:root {
  --bg: #f4f6f8;
  --panel: #ffffff;
  --text: #1f2933;
  --muted: #667085;
  --border: #d7dde5;
  --primary: #1a5fb4;
  --primary-dark: #154f95;
  --success: #17803a;
  --warning: #9a5b00;
  --error: #b42318;
  --shadow: 0 12px 30px rgba(15, 23, 42, 0.08);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111827;
    --panel: #182231;
    --text: #f2f4f7;
    --muted: #b8c0cc;
    --border: #344054;
    --primary: #7db4ff;
    --primary-dark: #5fa3ff;
    --shadow: 0 12px 30px rgba(0, 0, 0, 0.25);
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.app-shell {
  width: min(1180px, calc(100% - 32px));
  margin: 32px auto;
}

.app-header,
.app-footer {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: center;
}

.eyebrow {
  margin: 0 0 6px;
  color: var(--primary);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  font-size: 12px;
}

h1, h2 { margin: 0; }

h1 { font-size: 34px; }
h2 { font-size: 18px; margin-bottom: 18px; }

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

.version-badge {
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 8px 12px;
  color: var(--muted);
  background: var(--panel);
}

.grid {
  display: grid;
  grid-template-columns: 420px 1fr;
  gap: 22px;
  margin-top: 28px;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 18px;
  box-shadow: var(--shadow);
}

.form-panel { padding: 22px; }
.preview-panel { padding: 22px; }

label {
  display: block;
  margin: 14px 0 6px;
  font-weight: 700;
  font-size: 13px;
}

.required { color: var(--error); }

input, select {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 11px;
  font-size: 14px;
  background: var(--panel);
  color: var(--text);
}

input:focus, select:focus {
  outline: 2px solid color-mix(in srgb, var(--primary), transparent 72%);
  border-color: var(--primary);
}

.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 16px;
}

button, .file-button {
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--panel);
  color: var(--text);
  padding: 10px 13px;
  font-weight: 700;
  cursor: pointer;
  font-size: 14px;
}

button.primary {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

button.primary:hover { background: var(--primary-dark); }
button:disabled { opacity: .45; cursor: not-allowed; }

.hidden-file { display: none; }

.validation-box {
  margin-top: 14px;
  padding: 11px 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  color: var(--muted);
  font-size: 13px;
}

.validation-box.ok {
  color: var(--success);
  border-color: color-mix(in srgb, var(--success), transparent 55%);
}

.validation-box ul { margin: 0; padding-left: 18px; }
.validation-box .error { color: var(--error); }
.validation-box .warning { color: var(--warning); }

.instructions-box {
  margin-top: 18px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: color-mix(in srgb, var(--panel), var(--bg) 18%);
  font-size: 13px;
}

.instructions-box summary {
  cursor: pointer;
  padding: 12px 13px;
  font-weight: 700;
  color: var(--primary);
}

.instructions-box[open] summary {
  border-bottom: 1px solid var(--border);
}

.instructions-box ol {
  margin: 12px 16px 12px 30px;
  padding: 0;
  color: var(--text);
}

.instructions-box li {
  margin: 7px 0;
}

.instructions-box code {
  font-family: Consolas, Monaco, monospace;
  font-size: 12px;
  background: color-mix(in srgb, var(--border), transparent 55%);
  border-radius: 5px;
  padding: 1px 4px;
}

.instructions-note {
  margin: 12px 13px 14px;
  padding: 10px 11px;
  border-left: 3px solid var(--primary);
  background: color-mix(in srgb, var(--primary), transparent 90%);
  color: var(--text);
  border-radius: 8px;
}

.preview-header {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
  margin-bottom: 18px;
}

.copy-status {
  min-height: 18px;
  font-size: 13px;
  color: var(--success);
  font-weight: 700;
}
.copy-status.error { color: var(--error); }

.preview-canvas {
  min-height: 330px;
  background: #fff;
  color: #222;
  border: 1px solid #e4e7ec;
  border-radius: 14px;
  padding: 28px;
  overflow: auto;
}

.signature-preview { display: inline-block; }

.hint {
  margin: 14px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.app-footer {
  margin-top: 18px;
  color: var(--muted);
  font-size: 12px;
  flex-wrap: wrap;
}

@media (max-width: 900px) {
  .grid { grid-template-columns: 1fr; }
  .two-col { grid-template-columns: 1fr; }
  .app-header { align-items: flex-start; flex-direction: column; }
}