* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: #f5f7fa;
  color: #1a1a1a;
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 20px;
}

header {
  background: #fff;
  padding: 24px;
  border-radius: 12px;
  margin-bottom: 24px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}

header h1 {
  font-size: 24px;
  font-weight: 600;
  color: #0066b3;
}

main {
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin-bottom: 80px;
}

.card {
  background: #fff;
  border-radius: 12px;
  padding: 24px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}

.card h2 {
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 20px;
  color: #1a1a1a;
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-weight: 500;
  margin-bottom: 8px;
  color: #333;
}

.input-with-unit {
  display: flex;
  align-items: center;
  gap: 12px;
}

.input-with-unit input {
  flex: 1;
  padding: 12px 16px;
  border: 2px solid #e0e0e0;
  border-radius: 8px;
  font-size: 16px;
  transition: border-color 0.2s;
}

.input-with-unit input:focus {
  outline: none;
  border-color: #0066b3;
}

.input-with-unit .unit {
  color: #666;
  font-weight: 500;
  white-space: nowrap;
}

select {
  width: 100%;
  padding: 12px 16px;
  border: 2px solid #e0e0e0;
  border-radius: 8px;
  font-size: 16px;
  background: #fff;
  cursor: pointer;
  transition: border-color 0.2s;
}

select:focus {
  outline: none;
  border-color: #0066b3;
}

.btn-primary {
  width: 100%;
  padding: 14px 24px;
  background: #0066b3;
  color: #fff;
  border: none;
  border-radius: 8px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
}

.btn-primary:hover {
  background: #0052a0;
}

.btn-secondary {
  padding: 10px 20px;
  background: #f0f0f0;
  color: #333;
  border: none;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.2s;
}

.btn-secondary:hover {
  background: #e0e0e0;
}

.result-block {
  margin-top: 24px;
  padding: 24px;
  background: #f8f9fa;
  border-radius: 12px;
  border-left: 4px solid #0066b3;
}

.result-main {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
  padding-bottom: 20px;
  border-bottom: 2px solid #e0e0e0;
}

.result-label {
  font-size: 18px;
  font-weight: 500;
  color: #666;
}

.result-value {
  font-size: 36px;
  font-weight: 700;
  color: #0066b3;
}

.result-details h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 12px;
  color: #333;
}

.detail-row {
  display: flex;
  justify-content: space-between;
  padding: 8px 0;
  font-size: 15px;
}

.detail-row span:first-child {
  color: #666;
}

.detail-row span:last-child {
  font-weight: 500;
  color: #1a1a1a;
}

.formula-block {
  margin-top: 20px;
  padding-top: 20px;
  border-top: 1px solid #e0e0e0;
}

.formula-block h3 {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 8px;
  color: #666;
}

.formula-block p {
  font-family: "Courier New", monospace;
  font-size: 14px;
  background: #fff;
  padding: 12px;
  border-radius: 6px;
  color: #1a1a1a;
}

.history-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.history-header h2 {
  margin-bottom: 0;
}

.table-wrapper {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th, td {
  text-align: left;
  padding: 12px;
  border-bottom: 1px solid #e0e0e0;
}

th {
  font-weight: 600;
  color: #666;
  font-size: 14px;
  background: #f8f9fa;
}

td {
  font-size: 14px;
}

.no-history {
  text-align: center;
  color: #999;
  padding: 20px;
  display: none;
}

.fab {
  position: fixed;
  bottom: 24px;
  right: 24px;
  padding: 14px 24px;
  background: #1a1a1a;
  color: #fff;
  border: none;
  border-radius: 50px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
  transition: background 0.2s;
}

.fab:hover {
  background: #333;
}

.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0,0,0,0.5);
  z-index: 1000;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.modal.on {
  display: flex;
}

.modal-content {
  background: #fff;
  border-radius: 12px;
  max-width: 600px;
  width: 100%;
  max-height: 80vh;
  overflow-y: auto;
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 24px;
  border-bottom: 1px solid #e0e0e0;
}

.modal-header h2 {
  font-size: 20px;
  font-weight: 600;
}

.btn-close {
  background: none;
  border: none;
  font-size: 32px;
  cursor: pointer;
  color: #999;
  line-height: 1;
}

.btn-close:hover {
  color: #333;
}

#presetsContainer {
  padding: 24px;
}

.preset-card {
  background: #f8f9fa;
  padding: 20px;
  border-radius: 8px;
  margin-bottom: 20px;
}

.preset-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}

.preset-header h3 {
  font-size: 16px;
  font-weight: 600;
}

.btn-delete {
  background: #ff4444;
  color: #fff;
  border: none;
  border-radius: 6px;
  padding: 6px 12px;
  font-size: 12px;
  cursor: pointer;
}

.btn-delete:hover {
  background: #cc0000;
}

.preset-inputs {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.preset-inputs .form-group {
  margin-bottom: 0;
}

.preset-inputs label {
  font-size: 13px;
  color: #666;
  margin-bottom: 6px;
}

.preset-inputs input {
  width: 100%;
  padding: 10px 12px;
  border: 2px solid #e0e0e0;
  border-radius: 6px;
  font-size: 14px;
}

.preset-inputs input:focus {
  outline: none;
  border-color: #0066b3;
}

.modal-footer {
  padding: 20px 24px;
  border-top: 1px solid #e0e0e0;
  display: flex;
  justify-content: flex-end;
}

.error-message {
  background: #fff0f0;
  border: 1px solid #ffcccc;
  color: #cc0000;
  padding: 12px;
  border-radius: 6px;
  margin-bottom: 16px;
  font-size: 14px;
}

@media (max-width: 600px) {
  .preset-inputs {
    grid-template-columns: 1fr;
  }
  
  .result-value {
    font-size: 28px;
  }
  
  .history-header {
    flex-direction: column;
    gap: 12px;
    align-items: flex-start;
  }
}