body {
  font-family: "Inter", "Segoe UI", sans-serif;
  background: #f4f7f6;
  background-image: radial-gradient(
    circle at top right,
    #e0eafc 0%,
    #cfdef3 100%
  );
  color: #333;
  line-height: 1.6;
  padding: 60px 20px;
  min-height: 100vh;
}

.portfolio-container {
  max-width: 1100px;
  margin: 0 auto;
}

.portfolio-header {
  text-align: center;
  margin-bottom: 60px;
}

.portfolio-header h1 {
  font-size: 3.6rem;
  font-weight: 800;
  background: linear-gradient(135deg, #1f1c2c 0%, #928dab 100%);
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 10px;
  letter-spacing: -1px;
}

.portfolio-header p {
  font-size: 1.6rem;
  color: #555;
  font-weight: 500;
}

.exercise-list {
  display: flex;
  flex-wrap: wrap;
  gap: 30px;
}

.exercise-item {
  flex: 1 1 calc(33.333% - 30px);
  min-width: 300px;
  display: flex;
}

.exercise-card {
  display: flex;
  flex-direction: column;
  background: #ffffffd9;
  padding: 35px 30px;
  border-radius: 16px;
  text-decoration: none;

  border: 1px solid #ffffff;
  box-shadow: 0 10px 30px #0000000a;
  position: relative;
  overflow: hidden;
  transition: all 0.4s cubic-bezier(0.165, 0.84, 0.44, 1);
}

.exercise-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, #f05123, #ff7e5f, #feb47b);
  opacity: 0;
  transform: translateY(-4px);
  transition: all 0.4s ease;
}

.lesson-number {
  font-size: 1.3rem;
  font-weight: 800;
  color: #a0aab5;
  text-transform: uppercase;
  letter-spacing: 2px;
  margin-bottom: 15px;
  transition: all 0.3s ease;
}

.lesson-title {
  font-size: 2.2rem;
  color: #1a1a1a;
  margin-bottom: 15px;
  font-weight: 700;
  letter-spacing: -0.5px;
  transition: color 0.3s ease;
}

.lesson-desc {
  font-size: 1.45rem;
  color: #666;
  flex-grow: 1;
  margin-bottom: 30px;
}

.action-text {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  font-weight: 600;
  color: #6c757d;
  background-color: #f1f3f5;
  padding: 10px 20px;
  border-radius: 30px;
  width: max-content;
  transition: all 0.3s ease;
}

.exercise-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 20px 40px rgba(240, 81, 35, 0.15);
  background: rgba(255, 255, 255, 1);
}

.exercise-card:hover::before {
  opacity: 1;
  transform: translateY(0);
}

.exercise-card:hover .lesson-title {
  color: #f05123;
}

.exercise-card:hover .lesson-number {
  background: linear-gradient(45deg, #f05123, #ff7e5f);
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.exercise-card:hover .action-text {
  background: linear-gradient(90deg, #f05123, #ff7e5f);
  color: #ffffff;
  box-shadow: 0 4px 15px rgba(240, 81, 35, 0.4);
  transform: translateX(5px);
}

.back-navigation {
  text-align: center;
  margin-top: 60px;
}

.btn-back {
  display: inline-block;
  font-size: 1.45rem;
  font-weight: 600;
  color: #6c757d;
  text-decoration: none;
  padding: 12px 25px;
  border-radius: 30px;
  background-color: rgba(255, 255, 255, 0.6);
  border: 1px solid rgba(255, 255, 255, 1);
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.02);
  transition: all 0.3s ease;
}

.btn-back:hover {
  color: #f05123;
  background-color: #ffffff;
  box-shadow: 0 8px 25px rgba(240, 81, 35, 0.15);
  transform: translateY(-3px);
}