:root {
  --bg: #0f1115;
  --surface: #1a1d24;
  --surface-2: #22262f;
  --text: #f2f3f5;
  --text-dim: #9aa0ac;
  --accent: #6c8cff;
  --accent-dim: #3b4ba8;
  --bubble-user: #6c8cff;
  --bubble-bot: #22262f;
  --radius: 16px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

.screen {
  max-width: 480px;
  margin: 0 auto;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.hidden { display: none !important; }

/* Onboarding screen */
.onboarding-inner {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 24px 28px 48px;
  text-align: center;
}
.onboarding-icon {
  font-size: 40px;
  margin: 0 auto 12px;
}
.onboarding-inner h1 {
  margin: 0 0 8px;
  font-size: 26px;
}
.onboarding-inner > p {
  margin: 0 0 28px;
  color: var(--text-dim);
}
.onboarding-form {
  display: flex;
  flex-direction: column;
  gap: 8px;
  text-align: left;
}
.onboarding-form label {
  font-size: 13px;
  color: var(--text-dim);
  margin-top: 8px;
}
.onboarding-form input {
  background: var(--surface);
  border: 1px solid #2a2e38;
  border-radius: 12px;
  padding: 12px 14px;
  color: var(--text);
  font-size: 15px;
  outline: none;
}
.onboarding-form input:focus { border-color: var(--accent); }
#onboarding-submit {
  margin-top: 20px;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 999px;
  padding: 14px;
  font-weight: 600;
  font-size: 15px;
  cursor: pointer;
}
#onboarding-submit:disabled {
  background: var(--accent-dim);
  cursor: not-allowed;
}
.onboarding-note {
  margin: 14px 0 0;
  font-size: 12px;
  color: var(--text-dim);
  text-align: center;
}
.onboarding-note a { color: var(--accent); }

/* Topic screen */
.topic-header {
  padding: 48px 24px 16px;
  text-align: center;
}
.topic-header h1 {
  margin: 0 0 8px;
  font-size: 28px;
}
.topic-header p {
  margin: 0;
  color: var(--text-dim);
}

.card-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  padding: 20px 20px 40px;
}

.topic-card {
  background: var(--surface);
  border: 1px solid #2a2e38;
  border-radius: var(--radius);
  padding: 20px 14px;
  color: var(--text);
  text-align: left;
  display: flex;
  flex-direction: column;
  gap: 6px;
  cursor: pointer;
  transition: transform 0.15s ease, border-color 0.15s ease;
}
.topic-card:hover,
.topic-card:focus-visible {
  transform: translateY(-2px);
  border-color: var(--accent);
}
.topic-card:active { transform: translateY(0); }

.card-icon { font-size: 26px; }
.card-title { font-weight: 600; font-size: 15px; }
.card-sub { font-size: 12px; color: var(--text-dim); }

/* Chat screen */
.chat-header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px 16px;
  border-bottom: 1px solid #2a2e38;
  position: sticky;
  top: 0;
  background: var(--bg);
  z-index: 2;
}
.back-btn {
  background: none;
  border: none;
  color: var(--text);
  font-size: 20px;
  cursor: pointer;
  padding: 4px 8px;
}
.chat-header h2 {
  margin: 0;
  font-size: 17px;
}

.messages {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.msg {
  max-width: 78%;
  padding: 10px 14px;
  border-radius: 16px;
  font-size: 14px;
  line-height: 1.4;
  white-space: pre-wrap;
}
.msg.user {
  align-self: flex-end;
  background: var(--bubble-user);
  color: white;
  border-bottom-right-radius: 4px;
}
.msg.bot {
  align-self: flex-start;
  background: var(--bubble-bot);
  border-bottom-left-radius: 4px;
}
.msg.typing {
  color: var(--text-dim);
  font-style: italic;
}
.msg.error {
  align-self: center;
  background: #3a1f24;
  color: #ff9aa2;
  font-size: 13px;
}

.chat-form {
  display: flex;
  gap: 8px;
  padding: 12px 16px 20px;
  border-top: 1px solid #2a2e38;
  position: sticky;
  bottom: 0;
  background: var(--bg);
}

#chat-input {
  flex: 1;
  background: var(--surface);
  border: 1px solid #2a2e38;
  border-radius: 999px;
  padding: 12px 16px;
  color: var(--text);
  font-size: 14px;
  outline: none;
}
#chat-input:focus { border-color: var(--accent); }

#send-btn {
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 999px;
  padding: 0 20px;
  font-weight: 600;
  cursor: pointer;
}
#send-btn:disabled {
  background: var(--accent-dim);
  cursor: not-allowed;
}