:root {
  --bg-primary: #424658;
  --bg-panel: #E0CDB2;
  --font-color: #E0CDB2;
  --accent-primary: #81a3c6;
  --accent-secondary: #2c6aa8;
  --white: #ffffff;
  --font-sans: "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

* {
  box-sizing: border-box;
}

html, body {
  height: 100%;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--font-color);
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 20px;
  min-height: 100vh;
}

#app {
  width: 100%;
  max-width: 980px;
  background: var(--bg-panel);
  border-radius: 9px;
  box-shadow: 0 7.2px 21.6px rgba(12, 20, 40, 0.12);
  padding: 12.6px;
}

.app-title {
  font-family: sans-serif;
  text-align: center;
  color: var(--bg-primary);
  font-size: 1.8em;
  font-weight: bold;
  margin: 0 0 12.6px 0;
}

.app-title a {
  margin-left: 0.5rem;
  font-family: sans-serif;
  font-size: 0.5em;
  font-style: italic;
  text-decoration: underline;
  color: var(--bg-primary);
  transition: color 0.3s ease;
}

.app-title a:hover {
  color: rgb(0, 51, 255);
}

.converter-container {
  background: var(--bg-primary);
  border-radius: 9px;
  padding: 18px;
}

/* Category Buttons */
.category-buttons {
  display: flex;
  gap: 9px;
  margin-bottom: 18px;
  flex-wrap: wrap;
  justify-content: center;
}

.category-btn {
  flex: 1 1 126px;
  padding: 10.8px 14.4px;
  border: none;
  border-radius: 7.2px;
  background: var(--accent-primary);
  color: var(--white);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  min-width: 90px;
}

.category-btn:hover {
  background: var(--accent-secondary);
  transform: translateY(-1.8px);
  box-shadow: 0 3.6px 7.2px rgba(0, 0, 0, 0.2);
}

.category-btn.active {
  background: var(--accent-secondary);
  box-shadow: 0 0 0 2.7px rgba(44, 106, 168, 0.3);
}

/* Conversion Fields */
.conversion-fields {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14.4px;
  margin-bottom: 18px;
}

.field-group {
  display: flex;
  flex-direction: column;
  gap: 7.2px;
}

.field-group label {
  font-size: 0.81rem;
  font-weight: 600;
  color: var(--font-color);
}

.field-group input {
  padding: 10.8px;
  border: 1px solid #c8d6e5;
  border-radius: 5.4px;
  font-size: 0.99rem;
  background: var(--white);
  color: var(--bg-primary);
  font-weight: 500;
}

.field-group input:focus {
  outline: none;
  border-color: var(--accent-secondary);
  box-shadow: 0 0 0 2.7px rgba(44, 106, 168, 0.1);
}

.field-group input[readonly] {
  background: #f5f5f5;
  cursor: default;
}

/* Unit Selectors */
.unit-selectors {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14.4px;
}

.selector-group {
  display: flex;
  flex-direction: column;
  gap: 7.2px;
}

.selector-group label {
  font-size: 0.81rem;
  font-weight: 600;
  color: var(--font-color);
}

.selector-group select {
  padding: 7.2px;
  border: 1px solid #c8d6e5;
  border-radius: 5.4px;
  font-size: 0.9rem;
  background: var(--white);
  color: var(--bg-primary);
  cursor: pointer;
  overflow-y: auto;
}

.selector-group select:focus {
  outline: none;
  border-color: var(--accent-secondary);
  box-shadow: 0 0 0 2.7px rgba(44, 106, 168, 0.1);
}

.selector-group select option {
  padding: 7.2px;
}

.selector-group select option:hover {
  background: var(--accent-primary);
}

/* Currency Status Message */
.currency-status {
  margin-top: 14.4px;
  padding: 10.8px;
  border-radius: 5.4px;
  background: rgba(255, 255, 255, 0.1);
  color: var(--font-color);
  font-size: 0.765rem;
  text-align: center;
}

.currency-status.hidden {
  display: none;
}

.currency-status.loading {
  background: rgba(129, 163, 198, 0.2);
}

.currency-status.error {
  background: rgba(255, 100, 100, 0.2);
  color: #ffcccc;
}

/* Responsive Design */
@media (max-width: 768px) {
  .category-buttons {
    gap: 7.2px;
  }

  .category-btn {
    flex: 1 1 108px;
    padding: 9px 10.8px;
    font-size: 0.81rem;
  }

  .conversion-fields {
    gap: 10.8px;
  }

  .unit-selectors {
    gap: 10.8px;
  }
}

@media (max-width: 520px) {
  body {
    padding: 9px;
  }

  #app {
    padding: 9px;
  }

  .app-title {
    font-size: 1.35em;
  }

  .converter-container {
    padding: 13.5px;
  }

  .category-buttons {
    gap: 5.4px;
  }

  .category-btn {
    flex: 1 1 100%;
    min-width: auto;
    font-size: 0.765rem;
    padding: 9px;
  }

  .conversion-fields {
    grid-template-columns: 1fr;
    gap: 10.8px;
  }

  .unit-selectors {
    grid-template-columns: 1fr;
    gap: 10.8px;
  }

  .field-group input {
    font-size: 0.9rem;
  }

  .selector-group select {
    font-size: 0.81rem;
  }
}