* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Poppins', sans-serif;
  background: radial-gradient(circle at top left, #141E30, #243B55);
  color: #fff;
  padding: 20px;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

main {
  max-width: 900px;
  width: 100%;
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  animation: fadeIn 0.8s ease-out;
}

main > div {
  flex: 1 1 350px;
  background: rgba(255, 255, 255, 0.08);
  backdrop-filter: blur(12px);
  border-radius: 20px;
  padding: 25px;
  border: 1px solid rgba(255, 255, 255, 0.15);
  box-shadow: 0 8px 25px rgba(0,0,0,0.3);
  animation: slideUp 0.8s ease-out;
}
#pay {
  font-family: 'Poppins', sans-serif;
  font-size: 2.4rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 20px;
  letter-spacing: 1px;
  background: linear-gradient(90deg, #ffd700, #ffb347); /* Gold tones */
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  text-shadow: 0 3px 8px rgba(255, 215, 0, 0.4);
}



.bill-input p {
  font-weight: 600;
  margin-bottom: 8px;
  color: #FFD369;
  letter-spacing: 0.5px;
}

/* Input Container */
.input-container {
  background: rgba(255, 255, 255, 0.08);
  border-radius: 10px;
  display: flex;
  align-items: center;
  padding-left: 10px;
  font-size: 18px;
  border: 1px solid rgba(255,255,255,0.15);
  transition: all 0.25s ease;
}

.input-container:focus-within {
  border-color: #FFD369;
  box-shadow: 0 0 10px #FFD36955;
}

.input-container input {
  border: none;
  outline: none;
  width: 100%;
  padding: 12px;
  font-size: inherit;
  background: transparent;
  color: white;
}

/* Tip Buttons */
.tip-container {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-bottom: 15px;
}

.tip {
  background: linear-gradient(135deg, #FF512F, #F09819);
  border-radius: 8px;
  padding: 12px;
  font-weight: 600;
  font-size: 15px;
  color: white;
  border: none;
  cursor: pointer;
  transition: all 0.2s ease;
}

.tip:hover {
  transform: translateY(-3px) scale(1.03);
  box-shadow: 0 5px 15px rgba(255, 162, 0, 0.4);
}

.tip.selected {
  outline: 3px solid #FFD369;
}

/* Disabled state */
.tip-container.disabled,
.generate-bill-btn:disabled,
input:disabled,
.reset-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Gray Inputs */
.gray-input {
  background: rgba(255, 255, 255, 0.08);
  border: none;
  outline: none;
  font-size: 16px;
  padding: 10px;
  width: 100%;
  border-radius: 8px;
  margin-bottom: 12px;
  color: white;
}

/* Buttons */
.generate-bill-btn,
.reset-btn {
  width: 100%;
  padding: 14px;
  border: none;
  border-radius: 10px;
  font-weight: 600;
  font-size: 16px;
  color: white;
  background: linear-gradient(135deg, #00F260, #0575E6);
  cursor: pointer;
  transition: all 0.2s ease;
}

.generate-bill-btn:hover,
.reset-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0px 4px 15px rgba(0,255,160,0.4);
}

/* Bill Output */
.bill-output {
  background: rgba(0, 0, 0, 0.3);
  backdrop-filter: blur(14px);
  border-radius: 16px;
  padding: 25px;
  display: flex;
  flex-direction: column;
  gap: 28px;
  border: 1px solid rgba(255,255,255,0.1);
}

.bill-output p {
  font-weight: 700;
  font-size: 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.bill-output p span {
  font-size: 1.5rem;
  color: #FFD369;
}

/* Remove number spinners */
input[type=number]::-webkit-inner-spin-button,
input[type=number]::-webkit-outer-spin-button {
  -webkit-appearance: none;
  appearance: none;
  margin: 0;
}

/* Animations */
@keyframes fadeIn {
  from { opacity: 0; transform: scale(0.97); }
  to { opacity: 1; transform: scale(1); }
}

@keyframes slideUp {
  from { transform: translateY(20px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}

/* Responsive */
@media(max-width: 600px) {
  main {
    flex-direction: column;
  }
}