justify-content:space-between; gap:8px; align-items:center; padding:8px 10px; border-radius:8px; background:var(--background-primary); margin-bottom:8px; box-shadow: 0 2px 8px rgba(2,6,23,0.03); font-size:14px; }
    #filesList .btn { text-decoration:none; padding:6px 8px; border-radius:8px; border: 1px solid #e6e9ef; font-size:13px; color: var(--text-color); font-weight: 600;}

    #status { margin-top:10px; font-size:15px; color: var(--text-secondary); min-height:18px; text-align:center; }

    /* --- Thank You Popup --- */
    #thankyouPopup {
      position: fixed;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%) scale(0.85);
      background: linear-gradient(180deg, rgba(255,255,255,0.98), rgba(250,250,255,0.98));
      padding: 18px 22px;
      border-radius: 12px;
      box-shadow: 0 18px 50px rgba(15,23,42,0.18);
      font-size: 15px;
      color: #0f172a;
      text-align: center;
      z-index: 9999;
      opacity: 0;
      transition: transform 320ms cubic-bezier(.2,.9,.28,1), opacity 320ms ease;
      pointer-events: none;
      min-width: 260px;
      display: flex;
      gap: 12px;
      align-items: center;
    }
    #thankyouPopup.show {
      opacity: 1;
      transform: translate(-50%, -50%) scale(1);
      pointer-events: auto;
    }
    #thankyouPopup .icon {
      width: 44px;
      height: 44px;
      border-radius: 50%;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      background: linear-gradient(135deg,#34d399,#10b981);
      box-shadow: 0 6px 20px rgba(16,185,129,0.18);
      flex: 0 0 44px;
    }
    #thankyouPopup .icon svg{width:22px;height:22px;fill:white}
    #thankyouPopup .content {text-align:left}
    #thankyouPopup .title {font-weight:600; font-size:15px; margin-bottom:2px}
    #thankyouPopup .subtitle {font-size:13px;color:#475569}

    @keyframes fadeIn {
      from {opacity:0; transform: translateY(4px);}
      to   {opacity:1; transform: translateY(0);}
    }

.skeleton-card {
  background: var(--cards);
  border-radius: 8px;
  padding: 15px;
  width: 420px;
  height: 180px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  margin-bottom: 15px;
  overflow: hidden;
  position: relative;
}

.skeleton-line {
  height: 14px;
  background: var(--text-color);
  margin-bottom: 10px;
  border-radius: 4px;
}

.skeleton-line.short {
  width: 50%;
}

.skeleton-line.medium {
  width: 75%;
}

.shimmer {
  position: absolute;
  top: 0;
  left: -150px;
  height: 100%;
  width: 150px;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255,255,255,0.1),
    transparent
  );
  animation: shimmer 1.2s infinite;
}

@keyframes shimmer {
  0% { left: -150px; }
  100% { left: 100%; }
}

@media (max-width:420px){
      .card{padding:12px}
      .upload-box .material-symbols-outlined{ min-width: 270px; min-height: 180px; font-size:40px }
      #thankyouPopup{min-width:200px;padding:14px}
      #thankyouPopup .icon{width:40px;height:40px}
      }
@media(max-width: 1024px){
  .sec-2{
    min-height: 44vh;
    height: 100%;
  }
  .sec-2-1{
    min-height: 44vh;
    height: 100%;
  }
  .sec-3, .sec-3-1{
    min-height: 80vh;
    height: 100%;
  }
  .sec-4{
    background: var(--background-quad);
    min-height: 70vh;
    height: 100%;
  }
  .sec-4-1{
    min-height: 70vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
  }
    .sec-5 {
      min-height: 25vh;
      height: 100%;
  }
  .sec-5 .sec-5-2{
    background: var(--footer-background);
    height: auto;
    width: 100%;
  }
  
/*classes*/
/*.part-1{
  background: var(--background-tertiary);
  height: 90vh;
}
.part-1-1{
  height: 90vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: var(--background-pent);
  
}*/
.part-1 {
  background: var(--background-pent);
  min-height: 100vh; /* ensures it fills screen at least once */
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start; /* start at top, not center */
  padding: 5rem 0; /* add breathing space */
  overflow: hidden;
  height: 100%;
}

.part-1-1 {
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 3rem; /* space between inner sections */
}

.part-1-1-1-1{
  display: flex;
  flex-direction: row;
  column-gap: 8px;
  font-size: 35px;
  margin-top: 50px;
  justify-content: center;
  margin-bottom: 30px;
}
.part-1-1-1-1>:nth-child(1){
  color: var(--primary-color);
}
.part-1-1-1-1>:nth-child(2){
  color: var(--text-color);
}
.part-1-1-2{
  display: grid;
  grid-template-columns: auto auto;
  column-gap: 30px;
  row-gap: 20px;
}
.subject-btn{
  border: 1px solid var(--border-color);
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background: var(--cards);
  row-gap: 5px;
  transition: transform 0.3s ease;
}
.subject-btn:hover{
  border: 1px solid var(--text-color);
  box-shadow: var(--box-shadow);
  transform: scale(1.1, 1.1);
}
.subject-btn>:nth-child(1){
  color: var(--text-color);
  font-size: 25px;
  text-wrap: nowrap;
}
.subject-btn>:nth-child(2){
  color: var(--primary-color);
  text-wrap: nowrap;
  font-size: 20px;
}

.subject-btn a>:nth-child(1){
  color: var(--text-color);
  font-size: 25px;
  text-align: center;
  text-wrap: nowrap;
}
.subject-btn a{
  text-decoration: none;
  text-align: center;
  text-wrap: nowrap;
}
.subject-btn a>:nth-child(2){
  color: var(--primary-color);
  text-wrap: nowrap;
  font-size: 20px;
  text-align: center;
  text-wrap: nowrap;
  }
  /* -------------view.html-------*/
iframe {
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
  width: 100%;
  aspect-ratio: 1 / 1.414;
  border: 2px solid var(--border-color);
  border-radius: 12px;
  background: var(--background-tertiary);
  overflow-x: hidden;
}
.iframe-mid{
  display: flex;
  justify-content: center;
  height: 100%;
  max-height: 80vh;
  padding: 50px 0 300px 0;
  overflow: hideen;
}
.iframe-container {
  width: 90%;
  height: 100%;
  max-width: 900px;
  max-height: 300vh;
  /* Adjust as needed */
  aspect-ratio: 1 / 1.414; /* Standard A4 paper ratio */
  margin: 0 0;
  overflow: hidden;
}
.iframe-container iframe {
  width: 100%;
  height: 100%;
  height: 80vh;
  border: 2px solid var(--border-color);
  background: var(--background-primary);
  overflow: hidden;
}

.v-btns{
  display: flex;
  justify-content: space-between;
  margin: 5px 15px;
}
.left button,.right button{
  font-weight: 800;
  padding: 10px 20px;
  background: var(--background-primary);
  color: var(--background-tertiary);
  border: 1px solid var(--text-secondary);
  border-radius: 5px;
  cursor: pointer;
}
.right .spl{
  color: var(--text-color);
  background: var(--background-tertiary);
  margin: 0px 5px;
  
}

#shareBtn:hover {
  opacity: 0.8;
}
#download button:hover{
  background: var(--text-color);
}
#download button:hover img{
  filter: var(--svg);
}
.norm img{
  filter: var(--text-primary);
}
.right .spl img{
  font-weight: 800;
  filter: var(--logo-color);
  }
}
@media(max-width: 767px){
  .nav-bar {
    width: 100%;
    min-height: 40px;
    background: var(--nav-color);
    display: flex;
    justify-content: space-between;
    align-content: center;
  }
  .logo img{
    filter: var(--logo-color);
    width: 150px;
  }
  .nav-btns button{
  font-size: 20px;
  width: 40px;
  height: 40px;
  top: 0;
  right: 0;
  padding: 10px;
  }
  .nav-btns
  .sec-2{
    min-height: 100vh;
    height: 100%;
  }
  .sec-2-1{
    min-height: 100vh;
    height: 100%;
    padding: 4vh 0vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    line-height: 1.1;
}
.sec-2-1>:nth-child(1){
  color: var(--text-color);
  font-size: 28px;
  text-shadow: var(--box-shadow);
  font-weight: 800;
}
.sec-2-1>:nth-child(2){
  font-size: 30px;
  color: var(--primary-color);
  margin-bottom: 25px;
  font-weight: 800;
}
.about{
  width: 85%;
  font-size: 18px;
  text-align: center;
  line-height: 40px;
  font-weight: 500;
  color: var(--text-secondary);
  }
  .sec-3{
  background: var(--background-tertiary);
  min-height: 295vh;
  height: 100%;
  }
  .sec-3-1{
    min-height: 295vh;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: start;
  }
  .sec-3-1-1 p{
    color: var(--text-secondary);
    font-size: 15px;
    text-align: center;
    margin-bottom: 30px;
  }
  .sec-3-1-1-1{
    display: flex;
    flex-direction: column;
    column-gap: 8px;
    font-size: 25px;
    margin-top: 50px;
    text-align: center;
    line-height: 50px;
  }
  .sec-3-1-1-1>:nth-child(1){
    color: var(--primary-color);
    font-size: 35px;
  }
  .sec-3-1-1-1>:nth-child(2){
    color: var(--text-color);
    font-size: 35px;
  }
  .sec-3-1-2, #classesList{
    display: grid;
    grid-template-columns: auto;
    column-gap: 30px;
    row-gap: 20px;
  }
  .class-btn{
    border: 1px solid var(--border-color);
    padding: 50px 60px;
    border-radius: 10px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background: var(--cards);
    row-gap: 5px;
    transition: transform 0.3s ease;
  }
  .sec-4, .sec-4-1{
    min-height: 140vh;
    height: 100%;
  }
  .sec-4-1-1 p{
    margin-top: 10px;
    font-size: 15px;
    text-align: center;
  }
  .sec-4-1-1-1{
    flex-direction: column;
    font-size: 20px;
    margin-top: 40px;
    justify-content: center;
    text-align: center;
  }
  .sec-4-1-1-1>:nth-child(1){
    color: var(--primary-color);
    font-size: 35px;
  }
  .sec-4-1-1-1>:nth-child(2){
    color: var(--text-color);
    font-size: 35px;
  }
  .sec-4-1-2{
    display: grid;
    grid-template-columns: auto;
    column-gap: 30px;
    row-gap: 20px;
  }
  .about-btn{
    width: 300px;
    height: 150px;
    padding: 30px 10px;
  }
  .about-btn:hover{
    border: 1px solid var(--text-color);
    background: var(--background-hover);
    box-shadow: var(--box-shadow);
  }
  .about-btn:hover span{
    box-shadow: var(--box-shadow);
    border-radius: 10px;
  }
  .about-btn:hover h1{
    color: var(--text-color);
  }
  .about-btn>:nth-child(1){
    color: var(--text-color);
    filter: var(--logo-color);
    width: 20px;
    height: 20px;
  }
  .about-btn>:nth-child(2){
    font-size: 20px;
  }
  .about-btn>:nth-child(3){
    color: var(--text-secondary);
    font-size: 12px;
    line-height: 25px;
    
  }
  .sec-5{
   /* min-height: 109.5vh;*/
    min-height: 100vh;
    height: auto;
  }
  .footer-abt{
    width: 85%;
    font-size: 10px;
    margin-left: 30px;
    margin-top: -10px;
    line-height: 15px;
    font-weight: 500;
    color: var(--text-secondary);
  }
  .sec-5-1-1-1 p img{
    width: 10px;
    margin-left: 30px;
    filter: var(--logo-color);
    margin-top: px;
  }
  .sec-5-1-1-1 p{
    font-size: 15px;
    font-weight: 500;
    color: var(--text-secondary);
    margin-top: 3px;
    line-height: 30px;
  }
  .sec-5-1-1{
    display: flex;
    flex-direction: column;
  }
  .sec-5-1-1-1{
    display: flex;
    flex-direction: column;
    width: 100%;
  }
  .sec-5-1-1-2{
    display: flex;
    flex-direction: column;
    column-gap: 80px;
  }
  .sec-5-1-1-2 h1{
    color: var(--primary-color);
    margin-top: 25px;
    margin-left: 40px;
    margin-bottom: 10px;
  }
  .sec-5-1-1-2 ul{
    color: var(--text-secondary);
    list-style: none;
    margin-left: 40px;
    font-weight: 500;
    font-size: 10px;
    line-height: 15px;
  }
  .sec-5-1-1-2 ul a{
    color: var(--text-secondary);
    text-decoration: none;
  }
  .sec-5-1-2 h1{
    color: var(--text-color);
    margin-left: 30px;
    margin-top: 20px;
  }
  .sec-5-1-2 p{
    margin-left: 30px;
    color: var(--text-secondary);
  }
  .sec-5-1-2 u{
    color: var(--text-color);
  }
  .social-btns{
    display: flex;
    margin-left: 24px;
    margin-top: 10px;
    margin-bottom: 10px;
    column-gap: 10px;
  }
  .social-btns button{
    padding: 3px;
    padding-left: 10px;
    padding-right: 10px;
    border-radius: 10px;
    border: 2px solid var(--border-color);
    display: flex;
    flex-direction: row;
    align-items: center;
    transition: transform 0.3s ease;
  }
  .social-btns button:hover{
    transform: scale(1.2, 1.2);
  }
  .social-btns button a{
    color: #fff;
    text-decoration: none;
  }
  .social-btns>:nth-child(1){
    background: linear-gradient(45deg,
      #405de6,
      #5851db,
      #833ab4,
      #c13584,
      #e1306c,
      #fd1d1d);
    color: #fff;
    font-weight: 800;
  }
  .social-btns>:nth-child(2){
    background: linear-gradient(to bottom, #3F8DCF, #1C53B7);
    color: #fff;
    font-weight: 800;
  }
  .social-btns>:nth-child(3){
    background-color: rgb(255, 0, 0);
    color: #fff;
    font-weight: 800;
  }
  .social-btns>:nth-child(4){
    background-color: #000;
    color: #fff;
    font-weight: 800;
  }
  .social-btns button a img{
    width: 15px;
    margin-right: 3px;
    margin-bottom: -3px;
    filter: invert(100%) sepia(0%) saturate(7475%) hue-rotate(20deg) brightness(100%) contrast(111%);
  }
  .sec-5-2{
    display: flex;
  }
  .sec-5-2 p{
    display: flex;
    align-items: end;
    margin-left: 30px;
    color: var(--text-secondary);
    font-size: 13px;
  }
  .sec-5-2 p img {
    width: 15px;
    margin-right: 10px;
    margin-top: -8px;
    filter: var(--logo-color);
    text-shadow: var(--box-shadow);
  }
  /*subjects*/
  .part-1{
    background: var(--background-pent);
    min-height: 70vh;
    height: 100%;
  }
  .part-1-1{
    min-height: 70vh;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: start;
    background: var(--background-pent);
  }
  .part-1-1-1 p{
    color: var(--text-secondary);
    font-size: 15px;
    text-align: center;
    margin-bottom: 30px;
  }
  .part-1-1-1-1{
    display: flex;
    flex-direction: row;
    column-gap: 8px;
    font-size: 25px;
    margin-top: 50px;
    text-align: center;
    line-height: 50px;
  }
  .part-1-1-1-1>:nth-child(1){
    color: var(--primary-color);
    transition: transform 0.3s ease;
  }
  .part-1-1-2{
    grid-template-columns: auto ;
    }
  .subject-btn{
    width: 250px;
    height: 120px;
    padding: 20px;
  }
  .subject-btn a>:nth-child(1){
    font-size: 20px;
  }
   /* -------------view.html-------*/
  .iframe-container{
    padding: 10px;
    overflow: hidden;
  }
  .iframe-mid{
    margin: 20px 0 90px 0;
    padding: 50px 0;
    overflow: hidden;
  }
  .v-btns{
    margin-top: 15px;
    
  }
.left button,.right button{
  padding: 4px 8px;
  margin-left: 5px;
}

.norm img{
  height: 18px;
  width: 18px;
}
.right .spl img{
  height: 18px;
  width: 18px;
}
}
@media(min-width: 992px){
  .part-1-1,
  .part-1,
  .sec-3,
  .sec-3-1
  {
    min-height: 225vh;
    height: 100%;
  }
  .sec-2-1{
    min-height: 185vh;
    height: 100%;
  }
  .sec-4,
  .sec-4-1{
    min-height: 150vh;
    height: 100%;
   }
  .sec-5{
    min-height: 62vh;
    height: 100%;
  }
  .iframe-container,.iframe{
    min-height: 500vh;
    height: 100%;
    aspect-ratio: 1.414/1;
  }
  .iframe-mid{
    max-height: 900vh;
    height: 100%;
  }
}
@media(min-width: 1200px){
  .part-1-1,
  .part-1,
  .sec-3,
  .sec-3-1{
    min-height: 225vh;
    height: 100%;
  }
  .sec-2-1{
    min-height: 185vh;
    height: 100%;
  }
  .sec-4,
  .sec-4-1{
    min-height: 150vh;
    height: 100%;
  }
  .sec-5{
    min-height: 62vh;
    height: 100%;
  }
   .iframe-container,.iframe{
    min-height: 200vh;
    aspect-ratio: 1.414/1;
  }
  .iframe-mid{
    max-height: 500vh;
    
  }
}