body {
  font-family: Arial, sans-serif;
  background: #f7f7f7;
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.top-band {
  width: 100vw;
  background: linear-gradient(90deg, #174a7c 60%, #3498db 100%);
  padding: 18px 0 14px 0;
  box-shadow: 0 2px 12px 0 rgba(44, 62, 80, 0.10);
  display: flex;
  justify-content: center;
  align-items: center;
  position: fixed;
  top: 0;
  left: 0;
  z-index: 100;
}
.top-title {
  color: #fff;
  font-size: 2.1em;
  font-weight: bold;
  letter-spacing: 1px;
  text-shadow: 0 2px 8px rgba(44, 62, 80, 0.13);
}

.main-card {
  background: #fff;
  margin-top: 100px;
  padding: 32px 28px 28px 28px;
  border-radius: 18px;
  box-shadow: 0 6px 32px 0 rgba(44, 62, 80, 0.13), 0 1.5px 4px 0 rgba(44, 62, 80, 0.06);
  max-width: 950px;
  width: 100%;
}
h1 {
  text-align: center;
  color: #174a7c;
  margin-top: 0;
  margin-bottom: 28px;
  letter-spacing: 0.5px;
}
.converter, .charts {
  margin-bottom: 36px;
}
.converter {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 10px;
  margin-bottom: 18px;
}
.converter input, .converter select {
  padding: 8px;
  border: 1px solid #b3c6e0;
  border-radius: 6px;
  font-size: 1em;
  background: #f5faff;
  transition: border 0.2s;
  min-width: 90px;
}
.converter input:focus, .converter select:focus {
  border: 1.5px solid #3498db;
  outline: none;
  background: #eaf4fb;
}
.converter button {
  padding: 8px 18px;
  background: #3498db;
  color: white;
  border: none;
  border-radius: 7px;
  font-size: 1em;
  font-weight: bold;
  cursor: pointer;
  box-shadow: 0 2px 8px 0 rgba(44, 62, 80, 0.07);
  transition: background 0.2s;
  letter-spacing: 0.5px;
}
.converter button:hover {
  background: #217dbb;
}
#result {
  margin-top: 12px;
  font-size: 1.08em;
  color: #174a7c;
  background: #eaf4fb;
  border-radius: 8px;
  padding: 10px 14px;
  min-height: 28px;
  box-shadow: 0 1.5px 4px 0 rgba(44, 62, 80, 0.06);
  text-align: center;
}
.charts h2 {
  color: #174a7c;
  margin-bottom: 12px;
  margin-top: 0;
  text-align: center;
}
.charts select {
  margin-bottom: 12px;
  padding: 7px;
  border-radius: 6px;
  border: 1px solid #b3c6e0;
  background: #f5faff;
  font-size: 1em;
}
.charts {
  display: flex;
  flex-direction: column;
  align-items: center;
}
canvas {
  max-width: 900px;
  width: 100%;
  height: 400px !important;
  margin-top: 10px;
  background: #fff;
  border-radius: 8px;
  box-shadow: 0 2px 8px 0 rgba(44, 62, 80, 0.07);
  display: block;
  margin-left: auto;
  margin-right: auto;
}
@media (max-width: 1000px) {
  .main-card {
    max-width: 98vw;
    padding: 16px 6px 16px 6px;
  }
  canvas {
    max-width: 98vw;
    height: 300px !important;
  }
}
@media (max-width: 700px) {
  .converter {
    flex-direction: column;
    gap: 8px;
  }
}