:root {
  --primary-color: #0078ff;
  --primary-hover: #005fcc;
  --bg-color: #fafafa;
  --card-bg: #ffffff;
  --text-main: #333333;
  --text-sub: #666666;
  --border-radius: 8px;
  --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-hover: 0 8px 15px rgba(0, 0, 0, 0.15);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-main);
  margin: 0;
  padding: 0;
  line-height: 1.6;
  -webkit-text-size-adjust: 100%;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 20px;
}

h1 {
  font-size: 24px;
  margin-bottom: 20px;
  text-align: center;
  color: #222;
}

h2 {
  font-size: 20px;
  margin-top: 25px;
  margin-bottom: 15px;
}

p {
  margin-bottom: 15px;
}

/* Card Layout for Index */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
  margin-top: 20px;
}

.tool-card {
  background: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 20px;
  box-shadow: var(--shadow);
  text-decoration: none;
  color: var(--text-main);
  transition: transform 0.2s, box-shadow 0.2s;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  /* Enhance touch target */
  min-height: 100px;
}

.tool-card:active {
  transform: scale(0.98);
}

@media (min-width: 600px) {
  .tool-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
  }
}

.tool-icon {
  font-size: 32px;
  margin-bottom: 12px;
}

.tool-title {
  font-size: 18px;
  font-weight: bold;
  margin-bottom: 8px;
  color: var(--primary-color);
}

.tool-desc {
  font-size: 14px;
  color: var(--text-sub);
  line-height: 1.5;
}

/* Back Link */
.back-link-container {
  margin-bottom: 15px;
}

.back-link {
  display: inline-flex;
  align-items: center;
  text-decoration: none;
  color: var(--primary-color);
  font-weight: 500;
  padding: 8px 0;
  /* Touch friendly */
}

/* Form Elements */
input[type="number"],
input[type="text"],
select {
  padding: 12px;
  border: 1px solid #ddd;
  border-radius: 4px;
  font-size: 16px;
  /* Prevents auto-zoom on iOS */
  width: 100%;
  box-sizing: border-box;
  margin-bottom: 10px;
}

button {
  background-color: var(--primary-color);
  color: white;
  border: none;
  padding: 14px 20px;
  /* Larger touch area */
  border-radius: var(--border-radius);
  cursor: pointer;
  font-size: 16px;
  width: 100%;
  font-weight: bold;
  margin-top: 10px;
  transition: background-color 0.2s;
}

button:active {
  background-color: var(--primary-hover);
  transform: translateY(1px);
}

/* Common Components */
.input-box {
  background: #fff;
  padding: 20px;
  margin-bottom: 20px;
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.result-box {
  background: #fff;
  padding: 20px;
  border-radius: 8px;
  box-shadow: var(--shadow);
  margin-top: 20px;
}

table {
  width: 100%;
  border-collapse: collapse;
  background: #fff;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: var(--shadow);
  margin-bottom: 20px;
}

th,
td {
  padding: 12px 10px;
  text-align: center;
  border-bottom: 1px solid #eee;
  font-size: 14px;
}

th {
  background-color: #f0f0f0;
  font-weight: 600;
}

/* Mobile Specific Adjustments */
@media (max-width: 600px) {
  .container {
    padding: 16px;
  }

  h1 {
    font-size: 22px;
  }

  .tool-grid {
    grid-template-columns: 1fr;
    /* Single column on mobile */
  }

  /* Table scroll if wide */
  .table-container {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  th,
  td {
    padding: 10px 5px;
    font-size: 13px;
  }
}