body {
  font-family: 'Segoe UI', 'Noto Sans TC', Arial, sans-serif;
  margin: 0;
  background: #f7f8fa;
  color: #222;
}
header {
  background: #2d8cf0;
  color: #fff;
  padding: 1.5rem 1rem 1rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
header h1 {
  margin: 0;
  font-size: 2rem;
  letter-spacing: 2px;
}
#lang-toggle {
  background: #fff;
  color: #2d8cf0;
  border: none;
  border-radius: 4px;
  padding: 0.5rem 1rem;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.2s;
}
#lang-toggle:hover {
  background: #e6f0fa;
}
main {
  max-width: 700px;
  margin: 2rem auto;
  padding: 1rem;
  background: #fff;
  border-radius: 10px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.06);
}
.intro {
  margin-bottom: 2rem;
}
.converter {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}
.convert-section {
  background: #f5f8fd;
  border-radius: 8px;
  padding: 1rem;
  margin-bottom: 0;
  box-shadow: 0 1px 4px rgba(0,0,0,0.03);
}
.convert-section h3 {
  margin-top: 0;
  margin-bottom: 0.5rem;
  font-size: 1.15rem;
  background: #e6f0fa;
  padding: 0.5rem;
  border-radius: 6px;
}
textarea {
  width: 100%;
  min-height: 120px;
  font-size: 1rem;
  padding: 0.5rem;
  border-radius: 4px;
  border: 1px solid #d0d7de;
  margin-bottom: 0.5rem;
  resize: vertical;
  box-sizing: border-box;
}
button {
  background: #2d8cf0;
  color: #fff;
  border: none;
  border-radius: 4px;
  padding: 0.5rem 1.2rem;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.2s;
}
button:hover {
  background: #1766b3;
}
.output-row {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
}
.output-area {
  width: 100%;
  min-height: 90px;
  background: #f9fafb;
  border: 1px solid #e0e0e0;
  border-radius: 4px;
  padding: 0.5rem;
  font-size: 1.35rem;
  font-family: 'Noto Sans', 'Segoe UI', Arial, sans-serif;
  margin-bottom: 0.5rem;
  word-break: break-word;
  white-space: pre-wrap;
  line-height: 1.7;
}
.copy-btn {
  background: #2d8cf0;
  color: #fff;
  border: none;
  border-radius: 4px;
  padding: 0.6rem 1.1rem;
  font-size: 1.05rem;
  cursor: pointer;
  transition: background 0.2s;
  margin-left: 0.2rem;
  height: fit-content;
  align-self: flex-start;
  min-width: 60px;
}
.copy-btn:hover {
  background: #1766b3;
}
.pinyin-chart {
  margin-top: 2rem;
}
#pinyin-chart-table {
  overflow-x: auto;
}
footer {
  text-align: center;
  color: #888;
  padding: 2rem 1rem 1rem 1rem;
  font-size: 0.95rem;
}
.main-nav {
  background: #e6f0fa;
  border-bottom: 1px solid #d0d7de;
  padding: 0.5rem 1rem;
}
.main-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
}
.main-nav li {
  margin: 0;
}
.main-nav a {
  color: #2d8cf0;
  text-decoration: none;
  font-weight: 500;
  font-size: 1.08rem;
  padding: 0.3rem 0.7rem;
  border-radius: 4px;
  transition: background 0.2s, color 0.2s;
}
.main-nav a:hover, .main-nav a:focus {
  background: #2d8cf0;
  color: #fff;
}
@media (max-width: 600px) {
  main {
    max-width: 98vw;
    margin: 0.5rem auto;
    padding: 0.5rem;
    border-radius: 0;
    box-shadow: none;
  }
  .convert-section {
    padding: 0.5rem;
  }
  .converter {
    gap: 1rem;
  }
  .output-area, textarea {
    font-size: 1.1rem;
    min-height: 70px;
  }
  .copy-btn {
    font-size: 1rem;
    padding: 0.5rem 0.8rem;
    min-width: 48px;
  }
  header {
    flex-direction: column;
    align-items: flex-start;
    padding: 1rem 0.5rem 0.5rem 0.5rem;
  }
  .main-nav ul {
    gap: 0.7rem;
    flex-direction: column;
  }
  .main-nav {
    padding: 0.5rem 0.5rem;
  }
}