The provided code adds CSS styles for a design progression section to showcase the evolution of a project, including responsive design considerations.
```

```
/* Project Detail Page Styles */

.project-detail {
  padding: 2rem 0 4rem;
  background: var(--white);
  min-height: 100vh;
}

.project-header {
  margin-bottom: 4rem;
}

.back-link {
  display: inline-flex;
  align-items: center;
  color: var(--sage-gray);
  text-decoration: none;
  font-weight: 500;
  margin-bottom: 2rem;
  transition: color 0.3s ease;
}

.back-link:hover {
  color: var(--dark-gray);
}

.project-header h1 {
  font-family: var(--font-accent);
  font-size: clamp(2.5rem, 5vw, 4rem);
  margin-bottom: 1rem;
  background: var(--gradient-sage);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.1;
  word-wrap: break-word;
  overflow-wrap: break-word;
  hyphens: auto;
}

.project-subtitle {
  font-size: clamp(1.1rem, 2.5vw, 1.4rem);
  color: var(--medium-gray);
  margin-bottom: 3rem;
  max-width: 100%;
  word-wrap: break-word;
  overflow-wrap: break-word;
}

.project-hero {
  position: relative;
  border-radius: 20px;
  overflow: hidden;
  box-shadow: var(--shadow-medium);
  margin-bottom: 3rem;
}

.project-hero img {
  width: 100%;
  height: 400px;
  object-fit: cover;
}

.project-actions {
  position: absolute;
  bottom: 2rem;
  right: 2rem;
}

.project-content {
  max-width: 900px;
}

.project-video {
  position: relative;
  width: 100%;
  margin-bottom: 3rem;
  border-radius: 15px;
  overflow: hidden;
  box-shadow: var(--shadow-medium);
}

.project-video video {
  width: 100%;
  height: auto;
  display: block;
}

.project-section {
  margin-bottom: 4rem;
  padding-bottom: 3rem;
  border-bottom: 1px solid var(--light-gray);
}

.project-section:last-child {
  border-bottom: none;
}

.project-section h2 {
  font-family: var(--font-accent);
  font-size: clamp(2.2rem, 4vw, 3rem);
  margin-bottom: 2rem;
  color: var(--dark-gray);
  font-weight: 700;
  letter-spacing: -0.01em;
}

.project-section h3 {
  font-size: clamp(1.4rem, 2.5vw, 1.8rem);
  margin-bottom: 1rem;
  color: var(--dark-gray);
  font-weight: 600;
}

.project-section p {
  font-size: clamp(1.1rem, 2.5vw, 1.25rem);
  line-height: 1.7;
  color: var(--medium-gray);
  margin-bottom: 1.5rem;
}

.project-section ul {
  margin-left: 1.5rem;
  margin-bottom: 2rem;
}

.project-section li {
  font-size: clamp(1.1rem, 2.5vw, 1.25rem);
  line-height: 1.7;
  color: var(--medium-gray);
  margin-bottom: 0.75rem;
}

.project-overview {
  background: linear-gradient(135deg, var(--light-gray) 0%, #e2e8f0 100%);
  border-radius: 20px;
  padding: 3rem;
  margin-bottom: 4rem;
}

.overview-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.overview-item h3 {
  font-size: 1.1rem;
  color: var(--sage-gray);
  margin-bottom: 0.5rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-weight: 600;
}

.overview-item p {
  font-size: 1.2rem;
  color: var(--dark-gray);
  font-weight: 600;
  margin: 0;
}

.challenge-points,
.solution-features {
  background: rgba(138, 154, 154, 0.05);
  border-left: 4px solid var(--sage-gray);
  padding: 2rem;
  border-radius: 0 15px 15px 0;
  margin: 2rem 0;
}

.process-steps {
  display: grid;
  gap: 2rem;
  margin-top: 2rem;
}

.process-step {
  background: var(--white);
  border: 2px solid var(--light-gray);
  border-radius: 15px;
  padding: 2rem;
  position: relative;
  transition: all 0.3s ease;
}

.process-step:hover {
  border-color: var(--sage-gray);
  transform: translateY(-2px);
  box-shadow: var(--shadow-soft);
}

.process-step h3 {
  color: var(--sage-gray);
  margin-bottom: 1rem;
}

/* Design Progression */
.design-progression {
  display: flex;
  flex-direction: column;
  gap: 3rem;
  margin: 2rem 0;
}

.progression-item {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  align-items: center;
  padding: 2rem;
  background: var(--white);
  border-radius: 15px;
  box-shadow: var(--shadow-soft);
  border-left: 4px solid var(--sage-gray);
}

.progression-item:nth-child(2) {
  border-left-color: var(--soft-blue);
}

.progression-item:nth-child(3) {
  border-left-color: var(--warm-gray);
}

.progression-item:nth-child(even) {
  grid-template-columns: 1fr 1fr;
}

.progression-item:nth-child(even) .progression-image {
  order: 2;
}

.progression-item:nth-child(even) .progression-content {
  order: 1;
}

.progression-image {
  border-radius: 10px;
  overflow: hidden;
  box-shadow: var(--shadow-medium);
}

.progression-image img {
  width: 100%;
  height: auto;
  display: block;
  transition: transform 0.3s ease;
}

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

.progression-content h3 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
  color: var(--dark-gray);
  font-weight: 700;
}

.progression-content p {
  color: var(--medium-gray);
  line-height: 1.7;
  font-size: 1.1rem;
}

@media (max-width: 768px) {
  .progression-item {
    grid-template-columns: 1fr !important;
    gap: 1.5rem;
  }

  .progression-item:nth-child(even) .progression-image,
  .progression-item:nth-child(even) .progression-content {
    order: unset;
  }
}

/* Results Grid */
.results-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 2rem;
  margin: 3rem 0;
}

.result-item {
  text-align: center;
  background: var(--white);
  border: 2px solid var(--light-gray);
  border-radius: 15px;
  padding: 2rem 1rem;
  transition: all 0.3s ease;
}

.result-item:hover {
  border-color: var(--sage-gray);
  transform: translateY(-3px);
  box-shadow: var(--shadow-soft);
}

.result-item h3 {
  font-size: clamp(2rem, 4vw, 3rem);
  color: var(--sage-gray);
  margin-bottom: 0.5rem;
  font-weight: 800;
}

.result-item p {
  color: var(--medium-gray);
  font-weight: 500;
  margin: 0;
  font-size: 1rem;
}

.testimonial {
  background: linear-gradient(135deg, rgba(138, 154, 154, 0.05), rgba(122, 139, 163, 0.05));
  border-radius: 15px;
  padding: 2.5rem;
  margin: 3rem 0;
  border-left: 4px solid var(--sage-gray);
}

.testimonial blockquote {
  font-size: clamp(1.2rem, 3vw, 1.4rem);
  line-height: 1.6;
  color: var(--dark-gray);
  font-style: italic;
  margin: 0 0 1rem 0;
}

.testimonial cite {
  color: var(--sage-gray);
  font-weight: 600;
  font-style: normal;
}

.smartie-breakdown {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.smartie-item {
  background: var(--white);
  border: 2px solid var(--light-gray);
  border-radius: 15px;
  padding: 1.5rem;
  transition: all 0.3s ease;
}

.smartie-item:hover {
  border-color: var(--sage-gray);
  transform: translateY(-2px);
  box-shadow: var(--shadow-soft);
}

.smartie-item h3 {
  color: var(--sage-gray);
  margin-bottom: 0.75rem;
  font-size: 1.3rem;
}

.smartie-item p {
  color: var(--medium-gray);
  margin: 0;
  font-size: 1rem;
  line-height: 1.5;
}

.technical-details {
  background: rgba(122, 139, 163, 0.05);
  border-radius: 15px;
  padding: 2rem;
  margin: 2rem 0;
}

.technical-details h3 {
  color: var(--sage-gray);
  margin-bottom: 1rem;
  margin-top: 2rem;
}

.technical-details h3:first-child {
  margin-top: 0;
}

/* Responsive Design */
@media (max-width: 768px) {
  .project-detail {
    padding: 6rem 0 2rem;
  }

  .project-header h1 {
    font-size: clamp(2rem, 6vw, 3rem);
    line-height: 1.1;
  }

  .project-subtitle {
    font-size: clamp(1rem, 3vw, 1.2rem);
    margin-bottom: 2rem;
  }

  .project-hero {
    margin-bottom: 2rem;
  }

  .project-hero img {
    height: 250px;
  }

  .project-actions {
    position: static;
    text-align: center;
    padding: 1.5rem;
    background: rgba(255, 255, 255, 0.95);
  }

  .project-video {
    margin-bottom: 2rem;
  }

  .project-overview {
    padding: 2rem;
    margin-bottom: 3rem;
  }

  .overview-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

  .results-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }

  .smartie-breakdown {
    grid-template-columns: 1fr;
  }

  .testimonial {
    padding: 1.5rem;
  }
}

/* Lightbox Styles */
.lightbox {
  display: none;
  position: fixed;
  z-index: 2000;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.9);
  backdrop-filter: blur(5px);
}

.lightbox.active {
  display: flex;
  align-items: center;
  justify-content: center;
}

.lightbox-content {
  position: relative;
  max-width: 90%;
  max-height: 90%;
  margin: auto;
}

.lightbox img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
  border-radius: 10px;
  box-shadow: 0 10px 50px rgba(0, 0, 0, 0.5);
}

.lightbox-close {
  position: absolute;
  top: -40px;
  right: 0;
  color: #fff;
  font-size: 2rem;
  font-weight: bold;
  cursor: pointer;
  transition: opacity 0.3s ease;
  background: none;
  border: none;
  padding: 5px;
}

.lightbox-close:hover {
  opacity: 0.7;
}

.progression-image {
  cursor: pointer;
}

.progression-image:hover img {
  transform: scale(1.05);
  opacity: 0.9;
}

@media (max-width: 480px) {
  .project-header h1 {
    font-size: clamp(1.8rem, 8vw, 2.5rem);
    line-height: 1.1;
    margin-bottom: 0.75rem;
  }

  .project-subtitle {
    font-size: clamp(0.95rem, 4vw, 1.1rem);
    margin-bottom: 1.5rem;
    line-height: 1.5;
  }

  .project-overview {
    padding: 1.5rem;
  }

  .process-step,
  .challenge-points,
  .solution-features {
    padding: 1.5rem;
  }

  .results-grid {
    grid-template-columns: 1fr;
  }

  .testimonial {
    padding: 1rem;
  }

  .lightbox-close {
    top: -30px;
    font-size: 1.5rem;
  }
}
/* Add any project detail specific styles here */

/* Progression Section Styles */
.progression-container {
  display: flex;
  flex-direction: column;
  gap: 3rem;
  margin-top: 2rem;
}

.progression-item {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  align-items: center;
  padding: 2rem;
  background: var(--white);
  border-radius: 12px;
  border: 2px solid var(--light-gray);
  box-shadow: var(--shadow-soft);
  transition: all 0.3s ease;
}

.progression-item:nth-child(even) {
  grid-template-columns: 1fr 1fr;
}

.progression-item:nth-child(even) .progression-video {
  order: 2;
}

.progression-item:nth-child(even) .progression-content {
  order: 1;
}

.progression-item:hover {
  border-color: var(--sage-gray);
  transform: translateY(-2px);
}

.progression-video {
  border-radius: 8px;
  overflow: hidden;
  box-shadow: var(--shadow-medium);
}

.progression-video video,
.progression-video img {
  width: 100%;
  height: auto;
  display: block;
}

.progression-content h3 {
  color: var(--sage-gray);
  margin-bottom: 1rem;
  font-size: 1.5rem;
  font-weight: 600;
}

.progression-content p {
  color: var(--medium-gray);
  line-height: 1.6;
}

@media (max-width: 768px) {
  .progression-item {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .progression-item:nth-child(even) .progression-video {
    order: 1;
  }

  .progression-item:nth-child(even) .progression-content {
    order: 2;
  }
}