/* Bad Form Page - Mobile First */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
  background: #fafafa;
  color: #333;
  line-height: 1.7;
  font-size: 15px;
}

a {
  color: #666;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 16px;
}

/* Header */
.header {
  margin-bottom: 24px;
}

.back {
  font-size: 0.85rem;
  margin-bottom: 12px;
}

.header h1 {
  font-size: 1.5rem;
  font-weight: 600;
  color: #333;
  margin-bottom: 4px;
}

.subtitle {
  font-size: 0.9rem;
  color: #777;
}

/* Intro */
.intro {
  background: #fff;
  padding: 16px;
  border-radius: 10px;
  margin-bottom: 28px;
  border: 1px solid #ddd;
}

.intro p {
  margin-bottom: 8px;
}

.intro p:last-child {
  margin-bottom: 0;
}

/* Section */
.section {
  background: #fff;
  padding: 20px;
  border-radius: 10px;
  margin-bottom: 24px;
}

.section h2 {
  font-size: 1.1rem;
  font-weight: 600;
  color: #444;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid #eee;
}

/* Bad Form */
.bad-form {
  background: #fff5f5;
  border: 1px solid #f3caca;
  padding: 14px;
  border-radius: 8px;
  margin: 12px 0;
}

/* Good Form */
.good-form {
  background: #f5fff7;
  border: 1px solid #c8e6c9;
  padding: 14px;
  border-radius: 8px;
  margin: 12px 0;
}

/* Labels */
.label {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 4px;
  margin-bottom: 10px;
}

.label.bad {
  background: #ffcdd2;
  color: #c62828;
}

.label.good {
  background: #c8e6c9;
  color: #2e7d32;
}

.form-label {
  font-size: 0.85rem;
  font-weight: 500;
  color: #555;
  margin-bottom: 6px;
}

.form-group {
  margin-bottom: 12px;
}

.form-group:last-child {
  margin-bottom: 0;
}

.form-row {
  display: flex;
  align-items: center;
  gap: 4px;
  flex-wrap: nowrap;
}

.form-row input {
  max-width: 80px;
  width: auto;
  flex: 0 0 auto;
}

/* Input */
input[type="text"],
input[type="email"],
input[type="tel"],
input[type="password"] {
  width: 100%;
  padding: 10px 12px;
  font-size: 16px;
  border: 1px solid #ccc;
  border-radius: 6px;
  background: #fff;
}

input:focus {
  outline: none;
  border-color: #888;
}

.error-msg {
  font-size: 0.8rem;
  color: #c62828;
  margin-top: 6px;
}

.hint {
  font-size: 0.8rem;
  color: #666;
  margin-top: 6px;
}

/* Explanation */
.explanation {
  margin-top: 16px;
  padding: 12px;
  background: #f9f9f9;
  border-radius: 6px;
  font-size: 0.9rem;
  color: #555;
}

.explanation p {
  margin-bottom: 8px;
}

.explanation p:last-child {
  margin-bottom: 0;
}

.explanation ul {
  margin: 8px 0 0 20px;
}

.explanation li {
  margin-bottom: 4px;
}

/* Principle */
.principle {
  background: #fff;
  padding: 20px;
  border-radius: 10px;
  margin: 32px 0;
  border: 2px solid #ddd;
}

.principle h2 {
  font-size: 1rem;
  font-weight: 600;
  color: #444;
  margin-bottom: 12px;
}

.principle ul {
  list-style: none;
}

.principle li {
  padding: 8px 0;
  border-bottom: 1px solid #eee;
  font-size: 0.9rem;
}

.principle li:last-child {
  border-bottom: none;
}

/* Footer */
.footer {
  text-align: center;
  padding: 24px 16px;
  font-size: 0.8rem;
  color: #999;
  border-top: 1px solid #e0e0e0;
}

.footer p {
  margin-bottom: 8px;
}

.footer a {
  color: #666;
}

/* Responsive */
@media screen and (min-width: 640px) {
  .container {
    padding: 24px;
  }
  
  .section {
    padding: 24px;
  }
  
  .header h1 {
    font-size: 1.75rem;
  }
}