/* Section container */
.lecture-problem-solution {
  background: #fff;
  padding: 60px 20px;
  margin: auto;
}

/* Header */
.stepper-header {
  text-align: center;
  margin-bottom: 40px;
}

.stepper-main-title {
  font-size: 2.8rem;
  font-weight: 700;
  color: #111;
  margin-bottom: 10px;
}

.stepper-sub-title {
  font-size: 1.6rem;
  color: #555;
  max-width: 700px;
  margin: 0 auto;
}

.stepper-item {
  position: relative;
  margin-bottom: 60px;
}

/* Timeline icons (left dots) */
.stepper-icon {
  background: #fff;
  border: 3px solid #222;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  text-align: center;
  line-height: 35px;
  font-size: 18px;
  color: #222;
}

.stepper-item.challenge .stepper-icon {
  background: #ffe5e5;
  border-color: #ff6b6b;
  color: #ff6b6b;
}

.stepper-item.solution .stepper-icon {
  background: #e0f7fa;
  border-color: #00bcd4;
  color: #00bcd4;
}

/* Step Content */
.stepper-content {
  margin-left: 20px;
}

.stepper-title {
  font-size: 2rem;
  font-weight: 600;
  margin-bottom: 15px;
}

.stepper-text {
  font-size: 1.6rem;
  color: #444;
  line-height: 1.7;
}

/* Solution Cards */
.stepper-solutions-list {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 20px;
  margin-top: 20px;
}

.stepper-solution-card {
  background: #f9f9f9;
  border-radius: 12px;
  padding: 20px;
  width:230px;
  height:230px;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.04);
  cursor: pointer;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: background 0.3s ease;
}

/* Icon wrapper */
.solution-icon-wrapper {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 10rem;
  min-height: 10rem;
}

/* Font Awesome Icon */
.solution-icon-wrapper i {
  font-size: 5.5rem;
  width: 10rem;
  height: 10rem;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  transition: opacity 0.3s ease;
}

/* Text (hidden initially) */
.solution-text {
  position: absolute;
  font-size: 1.8rem;
  color: #222;
  width:200px;
  opacity: 0;
  transition: opacity 0.3s ease;
  font-weight: 500;
}

/* Hover Effect */
.stepper-solution-card:hover i {
  opacity: 0;
}

.stepper-solution-card:hover .solution-text {
  opacity: 1;
}

/* Responsive Design */
@media (max-width: 768px) {
  .stepper-main-title {
    font-size: 2rem;
  }

  .stepper-sub-title {
    font-size: 1.4rem;
  }

  .stepper-title {
    font-size: 1.6rem;
  }

  .stepper-text,
  .solution-text {
    font-size: 1.4rem;
  }

  .stepper-solutions-list {
    gap: 15px;
  }
}