/* ===== BASIC RESET ===== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* ===== GLOBAL ===== */
body {
  font-family: 'Poppins', sans-serif;
  background: #ffffff;
  color: #000;
  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: 100vh;
}

/* ===== HEADER ===== */
header {
  text-align: center;
  padding: 1.5rem 1rem;
  width: 100%;
  border-bottom: 1px solid #eee;
}

header h1 {
  font-size: 1.8rem;
  font-weight: 700;
}

header p {
  font-size: 1rem;
  color: #555;
  margin-top: 0.4rem;
}

/* ===== CALCULATOR ===== */
.calculator {
  width: 100%;
  max-width: 420px;
  background: #fff;
  margin: 1.5rem auto;
  padding: 1.2rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

label {
  font-weight: 600;
  font-size: 0.95rem;
}

input, select {
  width: 100%;
  padding: 10px;
  font-size: 1rem;
  border: 1px solid #ccc;
  border-radius: 6px;
  background: #fafafa;
  outline: none;
  transition: 0.2s;
}

input:focus, select:focus {
  border-color: #000;
  background: #fff;
}

/* ===== BUTTONS ===== */
.buttons {
  display: flex;
  flex-direction: column;
  gap: 0.7rem;
}

.btn {
  width: 100%;
  padding: 10px;
  font-size: 1rem;
  border-radius: 6px;
  border: 1px solid #000;
  background: transparent;
  cursor: pointer;
  transition: 0.3s;
  font-weight: 600;
}

.btn.primary {
  background: #000;
  color: #fff;
}

.btn:hover {
  opacity: 0.8;
}

/* ===== RESULT ===== */
.result {
  text-align: center;
  font-weight: 600;
  margin-top: 1rem;
  padding: 10px;
  background: #f7f7f7;
  border-radius: 6px;
  min-height: 40px;
}

/* ===== FOOTER ===== */
footer {
  margin-top: auto;
  padding: 1rem;
  text-align: center;
  font-size: 0.9rem;
  color: #555;
  width: 100%;
  border-top: 1px solid #eee;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 600px) {
  header h1 { font-size: 1.5rem; }
  .calculator { padding: 1rem; margin: 1rem; }
  input, select, button { font-size: 0.95rem; }
}

@media (max-width: 400px) {
  header h1 { font-size: 1.3rem; }
  .btn { font-size: 0.9rem; }
}