/* =============================================
   Currency Converter - style.css
   Dark Navy Theme | SaaS Style | Pure CSS
   ============================================= */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

/* ---- CSS Reset & Base ---- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg-page:        #0d1117;
  --bg-card:        #161b22;
  --bg-input:       #1c2230;
  --bg-input-focus: #1e2739;
  --bg-btn:         #2563eb;
  --bg-btn-hover:   #1d4ed8;
  --bg-swap:        #1c2230;
  --bg-swap-hover:  #232e44;
  --bg-result:      #1a2436;

  --border:         #2a3447;
  --border-focus:   #2563eb;
  --border-result:  #2563eb;

  --text-primary:   #e6edf3;
  --text-secondary: #8b949e;
  --text-label:     #8b949e;
  --text-btn:       #ffffff;
  --text-result:    #e6edf3;
  --text-amount:    #2563eb;
  --text-error:     #f85149;
  --text-success:   #3fb950;

  --radius-card:    16px;
  --radius-input:   10px;
  --radius-btn:     10px;
  --radius-badge:   8px;

  --shadow-card: 0 4px 32px rgba(0, 0, 0, 0.45);
  --shadow-btn:  0 2px 8px rgba(37, 99, 235, 0.30);

  --transition: 0.2s ease;
}

html, body {
  height: 100%;
}

body {
  font-family: 'Inter', system-ui, sans-serif;
  background-color: var(--bg-page);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 24px 16px;
}

/* ---- Page Header ---- */
.page-header {
  text-align: center;
  margin-bottom: 32px;
}

.page-header .logo {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}

.page-header .logo-icon {
  width: 40px;
  height: 40px;
  background-color: var(--bg-btn);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
}

.page-header h1 {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.3px;
}

.page-header p {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-top: 4px;
}

/* ---- Card ---- */
.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  box-shadow: var(--shadow-card);
  width: 100%;
  max-width: 480px;
  padding: 36px 32px;
}

/* ---- Form Labels ---- */
.form-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 20px;
}

.form-group label {
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-label);
  text-transform: uppercase;
  letter-spacing: 0.6px;
}

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

.input-wrapper .currency-symbol {
  position: absolute;
  left: 14px;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-secondary);
  pointer-events: none;
  user-select: none;
}

input#amount {
  width: 100%;
  padding: 12px 14px 12px 36px;
  background-color: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-input);
  color: var(--text-primary);
  font-size: 1.1rem;
  font-weight: 600;
  font-family: inherit;
  outline: none;
  transition: border-color var(--transition), background-color var(--transition);
  -moz-appearance: textfield;
}

input#amount::-webkit-outer-spin-button,
input#amount::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

input#amount:focus {
  border-color: var(--border-focus);
  background-color: var(--bg-input-focus);
}

input#amount::placeholder {
  color: var(--text-secondary);
  font-weight: 400;
}

/* ---- Currency Row (From / Swap / To) ---- */
.currency-row {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: end;
  margin-bottom: 20px;
}

.currency-row .form-group {
  margin-bottom: 0;
}

/* ---- Select / Dropdown ---- */
select {
  width: 100%;
  padding: 12px 36px 12px 14px;
  background-color: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-input);
  color: var(--text-primary);
  font-size: 0.9rem;
  font-weight: 500;
  font-family: inherit;
  outline: none;
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='14' height='14' viewBox='0 0 24 24' fill='none' stroke='%238b949e' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  transition: border-color var(--transition), background-color var(--transition);
}

select:focus {
  border-color: var(--border-focus);
  background-color: var(--bg-input-focus);
}

select option {
  background-color: #1c2230;
  color: var(--text-primary);
}

/* ---- Swap Button ---- */
#swapBtn {
  width: 42px;
  height: 42px;
  background-color: var(--bg-swap);
  border: 1px solid var(--border);
  border-radius: var(--radius-btn);
  color: var(--text-secondary);
  font-size: 1.1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color var(--transition), color var(--transition), border-color var(--transition), transform 0.3s ease;
  flex-shrink: 0;
  margin-bottom: 0;
}

#swapBtn:hover {
  background-color: var(--bg-swap-hover);
  border-color: var(--border-focus);
  color: var(--text-primary);
  transform: rotate(180deg);
}

/* ---- Convert Button ---- */
#convertBtn {
  width: 100%;
  padding: 14px;
  background-color: var(--bg-btn);
  border: none;
  border-radius: var(--radius-btn);
  color: var(--text-btn);
  font-size: 0.95rem;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  letter-spacing: 0.2px;
  box-shadow: var(--shadow-btn);
  transition: background-color var(--transition), transform var(--transition), box-shadow var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}

#convertBtn:hover {
  background-color: var(--bg-btn-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(37, 99, 235, 0.40);
}

#convertBtn:active {
  transform: translateY(0);
  box-shadow: var(--shadow-btn);
}

#convertBtn:disabled {
  opacity: 0.65;
  cursor: not-allowed;
  transform: none;
}

/* ---- Loading Spinner ---- */
.spinner {
  width: 18px;
  height: 18px;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-top-color: #ffffff;
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
  display: none;
}

.spinner.active {
  display: block;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ---- Divider ---- */
.divider {
  height: 1px;
  background-color: var(--border);
  margin: 24px 0;
}

/* ---- Result Box ---- */
#resultBox {
  background-color: var(--bg-result);
  border: 1px solid var(--border-result);
  border-radius: var(--radius-badge);
  padding: 20px 22px;
  display: none;
  animation: fadeSlideIn 0.3s ease;
}

#resultBox.visible {
  display: block;
}

@keyframes fadeSlideIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.result-label {
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.6px;
  margin-bottom: 8px;
}

.result-main {
  font-size: 1.9rem;
  font-weight: 700;
  color: var(--text-result);
  letter-spacing: -0.5px;
  word-break: break-all;
  margin-bottom: 6px;
}

.result-main span.converted-amount {
  color: var(--text-amount);
}

.result-rate {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

/* ---- Error Message ---- */
#errorBox {
  background-color: rgba(248, 81, 73, 0.1);
  border: 1px solid rgba(248, 81, 73, 0.35);
  border-radius: var(--radius-badge);
  padding: 12px 16px;
  font-size: 0.85rem;
  color: var(--text-error);
  display: none;
  margin-top: 16px;
  animation: fadeSlideIn 0.25s ease;
}

#errorBox.visible {
  display: block;
}

/* ---- Footer ---- */
.page-footer {
  margin-top: 28px;
  font-size: 0.78rem;
  color: var(--text-secondary);
  text-align: center;
}

.page-footer a {
  color: var(--text-secondary);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-footer a:hover {
  color: var(--text-primary);
}

/* ---- Last Updated Badge ---- */
.rate-updated {
  font-size: 0.75rem;
  color: var(--text-secondary);
  text-align: right;
  margin-top: 10px;
}

.dot {
  display: inline-block;
  width: 7px;
  height: 7px;
  background-color: var(--text-success);
  border-radius: 50%;
  margin-right: 5px;
  vertical-align: middle;
}

/* ---- Responsive ---- */
@media (max-width: 520px) {
  .card {
    padding: 28px 20px;
  }

  .result-main {
    font-size: 1.5rem;
  }

  .page-header h1 {
    font-size: 1.35rem;
  }

  .currency-row {
    grid-template-columns: 1fr auto 1fr;
    gap: 8px;
  }

  #swapBtn {
    width: 38px;
    height: 38px;
    font-size: 1rem;
  }
}

@media (max-width: 360px) {
  .currency-row {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .swap-wrapper {
    text-align: center;
  }

  #swapBtn {
    width: 100%;
    height: 38px;
    border-radius: var(--radius-btn);
  }
}