:root {
  --bg: #0f172a;
  --card-bg: #1e293b;
  --text: #f1f5f9;
  --text-muted: #94a3b8;
  --accent: #10b981;
  --accent-hover: #34d399;
  --border: #334155;
  --focus-ring: rgba(16, 185, 129, 0.3);
  --input-bg: #0f172a;
  --radius: 12px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

.container {
  background: var(--card-bg);
  max-width: 480px;
  width: 100%;
  padding: 2.5rem;
  border-radius: var(--radius);
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
}

.header {
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

h1 {
  font-size: 2rem;
  font-weight: 700;
  text-align: center;
  color: var(--accent);
}

.settings-btn {
  position: absolute;
  right: 0;
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 1.4rem;
  cursor: pointer;
  padding: 0.25rem;
  transition: color 0.2s;
}

.settings-btn:hover,
.settings-btn.active {
  color: var(--accent);
}

.subtitle {
  text-align: center;
  color: var(--text-muted);
  margin-bottom: 2rem;
  font-size: 1rem;
}

.settings-panel {
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  transition: max-height 0.3s ease, opacity 0.3s ease, margin 0.3s ease;
  margin-bottom: 0;
}

.settings-panel.open {
  max-height: 200px;
  opacity: 1;
  margin-bottom: 0.25rem;
}

label {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 0.375rem;
  color: var(--text);
}

input[type="text"] {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 2px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  margin-bottom: 1.25rem;
  background: var(--input-bg);
  color: var(--text);
  transition: border-color 0.2s, box-shadow 0.2s;
}

input[type="text"]:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--focus-ring);
}

.note {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-align: center;
  margin-bottom: 1rem;
}

.result {
  text-align: center;
  opacity: 0;
  max-height: 0;
  margin-top: 0;
  overflow: hidden;
  transition: opacity 0.35s ease, max-height 0.35s ease, margin-top 0.35s ease;
}

.result.visible {
  opacity: 1;
  max-height: 200px;
  margin-top: 2rem;
}

.result-time {
  font-size: 2rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.02em;
}

.result-detail {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-top: 0.5rem;
}

.guide {
  border-top: 1px solid var(--border);
  opacity: 0;
  max-height: 0;
  margin-top: 0;
  padding-top: 0;
  overflow: hidden;
  transition: opacity 0.35s ease, max-height 0.35s ease, margin-top 0.35s ease, padding-top 0.35s ease;
}

.guide.visible {
  opacity: 1;
  max-height: 300px;
  margin-top: 2rem;
  padding-top: 1.25rem;
}

.guide-title {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  text-align: center;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.75rem;
}

.guide-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.5rem;
}

.guide-item {
  text-align: center;
  padding: 0.5rem 0.25rem;
  background: var(--input-bg);
  border-radius: 8px;
}

.guide-item .label {
  font-size: 0.7rem;
  color: var(--text-muted);
  margin-bottom: 0.2rem;
}

.guide-item .value {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--accent);
}

@media (max-width: 480px) {
  .container {
    padding: 1.5rem;
  }

  h1 {
    font-size: 1.6rem;
  }

  .result-time {
    font-size: 1.6rem;
  }
}