:root {
  /* Light theme variables */
  --bg-color: #f5f7fa;
  --card-bg: white;
  --text-primary: #1a202c;
  --text-secondary: #2d3748;
  --text-tertiary: #718096;
  --shadow-color: rgba(0, 0, 0, 0.05);
  --shadow-color-hover: rgba(0, 0, 0, 0.15);
  --heading-color: #1a365d;
}

.dark-theme {
  /* Dark theme variables */
  --bg-color: #1a202c;
  --card-bg: #2d3748;
  --text-primary: #f7fafc;
  --text-secondary: #e2e8f0;
  --text-tertiary: #a0aec0;
  --shadow-color: rgba(0, 0, 0, 0.2);
  --shadow-color-hover: rgba(0, 0, 0, 0.4);
  --heading-color: #90cdf4;
}

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

body {
  font-family: 'Inter', sans-serif;
  background-color: var(--bg-color);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  transition: background-color 0.3s ease, color 0.3s ease;
  padding: 2rem 0;
}

.container {
  width: 100%;
  max-width: 1200px;
  padding: 0 2rem;
}

.header {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  margin-top: 2rem;
  margin-bottom: 4rem;
  flex-wrap: wrap;
}

.format-toggle {
  display: flex;
  gap: 0.5rem;
  background-color: var(--card-bg);
  padding: 0.25rem;
  border-radius: 8px;
  box-shadow: 0 2px 4px var(--shadow-color);
}

.time-format-btn {
  border: none;
  background: none;
  padding: 0.5rem 1rem;
  border-radius: 6px;
  color: var(--text-secondary);
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.2s ease;
}

.time-format-btn:hover {
  color: var(--text-primary);
}

.time-format-btn.active {
  background-color: var(--bg-color);
  color: var(--text-primary);
  font-weight: 700;
}

h1 {
  text-align: center;
  font-weight: 300;
  color: var(--heading-color);
  font-size: 2.5rem;
  margin: 0;
}

.clock-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.clock-card {
  background-color: var(--card-bg);
  border-radius: 12px;
  padding: 1.5rem 2rem;
  box-shadow: 0 10px 25px var(--shadow-color);
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
  min-width: 280px;
}

.clock-card::before {
  display: none;
}

.location,
.time {
  position: static;
}

.clock-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 15px 30px var(--shadow-color-hover);
}

.location {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.timezone {
  font-size: 0.9rem;
  color: var(--text-tertiary);
  margin-bottom: 1rem;
  font-family: 'Space Mono', monospace;
}

.location::after {
  content: attr(data-daynight);
  font-size: 1.2rem;
  margin-left: auto;
}

.time {
  font-size: 2.5rem;
  font-family: 'Space Mono', monospace;
  font-weight: 300;
  color: var(--text-primary);
  letter-spacing: 0.5px;
  margin-bottom: 0.5rem;
  white-space: nowrap;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
  align-items: center;
}

.time-input {
  padding: 0.5rem;
  border: 1px solid var(--text-tertiary);
  border-radius: 4px;
  background: var(--card-bg);
  color: var(--text-primary);
  font-family: 'Space Mono', monospace;
  width: 120px;
}

.set-time-btn {
  padding: 0.5rem 1rem;
  background: var(--heading-color);
  color: var(--card-bg);
  border: none;
  border-radius: 4px;
  cursor: pointer;
  font-family: 'Inter', sans-serif;
  font-weight: 600;
  transition: opacity 0.2s ease;
}

.set-time-btn:hover {
  opacity: 0.9;
}
.date {
  font-size: 14px;
  color: var(--text-tertiary);
  font-family: 'Space Mono', monospace;
  letter-spacing: 0.5px;
}

@media (max-width: 768px) {
  .container {
    padding: 1rem;
  }

  h1 {
    font-size: 2rem;
  }

  .header {
    margin-top: 0px;
    margin-bottom: 2rem;
  }

  .time {
    font-size: 2.2rem;
    letter-spacing: 0;
  }

  .clock-card {
    padding: 1.25rem 1.5rem;
  }
}

.footer {
  text-align: center;
  margin-top: 3rem;
  padding: 1.5rem;
  color: var(--text-tertiary);
  font-size: 0.9rem;
}

.footer a {
  color: var(--heading-color);
  text-decoration: none;
  transition: opacity 0.2s ease;
}

.footer a:hover {
  opacity: 0.8;
}

.city-dropdown {
  padding: 10px 15px;
  font-size: 1rem;
  font-family: 'Inter', sans-serif;
  border: 2px solid #e0e0e0;
  border-radius: 8px;
  background-color: #ffffff;
  color: #333;
  cursor: pointer;
  transition: all 0.3s ease;
  width: 200px;
  appearance: none;
  background-image: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='currentColor' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
  background-repeat: no-repeat;
  background-position: right 10px center;
  background-size: 1em;
}

.city-dropdown:hover {
  border-color: #007bff;
}

.city-dropdown:focus {
  outline: none;
  border-color: #007bff;
  box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25);
}

.time-comparison {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 2rem;
}

.comparison-equals {
  font-size: 2rem;
  color: var(--text-secondary);
  margin: 0 1rem;
}

.time-display {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 1.5rem;
}

.time-card {
  background-color: var(--card-bg);
  border-radius: 12px;
  padding: 1.5rem;
  min-width: 280px;
  box-shadow: 0 10px 25px var(--shadow-color);
}

.time-card h2 {
  color: var(--text-secondary);
  font-size: 1.1rem;
  margin-bottom: 1rem;
}

.time-input-container {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.time-difference {
  text-align: center;
  color: var(--text-tertiary);
  font-size: 0.9rem;
  margin: 0 auto 2rem;
  max-width: fit-content;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.time-difference::before {
  content: "ℹ️";
  font-size: 1.1rem;
}

.city-select {
  position: relative;
  margin: 0;
}