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

:root {
  --primary-color: #667eea;
  --secondary-color: #764ba2;
  --success-color: #48bb78;
  --error-color: #f56565;
  --text-dark: #2d3748;
  --text-light: #718096;
  --bg-light: #f7fafc;
  --border-color: #e2e8f0;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 20px 40px rgba(0, 0, 0, 0.15);
}

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background-color: var(--bg-light);
  position: relative;
  overflow-x: hidden;
}

.background-gradient {
  position: fixed;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  animation: gradientShift 15s ease infinite;
  z-index: -1;
  opacity: 0.1;
}

@keyframes gradientShift {
  0%, 100% { transform: translate(0, 0); }
  50% { transform: translate(50px, 50px); }
}

.container {
  background-color: #ffffff;
  padding: 3rem;
  border-radius: 1.5rem;
  box-shadow: var(--shadow-lg);
  width: 90%;
  max-width: 500px;
  animation: slideIn 0.6s ease;
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.header {
  text-align: center;
  margin-bottom: 2.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 2px solid var(--border-color);
}

.header i {
  font-size: 2.5rem;
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 0.5rem;
  display: block;
}

.header h1 {
  font-size: 2rem;
  color: var(--text-dark);
  margin: 0.5rem 0;
  font-weight: 700;
}

.header .subtitle {
  color: var(--text-light);
  font-size: 0.95rem;
  margin: 0.5rem 0 0 0;
}

/* Skeleton Loading */
.skeleton-loader {
  animation: fadeOut 0.3s ease forwards;
}

.skeleton-loader.hidden {
  display: none;
}

@keyframes fadeOut {
  to {
    opacity: 0;
    visibility: hidden;
  }
}

.skeleton-input,
.skeleton-dropdown,
.skeleton-msg,
.skeleton-button {
  height: 3rem;
  background: linear-gradient(90deg, var(--border-color) 25%, #f0f0f0 50%, var(--border-color) 75%);
  background-size: 200% 100%;
  animation: skeletonLoading 1.5s infinite;
  border-radius: 0.75rem;
  margin-bottom: 1.5rem;
}

.skeleton-dropdown {
  height: 4rem;
}

.skeleton-msg {
  height: 2rem;
}

@keyframes skeletonLoading {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

#mainForm.hidden {
  display: none;
}

#mainForm {
  animation: fadeInForm 0.5s ease;
}

@keyframes fadeInForm {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

.amount-section {
  margin-bottom: 2rem;
}

.amount-section label {
  display: block;
  color: var(--text-dark);
  font-weight: 600;
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
}

.input-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

.input-wrapper i {
  position: absolute;
  left: 1rem;
  color: var(--primary-color);
  font-size: 1.1rem;
}

#amountInput {
  width: 100%;
  border: 2px solid var(--border-color);
  outline: none;
  border-radius: 0.75rem;
  font-size: 1rem;
  height: 3rem;
  padding: 0 1rem 0 2.8rem;
  transition: all 0.3s ease;
  background-color: var(--bg-light);
  color: var(--text-dark);
}

#amountInput:focus {
  border-color: var(--primary-color);
  background-color: white;
  box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

#amountInput:hover {
  border-color: var(--primary-color);
}

.dropdown {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  margin: 2rem 0;
  flex-wrap: wrap;
}

.currency-box {
  flex: 1;
  min-width: 160px;
}

.currency-box label {
  display: block;
  color: var(--text-dark);
  font-weight: 600;
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
}

.select {
  display: flex;
  align-items: center;
  border: 2px solid var(--border-color);
  border-radius: 0.75rem;
  padding: 0.5rem;
  background-color: var(--bg-light);
  transition: all 0.3s ease;
  gap: 0.5rem;
}

.select:hover {
  border-color: var(--primary-color);
  box-shadow: 0 0 0 2px rgba(102, 126, 234, 0.1);
}

.select img {
  width: 2rem;
  height: auto;
  border-radius: 0.35rem;
}

.select select {
  flex: 1;
  border: none;
  outline: none;
  background: transparent;
  font-size: 1rem;
  color: var(--text-dark);
  cursor: pointer;
  font-weight: 600;
}

.swap-btn {
  width: 3rem;
  height: 3rem;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  color: white;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease;
  font-size: 1.2rem;
  margin-top: 1.5rem;
  box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
  align-self: flex-end;
  margin-bottom: 0;
}

.swap-btn:hover {
  transform: rotate(180deg) scale(1.1);
  box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
}

.swap-btn:active {
  transform: rotate(180deg) scale(0.95);
}

.result-section {
  margin: 2rem 0;
  text-align: center;
  padding: 1.5rem;
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.05), rgba(118, 75, 162, 0.05));
  border-radius: 1rem;
  border: 1px solid var(--border-color);
}

.msg {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text-dark);
  margin: 0;
  word-wrap: break-word;
}

.exchange-info {
  font-size: 0.9rem;
  color: var(--text-light);
  margin-top: 0.5rem;
  min-height: 1.2rem;
}

.convert-btn {
  width: 100%;
  height: 3.2rem;
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  color: white;
  font-size: 1.1rem;
  font-weight: 600;
  border: none;
  outline: none;
  border-radius: 0.75rem;
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

.convert-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 25px rgba(102, 126, 234, 0.4);
}

.convert-btn:active {
  transform: translateY(0);
}

.convert-btn:disabled {
  opacity: 0.7;
  cursor: not-allowed;
  transform: none;
}

.convert-btn i {
  transition: transform 0.3s ease;
}

.convert-btn:hover i {
  transform: rotate(180deg);
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    padding: 2rem;
    margin: 1rem;
    width: 95%;
  }

  .header h1 {
    font-size: 1.6rem;
  }

  .header i {
    font-size: 2rem;
  }

  .dropdown {
    flex-direction: column;
    gap: 1.5rem;
    align-items: stretch;
  }

  .currency-box {
    width: 100%;
    min-width: unset;
  }

  .swap-btn {
    width: 2.8rem;
    height: 2.8rem;
    margin: -0.75rem auto;
    align-self: center;
  }

  .msg {
    font-size: 1.2rem;
  }

  .convert-btn {
    height: 2.8rem;
    font-size: 1rem;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 1.5rem;
    border-radius: 1rem;
  }

  .header {
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
  }

  .header h1 {
    font-size: 1.4rem;
  }

  .header i {
    font-size: 1.8rem;
  }

  .header .subtitle {
    font-size: 0.85rem;
  }

  #amountInput,
  .convert-btn,
  .swap-btn {
    height: 2.6rem;
  }

  .msg {
    font-size: 1.1rem;
  }

  .select img {
    width: 1.8rem;
  }

  .result-section {
    padding: 1rem;
  }
}

/* Loading state */
.loading {
  pointer-events: none;
  opacity: 0.7;
}