html, body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  overflow-x: hidden;
  font-family: Arial, sans-serif;
  background: black;
  color: white;
}

/* RULER BORDER */
.ruler-frame {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 3;
  pointer-events: none;

  box-shadow: inset 0 0 0 12px rgba(0, 0, 0, 0.85);

  background-image:
    repeating-linear-gradient(
      0deg,
      rgba(255,255,255,0.14) 0px,
      rgba(255,255,255,0.14) 1px,
      transparent 1px,
      transparent 20px
    ),
    repeating-linear-gradient(
      90deg,
      rgba(255,255,255,0.1) 0px,
      rgba(255,255,255,0.1) 1px,
      transparent 1px,
      transparent 20px
    );
}

/* COLOR BACKGROUND */
.background {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;

  background:
    radial-gradient(circle at 30% 30%, red, transparent 40%),
    radial-gradient(circle at 70% 40%, orange, transparent 45%),
    radial-gradient(circle at 50% 80%, yellow, transparent 50%),
    radial-gradient(circle at 20% 70%, orangered, transparent 45%);

  animation: colorShift 10s linear infinite;
}

@keyframes colorShift {
  0%   { filter: hue-rotate(0deg) brightness(1); }
  25%  { filter: hue-rotate(90deg) brightness(1.1); }
  50%  { filter: hue-rotate(180deg) brightness(1.2); }
  75%  { filter: hue-rotate(270deg) brightness(1.1); }
  100% { filter: hue-rotate(360deg) brightness(1); }
}

/* MAIN CENTER CONTENT */
.container {
  position: relative;
  z-index: 2;

  height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;

  text-align: center;
}

/* TITLE + ORBIT */
.title-orbit-wrapper {
  position: relative;
  display: inline-block;
  margin-bottom: 50px;
}

.title-orbit-wrapper h1 {
  position: relative;
  z-index: 2;
  margin: 0;

  font-size: 52px;
  letter-spacing: 1px;

  color: white;

  text-shadow:
    0 0 8px black,
    0 0 16px black,
    0 0 25px rgba(255,255,255,0.9);
}

/* ORBIT AREA */
.orbit-container {
  position: absolute;
  top: 50%;
  left: 50%;

  width: 360px;
  height: 360px;

  transform: translate(-50%, -50%);
  pointer-events: none;
}

.orbit {
  position: absolute;
  width: 100%;
  height: 100%;
  border-radius: 50%;
}

.orbit span {
  position: absolute;
  top: 50%;
  left: 50%;

  font-size: 26px;
  color: rgba(255,255,255,0.75);
  text-shadow: 0 0 12px rgba(255,255,255,0.8);
}

/* SYMBOL PLACEMENT */
.orbit span:nth-child(1) {
  transform: rotate(0deg) translateX(175px);
}

.orbit span:nth-child(2) {
  transform: rotate(90deg) translateX(175px);
}

.orbit span:nth-child(3) {
  transform: rotate(180deg) translateX(175px);
}

.orbit span:nth-child(4) {
  transform: rotate(270deg) translateX(175px);
}

/* ORBIT ANIMATION */
.orbit1 {
  animation: spin 14s linear infinite;
}

.orbit2 {
  animation: spinReverse 20s linear infinite;
}

@keyframes spin {
  from { transform: rotate(0deg); }
  to   { transform: rotate(360deg); }
}

@keyframes spinReverse {
  from { transform: rotate(360deg); }
  to   { transform: rotate(0deg); }
}

/* COURSES BUTTON */
button {
  padding: 14px 32px;
  font-size: 19px;
  border: none;
  border-radius: 10px;
  cursor: pointer;

  background: white;
  color: black;

  box-shadow: 0 0 18px rgba(255,255,255,0.45);
  transition: transform 0.2s, box-shadow 0.2s;
}

button:hover {
  transform: scale(1.07);
  box-shadow: 0 0 28px rgba(255,255,255,0.85);
}

/* COURSES PAGE */
.courses-container {
  position: relative;
  z-index: 2;
  min-height: 100vh;
  padding: 60px 40px;
  text-align: center;
}

.courses-title {
  font-size: 52px;
  margin-bottom: 40px;
  text-shadow: 0 0 18px rgba(255,255,255,0.7);
}

.course-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 25px;
  max-width: 1100px;
  margin: 0 auto;
}

.course-card {
  background: rgba(0, 0, 0, 0.55);
  border: 1px solid rgba(255,255,255,0.25);
  border-radius: 18px;
  padding: 30px 20px;
  box-shadow: 0 0 20px rgba(255,255,255,0.18);
  backdrop-filter: blur(8px);
  transition: transform 0.25s, box-shadow 0.25s;
}

.course-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 0 32px rgba(255,255,255,0.45);
}

.course-card h2 {
  font-size: 26px;
  margin-bottom: 12px;
}

.course-card p {
  font-size: 17px;
  margin-bottom: 25px;
  color: rgba(255,255,255,0.85);
}

.course-card button,
.back-button {
  padding: 12px 24px;
  font-size: 16px;
}

.back-link {
  display: inline-block;
  margin-top: 40px;
  text-decoration: none;
}

/* RESPONSIVE */
@media (max-width: 900px) {
  .course-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 600px) {
  .course-grid {
    grid-template-columns: 1fr;
  }

  .courses-title {
    font-size: 40px;
  }
}

.course-page {
  position: relative;
  z-index: 2;
  min-height: 100vh;

  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;

  text-align: center;
  padding: 30px;
}

.course-page h1 {
  font-size: 50px;
  margin-bottom: 20px;
  text-shadow: 0 0 18px rgba(255,255,255,0.7);
}

.coming-text {
  font-size: 20px;
  margin-bottom: 30px;
  color: rgba(255,255,255,0.85);
}

.tabs {
  margin: 20px 0;
}

.tabs button {
  margin: 5px;
}

.tab-content {
  margin-top: 20px;
}

.lesson-content {
  max-width: 800px;
  margin: 0 auto;
  text-align: left;
}

.lesson-content ul {
  padding-left: 20px;
}

.lesson-content li {
  margin-bottom: 6px;
}

.tabs button.active {
  background: white;
  color: black;
}

.problems-layout {
  display: flex;
  justify-content: center;
  align-items: flex-start; /* 🔥 THIS is the key fix */
  gap: 40px;
}

.back-button {
  margin-top: 40px; /* increase this if you want more space */
}

.quiz-question {
  margin-bottom: 20px;
  padding: 15px;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.08);
}

.answer-choice {
  display: block;
  margin: 6px 0;
}

/* Check button stays centered */
#check-answer-btn {
  display: block;
  margin: 20px auto;
  padding: 10px 18px;
  border: none;
  border-radius: 8px;
  cursor: pointer;
}

/* Back + Next stay together centered */
.quiz-nav-buttons {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 35px;
  margin-top: 10px;
}

#back-btn,
#next-btn {
  padding: 10px 18px;
  border: none;
  border-radius: 8px;
  cursor: pointer;
}

/* answer colors */
.correct-answer {
  background: rgba(0, 255, 0, 0.25);
  border: 2px solid limegreen;
}

.wrong-answer {
  background: rgba(255, 0, 0, 0.25);
  border: 2px solid red;
}

.journey-link {
  display: inline-block;
  margin-top: 8px;
}

#submit-btn {
  padding: 10px 18px;
  border: none;
  border-radius: 8px;
  cursor: pointer;
}

.quiz-warning {
  max-width: 700px;
  margin: 15px auto 0 auto;
  padding: 12px 16px;

  background: rgba(255, 165, 0, 0.12);
  border: 1px solid rgba(255, 165, 0, 0.5);
  border-radius: 10px;

  color: rgba(255,255,255,0.9);
  font-size: 15px;
  line-height: 1.5;
  text-align: center;

  box-shadow: 0 0 12px rgba(255,165,0,0.2);
}

/* CONFETTI */
.confetti {
  position: fixed;
  top: -20px;

  width: 12px;
  height: 12px;

  opacity: 0.9;
  z-index: 9999;

  animation-name: confettiFall;
  animation-timing-function: linear;
  animation-fill-mode: forwards;
}

@keyframes confettiFall {

  0% {
    transform: translateY(0) rotate(0deg);
    opacity: 1;
  }

  100% {
    transform: translateY(120vh) rotate(1080deg);
    opacity: 0;
  }
}

.reviews-link {
  display: inline-block;
  margin-top: 8px;
}

.review-form {
  display: flex;
  flex-direction: column;
  gap: 14px;
  max-width: 700px;
  margin: 0 auto;
}

.review-form label {
  font-weight: bold;
}

.review-form input,
.review-form select,
.review-form textarea {
  padding: 12px;
  border-radius: 8px;
  border: none;
  font-size: 16px;
}

.review-form textarea {
  min-height: 120px;
  resize: vertical;
}

.donate-link {
  display: inline-block;
  margin-top: 8px;
}

/* GLASS CONTENT PANELS */
.lesson-content,
.quiz-question,
.formula-sheet,
#real .lesson-content,
#video,
#quiz-panel {
  background: linear-gradient(
    to bottom right,
    rgba(40, 40, 40, 0.78),
    rgba(15, 15, 15, 0.72)
  );

  border: 1px solid rgba(255,255,255,0.15);

  backdrop-filter: blur(10px);

  border-radius: 18px;

  padding: 28px;

  box-shadow:
    0 0 20px rgba(0,0,0,0.45),
    0 0 10px rgba(255,255,255,0.08);
}

.lesson-content,
.formula-sheet,
.quiz-question {
  margin-top: 20px;
}

.journey-tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    justify-content: center;
    max-width: 1000px;
    margin: 25px auto;
}

.video-container {
    display: flex;
    justify-content: center;
    margin-top: 20px;
}

.video-container iframe {
    max-width: 100%;
    border-radius: 12px;
    box-shadow: 0 0 20px rgba(255,255,255,0.2);
}

/* HOME PAGE DESCRIPTION */

.home-description {
  max-width: 800px;
  margin: 20px auto 30px auto;
  padding: 18px 25px;

  background: linear-gradient(
    to bottom right,
    rgba(40,40,40,0.78),
    rgba(15,15,15,0.72)
  );

  border: 1px solid rgba(255,255,255,0.15);
  border-radius: 18px;

  backdrop-filter: blur(10px);

  color: white;
  font-size: 18px;
  line-height: 1.6;
  text-align: center;

  box-shadow:
    0 0 20px rgba(0,0,0,0.45),
    0 0 10px rgba(255,255,255,0.08);
}

.home-button-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
  width: min(750px, 90%);
  margin: 20px auto 0 auto;
}

.home-button-grid a {
  text-decoration: none;
}

.home-button-grid button {
  width: 100%;
}

/* COURSES DESCRIPTION */

.courses-description {
  max-width: 950px;
  margin: 0 auto 15px auto;
  padding: 20px 25px;

  background: linear-gradient(
    to bottom right,
    rgba(40,40,40,0.78),
    rgba(15,15,15,0.72)
  );

  border: 1px solid rgba(255,255,255,0.15);
  border-radius: 18px;

  backdrop-filter: blur(10px);

  color: white;
  line-height: 1.7;
  text-align: center;

  box-shadow:
    0 0 20px rgba(0,0,0,0.45),
    0 0 10px rgba(255,255,255,0.08);
}

.course-features {
  max-width: 850px;
  margin: 15px auto 35px auto;

  background: linear-gradient(
    to bottom right,
    rgba(40,40,40,0.78),
    rgba(15,15,15,0.72)
  );

  border: 1px solid rgba(255,255,255,0.15);
  border-radius: 18px;

  padding: 20px 35px;

  text-align: left;

  box-shadow:
    0 0 20px rgba(0,0,0,0.45),
    0 0 10px rgba(255,255,255,0.08);
}

.course-features li {
  margin-bottom: 12px;
  line-height: 1.6;
}

.diagram-card {
  margin: 25px auto;
  padding: 18px;
  max-width: 520px;
  text-align: center;

  background: rgba(0,0,0,0.35);
  border: 1px solid rgba(255,255,255,0.15);
  border-radius: 18px;

  box-shadow: 0 0 18px rgba(0,0,0,0.35);
}

.content-image {
  display: block;
  max-width: 420px;
  width: 90%;
  margin: 0 auto;
  border-radius: 14px;
}

.diagram-card p {
  margin-top: 12px;
  font-size: 15px;
  color: rgba(255,255,255,0.85);
}

.title-orbit-wrapper {
  position: relative;
  display: inline-block;
  margin-bottom: 35px;
  overflow: visible;
}

/* METAL ENGINEERING TITLE BANNER */
.title-banner {
  position: absolute;
  top: 50%;
  left: 50%;

  width: 900px;
  height: 120px;

  transform: translate(-50%, -50%);
  z-index: 1;

  background:
    linear-gradient(
      135deg,
      #3b3b3b 0%,
      #9c9c9c 18%,
      #e6e6e6 35%,
      #777 50%,
      #d0d0d0 68%,
      #595959 100%
    );

  clip-path: polygon(
    7% 0%,
    93% 0%,
    100% 50%,
    93% 100%,
    7% 100%,
    0% 50%
  );

  border: 2px solid rgba(255,255,255,0.55);

  box-shadow:
    0 0 35px rgba(255,255,255,0.55),
    0 0 60px rgba(0,0,0,0.75),
    inset 0 0 25px rgba(255,255,255,0.45),
    inset 0 0 40px rgba(0,0,0,0.45);
}

/* INNER METAL PLATE */
.title-banner::before {
  content: "";
  position: absolute;
  inset: 10px;

  border: 2px solid rgba(255,255,255,0.35);

  clip-path: polygon(
    7% 0%,
    93% 0%,
    100% 50%,
    93% 100%,
    7% 100%,
    0% 50%
  );

  box-shadow:
    inset 0 0 18px rgba(0,0,0,0.55),
    0 0 12px rgba(255,255,255,0.18);
}

/* RULER/PLATE TEXTURE OVERLAY */
.title-banner::after {
  content: "";
  position: absolute;
  inset: 0;

  background:
    repeating-linear-gradient(
      90deg,
      rgba(255,255,255,0.15) 0px,
      rgba(255,255,255,0.15) 2px,
      transparent 2px,
      transparent 38px
    );

  opacity: 0.35;

  clip-path: polygon(
    7% 0%,
    93% 0%,
    100% 50%,
    93% 100%,
    7% 100%,
    0% 50%
  );
}

/* TITLE ABOVE BANNER */
.title-orbit-wrapper h1 {
  position: relative;
  z-index: 3;
  margin: 0;

  font-size: 52px;
  letter-spacing: 1px;
  color: white;

  text-shadow:
    0 0 8px black,
    0 0 16px black,
    0 0 25px rgba(255,255,255,0.9);
}

/* ORBIT ABOVE WORDS AND BANNER */
.orbit-container {
  position: absolute;
  top: 50%;
  left: 50%;

  width: 300px;
  height: 300px;

  transform: translate(-50%, -50%);
  pointer-events: none;
  z-index: 5;
}

/* COURSE INTRODUCTION */
.course-description{
  width: min(900px,95%);
  margin: 25px auto 35px auto;

  padding: 20px 30px;

  background: linear-gradient(
    to bottom right,
    rgba(70,70,70,0.75),
    rgba(30,30,30,0.75)
  );

  border-radius: 20px;

  border: 1px solid rgba(255,255,255,0.15);

  box-shadow:
    0 0 20px rgba(0,0,0,0.4);

  backdrop-filter: blur(10px);

  text-align: center;
}

.course-description h2{
  margin-top: 0;
  color: white;
}

.course-description p{
  color: rgba(255,255,255,0.9);
  line-height: 1.6;
  font-size: 17px;
}

/* HAMBURGER BUTTON */

.menu-button{
  position: fixed;

  top: 20px;
  left: 20px;

  font-size: 40px;

  color: white;

  cursor: pointer;

  z-index: 10000;
}


/* ==========================
   MENU BUTTON
========================== */

.menu-button{

  position: fixed;

  top: 20px;
  left: 20px;

  padding: 10px 18px;

  background: rgba(35,35,35,0.85);

  border: 1px solid rgba(255,255,255,0.2);

  border-radius: 15px;

  color: white;

  font-size: 26px;
  font-weight: bold;

  cursor: pointer;

  z-index: 10000;

  box-shadow:
    0 0 15px rgba(0,0,0,.4);

  transition: .3s;
}

.menu-button:hover{

  background: rgba(60,60,60,0.95);

  transform: scale(1.05);

}

.menu-button span{

  font-size: 18px;

  margin-left: 6px;

}

/* ==========================
   SIDE MENU
========================== */

.side-menu{

  position: fixed;

  top: 0;
  left: -280px;

  width: 260px;
  height: 100vh;

  background: rgba(20,20,20,0.96);

  backdrop-filter: blur(10px);

  transition: .4s;

  padding-top: 90px;

  z-index: 9999;

  overflow-y: auto;
}

.side-menu.open{

  left: 0;

}

.side-menu a{

  display: block;

  color: white;

  text-decoration: none;

  padding: 18px 25px;

  font-size: 20px;

  transition: .3s;
}

.side-menu a:hover{

  background: rgba(255,255,255,.15);

}

/* ==========================
   COURSES SUBMENU
========================== */

.courses-item{

  position: relative;

}

.submenu{

  display: none;

  position: absolute;

  left: 260px;

  top: 0;

  width: 260px;

  background: rgba(35,35,35,.96);

  backdrop-filter: blur(10px);

  border-radius: 0 10px 10px 0;

}

.courses-item:hover .submenu{

  display: block;

}

.submenu a{

  font-size: 17px;

}

/* COURSES DROPDOWN */

.courses-toggle{

  color: white;

  padding: 18px 25px;

  font-size: 20px;

  cursor: pointer;

  transition: .3s;

}

.courses-toggle:hover{

  background: rgba(255,255,255,.15);

}

.courses-submenu{

  display: none;

  background: rgba(255,255,255,.05);

}

.courses-submenu.open{

  display: block;

}

.courses-submenu a{

  padding-left: 45px;

  font-size: 17px;

}

/* RECTANGULAR CONVEYOR ORBIT */

.belt-orbit{
    position:absolute;
    top:50%;
    left:50%;

    width:920px;
    height:155px;

    transform:translate(-50%,-50%);

    z-index:5;

    pointer-events:none;
}

.belt-symbol{
    position:absolute;

    font-size:30px;

    color:rgba(255,255,255,.85);

    text-shadow:
      0 0 8px black,
      0 0 15px rgba(255,255,255,.8);

    offset-path: polygon(
      0% 0%,
      100% 0%,
      100% 100%,
      0% 100%
    );

    animation:beltSpin 24s linear infinite;
}

.s1  { animation-delay: 0s; }

.s2  { animation-delay: -1.5s; }

.s3  { animation-delay: -3s; }

.s4  { animation-delay: -4.5s; }

.s5  { animation-delay: -6s; }

.s6  { animation-delay: -7.5s; }

.s7  { animation-delay: -9s; }

.s8  { animation-delay: -10.5s; }

.s9  { animation-delay: -12s; }

.s10 { animation-delay: -13.5s; }

.s11 { animation-delay: -15s; }

.s12 { animation-delay: -16.5s; }

.s13 { animation-delay: -18s; }

.s14 { animation-delay: -19.5s; }

.s15 { animation-delay: -21s; }

.s16 { animation-delay: -22.5s; }

@keyframes beltSpin{

  from{
    offset-distance:0%;
  }

  to{
    offset-distance:100%;
  }

}