* {
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  margin: 0;
  padding: 16px;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.container {
  width: 100%;
  max-width: 500px;
  background: #fff;
  padding: 30px 20px;
  border-radius: 12px;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
}

h1 {
  margin: 0 0 5px 0;
  color: #333;
  font-size: 28px;
  text-align: center;
}

.subtitle {
  text-align: center;
  color: #666;
  margin: 0 0 30px 0;
  font-size: 14px;
}

.form-group {
  margin-bottom: 20px;
  display: flex;
  flex-direction: column;
}

label {
  font-weight: 500;
  color: #333;
  margin-bottom: 8px;
  font-size: 14px;
}

input[type="text"],
input[type="tel"],
input[type="file"],
select {
  padding: 12px;
  border: 2px solid #e0e0e0;
  border-radius: 6px;
  font-size: 16px;
  font-family: inherit;
  transition: border-color 0.3s;
  -webkit-appearance: none;
  appearance: none;
}

input[type="text"]:focus,
input[type="tel"]:focus,
input[type="file"]:focus,
select:focus {
  outline: none;
  border-color: #667eea;
  box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

input[type="file"] {
  padding: 10px;
  cursor: pointer;
}

button {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  border: none;
  padding: 14px 24px;
  border-radius: 6px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
  margin-top: 10px;
  min-height: 48px;
}

button:hover {
  transform: translateY(-2px);
  box-shadow: 0 5px 20px rgba(102, 126, 234, 0.4);
}

button:active {
  transform: translateY(0);
}

button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

#result {
  margin-top: 20px;
  padding: 15px;
  border-radius: 6px;
  text-align: center;
  font-weight: 500;
  min-height: 20px;
  display: none;
  font-size: 14px;
  word-wrap: break-word;
}

#result:not(:empty) {
  display: block;
}

#result[style*="color: green"] {
  background: #d4edda;
  border: 1px solid #c3e6cb;
  color: #155724;
}

#result[style*="color: red"] {
  background: #f8d7da;
  border: 1px solid #f5c6cb;
  color: #721c24;
}

/* Tablet and larger screens */
@media (min-width: 768px) {
  .container {
    padding: 40px;
  }

  h1 {
    font-size: 32px;
  }

  input[type="text"],
  input[type="tel"],
  input[type="file"],
  select {
    padding: 10px 12px;
    font-size: 14px;
  }

  button {
    padding: 12px 24px;
    min-height: auto;
  }
}

/* Large screens */
@media (min-width: 1024px) {
  body {
    padding: 20px;
  }

  .container {
    max-width: 600px;
  }
}