* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  background: #f4f4f6;
  color: #18181b;
}
header {
  height: 58px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 22px;
  background: #fff;
  border-bottom: 1px solid #e4e4e7;
  position: sticky;
  top: 0;
  z-index: 10;
}
.brand { font-weight: 800; text-decoration: none; color: #111; }
nav a, a { color: #2563eb; }
main { max-width: 1180px; margin: 26px auto; padding: 0 16px; }
.card {
  background: #fff;
  border: 1px solid #e4e4e7;
  border-radius: 18px;
  padding: 22px;
  margin-bottom: 18px;
  box-shadow: 0 8px 26px rgba(0,0,0,.05);
}
h1 { margin: 0 0 18px; font-size: 26px; }
h2 { margin: 0 0 14px; font-size: 20px; }
label { display: grid; gap: 8px; font-weight: 650; }
input, select {
  padding: 11px 12px;
  border: 1px solid #d4d4d8;
  border-radius: 12px;
  font: inherit;
  background: #fff;
}
button, .button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  padding: 10px 16px;
  border: 0;
  border-radius: 12px;
  background: #18181b;
  color: #fff;
  font: inherit;
  font-weight: 750;
  cursor: pointer;
  text-decoration: none;
}
.upload, .settings {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  align-items: end;
}
.preview-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 18px;
  margin-bottom: 18px;
}
.preview-card {
  display: grid;
  gap: 10px;
  padding: 12px;
  border: 2px solid #e4e4e7;
  border-radius: 16px;
  cursor: pointer;
}
.preview-card:has(input:checked) {
  border-color: #18181b;
  background: #fafafa;
}
.preview-card img {
  width: 100%;
  height: 300px;
  object-fit: contain;
  background: #f5f5f5;
  border-radius: 12px;
}
.pdf-list { display: grid; gap: 8px; }
.pdf-row {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 12px;
  padding: 10px;
  border: 1px solid #eee;
  border-radius: 12px;
}
.merge-row {
  display: flex;
  gap: 10px;
  margin-top: 14px;
  flex-wrap: wrap;
}
.merge-row input, select { min-width: 260px; flex: 1; }
.muted { color: #71717a; }
.error { color: #b91c1c; font-weight: 700; }
.login-page {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 20px;
}
.login { width: min(420px, 100%); }
.login h1 { text-align: center; }
.login form, .login { display: grid; gap: 14px; }

.preview-open {
  display: block;
  border-radius: 12px;
  outline: none;
}
.preview-open:hover img {
  filter: contrast(1.04);
}
.small { font-size: 13px; }
.sig-check {
  display: grid;
  grid-template-columns: minmax(260px, 1fr) minmax(260px, 420px);
  gap: 18px;
  align-items: center;
  padding: 14px;
  margin-bottom: 18px;
  border: 1px solid #e4e4e7;
  border-radius: 16px;
  background: #fafafa;
}
.sig-check h2 { margin-top: 0; }
.sig-preview-link {
  display: grid;
  gap: 8px;
  text-align: center;
  font-weight: 700;
  text-decoration: none;
}
.sig-preview-link img {
  width: 100%;
  max-height: 220px;
  object-fit: contain;
  background: #fff;
  border: 1px dashed #d4d4d8;
  border-radius: 12px;
  padding: 10px;
}
@media (max-width: 720px) {
  .sig-check { grid-template-columns: 1fr; }
  .preview-card img { height: 240px; }
}