body {
  font-family: system-ui, sans-serif;
  background: #0f1220;
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.calculator {
  background: #181c3a;
  padding: 24px;
  border-radius: 12px;
  width: 280px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.4);
}

h2 {
  margin-bottom: 16px;
  font-size: 18px;
  text-align: center;
}

label {
  font-size: 13px;
  opacity: 0.8;
}

input, select {
  width: 100%;
  padding: 10px;
  margin: 6px 0 14px;
  border-radius: 8px;
  border: none;
  outline: none;
  font-size: 14px;
}

.result {
  text-align: center;
  font-size: 16px;
  margin-top: 10px;
}

#frames {
  font-weight: bold;
  color: #4fd1ff;
}

/* Chrome, Edge, Safari */
input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

/* Firefox */
input[type="number"] {
  -moz-appearance: textfield;
}

input,
select {
  width: 100%;
  height: 44px;              /* force same height */
  padding: 0 14px;           /* same horizontal padding */
  border-radius: 10px;
  border: none;
  outline: none;
  font-size: 15px;
  box-sizing: border-box;    /* 🔴 THIS IS CRITICAL */
}

.copy-btn {
  margin-left: 8px;
  padding: 4px 10px;
  font-size: 12px;
  border-radius: 6px;
  border: none;
  background: #2b6cff;
  color: #fff;
  cursor: pointer;
  transition: background 0.2s ease;
}

.copy-btn:hover {
  background: #1f54cc;
}

.copy-btn.copied {
  background: #22c55e;
}