:root {
  color-scheme: light;
  --bg: #f3f4f6;
  --panel: #fafafa;
  --ink: #1f2933;
  --muted: #6b7280;
  --accent: #2f4e70;
  --accent-2: #2d6a6f;
  --key: #e5e7eb;
  --key-strong: #cbd5e1;
  --key-ghost: #d5dbe3;
  --key-text: #1f2933;
  --shadow: 0 18px 40px rgba(46, 36, 27, 0.18);
  --radius: 18px;
  --radius-sm: 12px;
  --font-display: "Noto Serif KR", serif;
  --font-body: "Noto Sans KR", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: var(--font-body);
  background: radial-gradient(circle at top left, #f8fafc 0%, #f3f4f6 45%, #e5e7eb 100%);
  color: var(--ink);
  min-height: 100vh;
}

.app {
  max-width: 1100px;
  margin: 0 auto;
  padding: 48px 20px 72px;
  display: grid;
  gap: 32px;
}

.hero {
  display: grid;
  gap: 16px;
  align-items: end;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.eyebrow {
  text-transform: uppercase;
  font-weight: 600;
  letter-spacing: 0.28em;
  font-size: 0.72rem;
  margin: 0 0 10px;
  color: var(--accent-2);
}

h1 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 3vw, 3rem);
  margin: 0 0 12px;
}

.sub {
  color: var(--muted);
  margin: 0;
  line-height: 1.6;
}

.status {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: flex-start;
}

.chip {
  background: #fff;
  border-radius: 999px;
  padding: 8px 14px;
  font-size: 0.85rem;
  border: 1px solid rgba(46, 36, 27, 0.1);
  box-shadow: 0 6px 12px rgba(46, 36, 27, 0.1);
}

.chip.subtle {
  background: #e5e7eb;
  color: var(--muted);
  border-color: transparent;
}

.panel {
  background: var(--panel);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
  display: grid;
  gap: 28px;
}

.display {
  background: #fff;
  border-radius: var(--radius-sm);
  padding: 20px;
  border: 1px solid rgba(31, 41, 51, 0.1);
  display: grid;
  gap: 12px;
}

.label {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--muted);
}

#display {
  width: 100%;
  font-size: clamp(1.3rem, 2vw, 1.8rem);
  border: none;
  outline: none;
  font-family: var(--font-display);
  color: var(--ink);
  background: transparent;
}

.meta-row {
  display: grid;
  gap: 6px;
}

.preview {
  color: var(--accent-2);
  font-weight: 600;
}

.message {
  color: #b13c2d;
  font-size: 0.9rem;
  min-height: 1.1em;
}

.x-input {
  border: 1px solid rgba(31, 41, 51, 0.15);
  border-radius: var(--radius-sm);
  padding: 10px 12px;
  font-size: 1rem;
  font-family: var(--font-body);
  background: #fff;
  color: var(--ink);
}

.controls {
  display: grid;
  gap: 18px;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

.control-group {
  display: grid;
  gap: 10px;
}

.segmented {
  background: #e5e7eb;
  border-radius: 999px;
  padding: 6px;
  display: inline-flex;
  gap: 6px;
}

.seg {
  border: none;
  background: transparent;
  padding: 8px 16px;
  border-radius: 999px;
  font-weight: 600;
  color: var(--muted);
  cursor: pointer;
  font-family: var(--font-body);
}

.seg.active {
  background: var(--accent-2);
  color: #fff;
}

.keypad {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(6, minmax(0, 1fr));
}

.key {
  border: none;
  padding: 18px 12px;
  border-radius: var(--radius-sm);
  font-size: 1.05rem;
  font-weight: 600;
  background: var(--key);
  color: var(--key-text);
  cursor: pointer;
  box-shadow: 0 10px 16px rgba(46, 36, 27, 0.12);
  transition: transform 0.12s ease, box-shadow 0.12s ease;
  font-family: var(--font-body);
}

.key:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 18px rgba(46, 36, 27, 0.16);
}

.key:active,
.key.is-pressed {
  transform: translateY(1px);
  box-shadow: 0 6px 12px rgba(46, 36, 27, 0.12);
  background: var(--key-strong);
}

.key-ghost {
  background: var(--key-ghost);
  color: var(--accent-2);
}

.key-accent {
  background: var(--accent);
  color: #fff;
}

.key-accent:active,
.key-accent.is-pressed {
  background: #1f3b59;
}

.key-wide {
  grid-column: span 2;
}

@media (max-width: 860px) {
  .panel {
    padding: 24px;
  }

  .keypad {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .key-wide {
    grid-column: span 2;
  }
}

@media (max-width: 520px) {
  .app {
    padding: 28px 16px 40px;
  }

  .panel {
    padding: 20px;
  }

  .key {
    padding: 16px 10px;
  }
}