* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Pretendard', sans-serif;
}

body {
  background-color: #f9f9fb;
  color: #1a1a1a;
  transition: background-color 0.3s, color 0.3s;
}

body.dark {
  background-color: #1a1a1a;
  color: #f4f4f4;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px;
  background-color: #ffffff;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
  position: sticky;
  top: 0;
  z-index: 1000;
}

body.dark header {
  background-color: #2a2a2a;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo {
  height: 80px;
}

.header-right {
  display: flex;
  align-items: center;
  gap: 20px;
}

nav a {
  text-decoration: none;
  color: #1e60c5;
  font-weight: bold;
  padding: 6px 14px;
  border-radius: 6px;
  background-color: #e6f0ff;
  transition: background-color 0.2s;
}

nav a:hover {
  background-color: #cfe3ff;
}

body.dark nav a {
  background-color: #444;
  color: #fff;
}

#darkToggle {
  background: none;
  border: none;
  font-size: 1.4rem;
  cursor: pointer;
}

main {
  padding: 60px 20px;
  max-width: 1000px;
  margin: 0 auto;
}

.projects-section h2 {
  font-size: 2.5rem;
  margin-bottom: 40px;
  text-align: center;
}

.project-list {
  display: flex;
  flex-direction: column;
  gap: 30px;
}

.project-item {
  border-radius: 12px;
  background-color: #fff;
  padding: 20px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.05);
  transition: background-color 0.3s;
  position: relative;
}

body.dark .project-item {
  background-color: #2c2c2c;
}

.project-summary {
  display: flex;
  gap: 20px;
  align-items: center;
  cursor: default;
}

.project-img {
  width: 130px;
  height: 100px;
  object-fit: cover;
  border-radius: 8px;
}

.project-info h3 {
  font-size: 1.3rem;
  color: #1e60c5;
}

.project-info p {
  margin-top: 5px;
  color: #555;
}

.project-detail {
  margin-top: 20px;
  border-top: 1px solid #ccc;
  padding-top: 20px;
  display: none;
  animation: fadeIn 0.3s ease-in-out;
}

.project-item:hover .project-detail {
  display: block;
}

.project-detail p {
  font-size: 1rem;
  line-height: 1.6;
  color: #333;
}

.project-link {
  display: inline-block;
  margin: 15px 0;
  padding: 6px 14px;
  background-color: #1e60c5;
  color: white;
  border-radius: 6px;
  text-decoration: none;
  font-weight: bold;
  transition: background-color 0.2s;
}

.project-link:hover {
  background-color: #174c99;
}

.stack-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  padding: 0;
  margin: 15px 0;
}

.stack-list li {
  background-color: #e6f0ff;
  color: #1a1a1a;
  padding: 6px 10px;
  border-radius: 6px;
  font-size: 0.9rem;
}

.author {
  font-size: 1rem;
  margin-top: 10px;
  color: #555;
}

footer {
  text-align: center;
  padding: 30px 10px;
  font-size: 0.9rem;
  color: #777;
  background-color: #f1f1f1;
}

body.dark footer {
  background-color: #2a2a2a;
  color: #ccc;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 768px) {
  .project-summary {
    flex-direction: column;
    text-align: center;
  }

  .project-img {
    width: 100%;
    height: auto;
  }

  .project-info h3 {
    font-size: 1.1rem;
  }

  .stack-list {
    justify-content: center;
  }
}

body.dark .project-detail p {
  color: #ffffff;
}