* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: #f4f5f7;
  color: #1a1a1a;
}
.screen { min-height: 100vh; }

#login-screen {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}
.login-box {
  width: 100%;
  max-width: 360px;
  background: white;
  padding: 28px 24px;
  border-radius: 14px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.08);
}
.login-box h1 { font-size: 20px; margin-bottom: 20px; text-align: center; }
.login-box input {
  width: 100%;
  padding: 12px;
  margin-bottom: 12px;
  border: 1px solid #ddd;
  border-radius: 8px;
  font-size: 16px;
}
.login-box button, .action-btn {
  width: 100%;
  padding: 13px;
  background: #d32f2f;
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
}
.error { color: #d32f2f; font-size: 14px; margin-top: 8px; }

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 16px;
  background: white;
  border-bottom: 1px solid #eee;
  position: sticky;
  top: 0;
  z-index: 10;
}
.link-btn { background: none; border: none; color: #666; font-size: 14px; }

.tabs {
  display: flex;
  background: white;
  border-bottom: 1px solid #eee;
}
.tab-btn {
  flex: 1;
  padding: 14px 0;
  background: none;
  border: none;
  font-size: 15px;
  font-weight: 600;
  color: #888;
  border-bottom: 3px solid transparent;
}
.tab-btn.active { color: #d32f2f; border-bottom-color: #d32f2f; }

main { padding: 16px; max-width: 480px; margin: 0 auto; }

.card {
  background: white;
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 14px;
  box-shadow: 0 1px 4px rgba(0,0,0,0.06);
}

label { display: block; font-size: 13px; color: #666; margin-bottom: 4px; margin-top: 10px; }
input, select {
  width: 100%;
  padding: 11px;
  border: 1px solid #ddd;
  border-radius: 8px;
  font-size: 16px;
}
button.secondary {
  background: white;
  color: #d32f2f;
  border: 1px solid #d32f2f;
  padding: 11px;
  border-radius: 8px;
  font-size: 15px;
  width: 100%;
  margin-top: 8px;
}
.action-btn { margin-top: 16px; }
.action-btn:disabled { background: #ccc; }

#scanner-box { width: 100%; margin-top: 10px; border-radius: 8px; overflow: hidden; }

.product-result {
  margin-top: 12px;
  padding: 12px;
  background: #fafafa;
  border-radius: 8px;
  border: 1px solid #eee;
}
.product-result .pname { font-weight: 600; }
.product-result .pmeta { font-size: 13px; color: #777; margin-top: 2px; }
.search-list { margin-top: 8px; }
.search-item {
  padding: 10px;
  border: 1px solid #eee;
  border-radius: 8px;
  margin-bottom: 6px;
  cursor: pointer;
}
.search-item:active { background: #f0f0f0; }

.msg { margin-top: 12px; padding: 10px; border-radius: 8px; font-size: 14px; }
.msg.success { background: #e6f4ea; color: #1e7e34; }
.msg.error { background: #fdecea; color: #c62828; }

.diff-pos { color: #1e7e34; font-weight: 600; }
.diff-neg { color: #c62828; font-weight: 600; }
.diff-zero { color: #666; font-weight: 600; }