*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #f5f5f5;
  --bg-card: #fff;
  --text: #111;
  --text-2: #555;
  --text-3: #888;
  --border: #e0e0e0;
  --border-focus: #2563eb;
  --error: #dc2626;
  --success: #16a34a;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --font: system-ui, -apple-system, 'Segoe UI', sans-serif;
  --radius: 8px;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

nav {
  padding: 20px 40px;
}
nav a { font-size: 0.8125rem; color: var(--text-3); text-decoration: none; }
nav a:hover { color: var(--text); }

main {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.form-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 36px 40px;
  width: 100%;
  max-width: 400px;
  box-shadow: 0 4px 24px rgba(0,0,0,0.06);
}

.form-header { margin-bottom: 28px; }
.form-header h1 { font-size: 1.375rem; letter-spacing: -0.02em; margin-bottom: 4px; }
.form-header p { font-size: 0.875rem; color: var(--text-3); }

/* Fields */
.field { margin-bottom: 18px; }

label {
  display: block;
  font-size: 0.8125rem;
  font-weight: 500;
  margin-bottom: 6px;
  color: var(--text);
}
.label-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 6px;
}
.label-row label { margin-bottom: 0; }
.forgot-link { font-size: 0.78rem; color: var(--accent); text-decoration: none; }
.forgot-link:hover { text-decoration: underline; }

input[type="email"],
input[type="password"],
input[type="text"] {
  width: 100%;
  padding: 10px 12px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  font-family: inherit;
  font-size: 0.9375rem;
  color: var(--text);
  background: var(--bg-card);
  transition: border-color 0.15s;
  outline: none;
}
input:focus { border-color: var(--border-focus); box-shadow: 0 0 0 3px rgba(37,99,235,0.1); }
input:focus-visible { outline: none; }

.field.error input { border-color: var(--error); }
.field.error input:focus { box-shadow: 0 0 0 3px rgba(220,38,38,0.1); }
.field.success input { border-color: var(--success); }
.field.success input:focus { box-shadow: 0 0 0 3px rgba(22,163,74,0.1); }

/* Password wrapper */
.input-wrap { position: relative; }
.input-wrap input { padding-right: 44px; }
.pw-toggle {
  position: absolute;
  right: 10px;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-3);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 4px;
  border-radius: 4px;
  transition: color 0.12s;
}
.pw-toggle:hover { color: var(--text); }
.pw-toggle:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* Field messages */
.field-message {
  font-size: 0.78rem;
  margin-top: 5px;
  min-height: 18px;
  transition: opacity 0.15s;
}
.field.error .field-message { color: var(--error); }
.field.success .field-message { color: var(--success); }

/* Submit button */
.submit-btn {
  width: 100%;
  padding: 11px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  font-family: inherit;
  font-size: 0.9375rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin-top: 8px;
  position: relative;
}
.submit-btn:hover:not(:disabled) { background: var(--accent-hover); }
.submit-btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.submit-btn:disabled { opacity: 0.6; cursor: not-allowed; }

.btn-spinner {
  display: none;
  width: 16px;
  height: 16px;
  border: 2px solid rgba(255,255,255,0.3);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}
.submit-btn.loading .btn-text { opacity: 0; position: absolute; }
.submit-btn.loading .btn-spinner { display: block; }

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

/* Divider */
.divider {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 20px 0;
  color: var(--text-3);
  font-size: 0.78rem;
}
.divider::before,
.divider::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

/* Social button */
.social-btn {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 10px;
  background: var(--bg-card);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  font-family: inherit;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text);
  cursor: pointer;
  transition: border-color 0.12s, background 0.12s;
}
.social-btn:hover { border-color: #bbb; background: #fafafa; }
.social-btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* Sign up link */
.signup-link {
  text-align: center;
  font-size: 0.8125rem;
  color: var(--text-3);
  margin-top: 20px;
}
.signup-link a { color: var(--accent); text-decoration: none; font-weight: 500; }
.signup-link a:hover { text-decoration: underline; }

@media (max-width: 480px) {
  .form-card { padding: 28px 24px; border: none; box-shadow: none; background: none; }
}