:root {
  font-family: Inter, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --bg: #f3f6fb;
  --surface: #ffffff;
  --text: #0f172a;
  --muted: #5b6474;
  --primary: #2f6bff;
  --primary-hover: #2455d3;
  --border: #d7deea;
  --shadow: 0 10px 26px rgba(15, 23, 42, 0.08);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: radial-gradient(circle at top, #edf3ff 0%, var(--bg) 50%);
  color: var(--text);
}

.app {
  display: grid;
  gap: 14px;
  max-width: 760px;
  margin: 0 auto;
  padding: 18px 14px 22px;
}

h1, h2, h3 {
  margin: 0 0 10px;
}

h1 {
  font-size: 34px;
  line-height: 1.1;
  letter-spacing: -0.02em;
}

h2 {
  font-size: 20px;
}

p {
  margin: 8px 0;
}

#auth-state {
  color: var(--muted);
}

.help-box {
  border: 1px solid rgba(37, 99, 235, 0.35);
  background: rgba(37, 99, 235, 0.08);
  color: var(--text);
  border-radius: 12px;
  padding: 12px;
  line-height: 1.4;
}

.card {
  background: var(--surface);
  border: 1px solid rgba(47, 107, 255, 0.08);
  border-radius: 18px;
  padding: 18px;
  box-shadow: var(--shadow);
}

.inline {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.promo-row {
  margin-top: 8px;
}

.promo-row input {
  flex: 1 1 220px;
}

button {
  border: 0;
  border-radius: 12px;
  min-height: 44px;
  padding: 0 16px;
  margin-top: 8px;
  background: var(--primary);
  color: #fff;
  font-weight: 600;
  font-size: 18px;
  cursor: pointer;
  transition: background-color 0.2s ease, transform 0.1s ease;
}

button:hover {
  background: var(--primary-hover);
}

button:active {
  transform: translateY(1px);
}

input[type='text'] {
  border: 1px solid var(--border);
  background: #fff;
  color: var(--text);
  border-radius: 12px;
  min-height: 44px;
  padding: 0 14px;
  font-size: 18px;
}

input[type='checkbox'] {
  width: 18px;
  height: 18px;
}

a {
  color: var(--primary-hover);
}

.modal {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  display: grid;
  place-items: center;
}

.modal-content {
  max-width: 440px;
  background: #fff;
  border-radius: 16px;
  padding: 20px;
}

.hidden {
  display: none;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b1220;
    --surface: #0f172a;
    --text: #e5e7eb;
    --muted: #aeb7c6;
    --primary: #4c7eff;
    --primary-hover: #6f96ff;
    --border: #22314f;
    --shadow: 0 12px 30px rgba(2, 6, 23, 0.6);
  }

  body {
    background: radial-gradient(circle at top, #121d36 0%, var(--bg) 50%);
  }

  input[type='text'] {
    background: #0b1220;
  }
}