:root {
  --bg-color: #1e1e1e;
  --text-color: #f2f2f2;
  --accent-color: #4a4a4a;
  --border-color: #333333;
  --unit-bg: #2a2a2a;
  --btn-bg: #4a4a4a;
  --btn-text: #ffffff;
}

[data-theme="light"] {
  --bg-color: #f2f2f2;
  --text-color: #1e1e1e;
  --accent-color: #4a4a4a;
  --border-color: #cccccc;
  --unit-bg: #e8e8e8;
  --btn-bg: #333333;
  --btn-text: #ffffff;
}

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

html {
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
  text-align: center;
  padding: 2rem;
  width: 100%;
  max-width: 600px;
}

header {
  margin-bottom: 3rem;
}

header h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  letter-spacing: -0.02em;
}

header p {
  font-size: 1rem;
  color: #888;
}

.timer {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 3rem;
  flex-wrap: wrap;
}

.unit {
  display: flex;
  flex-direction: column;
  align-items: center;
  background: var(--unit-bg);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.5rem 1rem;
  min-width: 100px;
}

.value {
  font-size: 2.5rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  line-height: 1;
  margin-bottom: 0.5rem;
}

.label {
  font-size: 0.875rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: #888;
}

.actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin-bottom: 2rem;
}

.btn {
  border: none;
  border-radius: 8px;
  padding: 0.75rem 1.5rem;
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
  background: var(--btn-bg);
  color: var(--btn-text);
}

.btn:hover {
  opacity: 0.9;
  transform: translateY(-1px);
}

.btn.ghost {
  background: transparent;
  border: 1px solid var(--border-color);
}

.btn.ghost:hover {
  background: var(--border-color);
}

.date-info {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border-color);
}

.date-info p {
  font-size: 0.9rem;
  color: #888;
}

footer {
  margin-top: 3rem;
  font-size: 0.8rem;
  color: #666;
}

@media (max-width: 480px) {
  html {
    font-size: 14px;
  }

  .timer {
    gap: 0.5rem;
  }

  .unit {
    min-width: 80px;
    padding: 1rem 0.5rem;
  }

  .value {
    font-size: 2rem;
  }
}

@media (max-width: 360px) {
  .timer {
    flex-direction: column;
    gap: 0.75rem;
  }

  .unit {
    min-width: unset;
    width: 100%;
  }
}