:root {
  --bg: #f4f7fb;
  --card: #ffffff;
  --line: #d9e2ef;
  --text: #17212f;
  --accent: #0e7a6d;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Yu Gothic UI", "Hiragino Kaku Gothic ProN", sans-serif;
  background: linear-gradient(145deg, #f7fafc 0%, #eaf1f8 100%);
  color: var(--text);
}

.container {
  max-width: 720px;
  margin: 24px auto;
  padding: 0 16px 24px;
}

h1 {
  margin: 0 0 16px;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 14px;
}

label {
  display: block;
  font-weight: 600;
  margin: 8px 0 6px;
}

input,
select {
  width: 100%;
  border-radius: 8px;
  border: 1px solid #c8d5e6;
  padding: 10px;
  font-size: 15px;
}

button {
  width: 100%;
  border-radius: 8px;
  border: 1px solid #c8d5e6;
  background: #fff;
  color: var(--text);
  font-weight: 600;
  padding: 10px;
  font-size: 15px;
  margin: 4px 0;
  cursor: pointer;
}

button:hover {
  background: #f3f7fc;
}

.primary-btn {
  background: var(--accent);
  color: #fff;
  border: none;
  font-weight: 700;
  margin: 6px 0 14px;
}

.primary-btn:hover {
  filter: brightness(0.95);
  background: var(--accent);
}

.grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.keypad {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 8px;
  margin-top: 8px;
}

.keypad-btn {
  margin: 0;
  grid-column: span 2;
}

.keypad-btn-action {
  grid-column: span 3;
}

.hidden {
  display: none;
}

.result ul {
  margin: 6px 0 0;
  padding-left: 20px;
}

@media (max-width: 600px) {
  .grid {
    grid-template-columns: 1fr;
  }
}