:root {
  --bg: #f4f4f9;
  --text: #222;
  --form-bg: #ffffff;
  --border-color: #ccc;
  --primary: #007bff;
  --danger: #dc3545;
  --success: #28a745;
  --radius: 8px;
  --transition-speed: 0.3s;
}

[data-theme="dark"] {
  --bg: #121212;
  --text: #eee;
  --form-bg: #1e1e1e;
  --border-color: #555;
  --primary: #58a6ff;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  background: var(--bg);
  color: var(--text);
  margin: 0;
  padding: 20px;
  transition: background-color var(--transition-speed), color var(--transition-speed);
}

.container {
  max-width: 600px;
  margin: auto;
  background: var(--form-bg);
  padding: 2rem;
  border-radius: var(--radius);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  transition: background-color var(--transition-speed);
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 1rem;
  margin-bottom: 1rem;
}

h1 {
  margin: 0;
}

label {
  display: block;
  margin: 15px 0 5px;
  font-weight: bold;
}

.input-wrap {
  position: relative;
}

input[type="text"],
input[type="email"],
input[type="tel"],
input[type="password"],
input[type="url"],
input[type="date"] {
  width: 100%;
  padding: 12px;
  border-radius: var(--radius);
  border: 1px solid var(--border-color);
  background-color: var(--bg);
  color: var(--text);
  box-sizing: border-box;
  transition: border-color var(--transition-speed), box-shadow var(--transition-speed);
}

input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25);
}

input.invalid {
  border-color: var(--danger);
}

input.invalid:focus {
  box-shadow: 0 0 0 3px rgba(220, 53, 69, 0.25);
}

input.valid {
  border-color: var(--success);
}

input.valid:focus {
  box-shadow: 0 0 0 3px rgba(40, 167, 69, 0.25);
}

#togglePassword {
  position: absolute;
  right: 10px;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  cursor: pointer;
  padding: 5px;
  font-size: 1.2rem;
}

#themeToggle {
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
}

button[type="submit"] {
  width: 100%;
  padding: 12px 15px;
  border: none;
  border-radius: var(--radius);
  background: var(--primary);
  color: white;
  margin-top: 20px;
  font-size: 1rem;
  font-weight: bold;
  cursor: pointer;
  transition: background-color var(--transition-speed), opacity var(--transition-speed);
  display: flex;
  align-items: center;
  justify-content: center;
}

button:disabled {
  background: #888;
  cursor: not-allowed;
  opacity: 0.7;
}

.error {
  color: var(--danger);
  font-size: 0.875rem;
  min-height: 1.2em;
  margin-top: 4px;
}

.progress {
  height: 8px;
  background: #ddd;
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 20px;
}

#progressBar {
  height: 100%;
  width: 0%;
  background: var(--success);
  border-radius: var(--radius);
  transition: width 0.4s ease-in-out;
}

.strength {
  margin-top: 10px;
}

#meter {
  height: 8px;
  background: #eee;
  border-radius: var(--radius);
  overflow: hidden;
}

#meterFill {
  display: block;
  height: 100%;
  width: 0%;
  background: var(--danger);
  border-radius: var(--radius);
  transition: width 0.4s ease-in-out, background-color 0.4s ease-in-out;
}

.form-group-checkbox {
  display: flex;
  align-items: center;
  margin-top: 15px;
}

.form-group-checkbox input {
  margin-right: 10px;
}

.form-group-checkbox label {
  margin: 0;
  font-weight: normal;
}

#formMessage {
  text-align: center;
  margin-top: 1rem;
  font-weight: bold;
}

/* --- ADDED FOR PHASE 4 --- */
.form-links {
  text-align: center;
  margin-top: 1rem;
}

.form-links a {
  color: var(--primary);
  text-decoration: none;
  font-size: 0.875rem;
}

.form-links a:hover {
  text-decoration: underline;
}

.spinner {
  display: inline-block;
  width: 16px;
  height: 16px;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  border-top-color: #fff;
  animation: spin 1s ease-in-out infinite;
  margin-right: 8px;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}