/* Reset & Base */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: #ffffff;
  color: #1a1a1a;
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

/* Header */
header {
  background-color: #1e40af;
  color: #ffffff;
  padding: 1.5rem 0;
  text-align: center;
}

header h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.tagline {
  font-size: 0.95rem;
  opacity: 0.9;
  margin-top: 0.25rem;
}

/* Main */
main {
  flex: 1;
  padding: 2rem 0 3rem;
}

.tool-card {
  background-color: #ffffff;
  border: 1px solid #e5e7eb;
  border-radius: 8px;
  padding: 1.75rem;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
}

label {
  display: block;
  font-weight: 600;
  font-size: 0.9rem;
  color: #374151;
  margin-bottom: 0.5rem;
}

textarea {
  width: 100%;
  padding: 0.875rem 1rem;
  border: 1px solid #d1d5db;
  border-radius: 6px;
  font-family: "SF Mono", "Fira Code", "Cascadia Code", Consolas, monospace;
  font-size: 0.9rem;
  line-height: 1.5;
  resize: vertical;
  background-color: #f9fafb;
  color: #111827;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

textarea:focus {
  outline: none;
  border-color: #2563eb;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
  background-color: #ffffff;
}

textarea[readonly] {
  background-color: #f3f4f6;
  color: #1f2937;
}

.char-count {
  font-size: 0.8rem;
  color: #6b7280;
  margin-top: 0.35rem;
  margin-bottom: 1.25rem;
  text-align: right;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.65rem 1.25rem;
  font-size: 0.95rem;
  font-weight: 600;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  transition: background-color