* {
  box-sizing: border-box;
}

:root {
  --bg-1: #eef4ff;
  --bg-2: #f7fbff;
  --card: #ffffff;
  --text: #1f2b40;
  --muted: #6b7280;
  --border: #d6e1f2;
  --focus: #3b82f6;
  --danger: #dc2626;
  --success: #15803d;
}

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, var(--bg-1), var(--bg-2));
  color: var(--text);
}

.card {
  width: min(500px, 92vw);
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 24px;
  box-shadow: 0 18px 42px rgba(31, 43, 64, 0.1);
}

h1 {
  margin: 0;
  font-size: clamp(1.5rem, 3vw, 2rem);
}

.subtitle {
  margin: 8px 0 18px;
  color: var(--muted);
}

.field {
  margin-bottom: 12px;
}

label {
  display: block;
  margin-bottom: 6px;
  font-weight: 600;
}

input[type="text"],
input[type="email"],
input[type="password"] {
  width: 100%;
  border: 1px solid #c7d6ee;
  border-radius: 10px;
  padding: 10px 12px;
  font: inherit;
  outline: none;
}

input:focus {
  border-color: var(--focus);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.16);
}

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

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

.checkbox-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 2px;
  font-weight: 500;
}

.checkbox-row input {
  width: 16px;
  height: 16px;
}

.error {
  min-height: 16px;
  color: var(--danger);
  display: block;
  margin-top: 5px;
  font-size: 0.82rem;
}

button {
  margin-top: 8px;
  border: 0;
  background: #2563eb;
  color: #fff;
  border-radius: 10px;
  padding: 10px 14px;
  font-weight: 600;
  cursor: pointer;
}

.success {
  min-height: 20px;
  color: var(--success);
  font-weight: 700;
  margin-top: 10px;
}