:root {
  --bg: #111111;
  --panel: #181818;
  --panel-alt: #1f1f1f;
  --border: #2a2a2a;
  --text: #f3f3f3;
  --muted: #a3a3a3;
  --accent: #d7d7d7;
  --accent-strong: #f5f5f5;
  --danger: #d1d1d1;
  --shadow: rgba(0, 0, 0, 0.35);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  font-family: Arial, Helvetica, sans-serif;
  background: var(--bg);
  color: var(--text);
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 24px;
}

button,
input,
select {
  font: inherit;
}

.app-shell {
  width: min(100%, 980px);
}

.page-header {
  margin-bottom: 16px;
}

.page-header h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 2.6rem);
  font-weight: 700;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.layout {
  display: grid;
  grid-template-columns: 1.25fr 0.75fr;
  gap: 20px;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  box-shadow: 0 8px 18px var(--shadow);
}

.form-panel {
  padding: 22px;
}

.result-panel {
  padding: 22px;
}

#calculator-form {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.field-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

label {
  font-size: 0.86rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

input,
select {
  width: 100%;
  min-height: 44px;
  padding: 10px 12px;
  background: var(--panel-alt);
  border: 1px solid var(--border);
  color: var(--text);
  outline: none;
}

input:focus,
select:focus {
  border-color: var(--accent);
}

.primary-button,
.secondary-button {
  border: 1px solid var(--border);
  min-height: 44px;
  padding: 10px 18px;
  cursor: pointer;
  transition: opacity 0.2s ease;
}

.primary-button {
  background: var(--accent);
  color: #111111;
  font-weight: 700;
}

.secondary-button {
  background: transparent;
  color: var(--text);
}

.primary-button:hover,
.secondary-button:hover {
  opacity: 0.9;
}

.result-panel h2 {
  margin: 0 0 18px;
  font-size: 1.5rem;
}

.stats {
  display: grid;
  gap: 12px;
}

.stat {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 0;
  border-bottom: 1px solid var(--border);
}

.stat span {
  color: var(--muted);
}

.stat strong {
  font-size: 0.98rem;
}

.timer-box {
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
}

#timer-display {
  font-size: clamp(2.2rem, 4vw, 3.2rem);
  font-weight: 700;
  text-align: center;
  letter-spacing: 0.04em;
  margin-bottom: 14px;
}

.timer-actions {
  display: flex;
  gap: 10px;
}

.timer-actions button {
  flex: 1;
}

@media (max-width: 760px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .field-row {
    grid-template-columns: 1fr;
  }
}