/* ============ Reset & Variables ============ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #0f1117;
  --surface: #1a1d27;
  --surface-2: #22263a;
  --border: #2a2f45;
  --text: #e4e6f0;
  --text-muted: #8b90a8;
  --primary: #6366f1;
  --primary-hover: #818cf8;
  --primary-glow: rgba(99, 102, 241, 0.25);
  --success: #22c55e;
  --error: #ef4444;
  --warning: #f59e0b;
  --radius: 12px;
  --radius-lg: 16px;
  --transition: 0.2s ease;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ============ Header ============ */
.header {
  background: rgba(26, 29, 39, 0.8);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-content {
  max-width: 900px;
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 14px;
}

.logo-icon {
  font-size: 28px;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--primary), #a855f7);
  border-radius: var(--radius);
}

.logo h1 {
  font-size: 20px;
  font-weight: 700;
  letter-spacing: -0.3px;
}

.subtitle {
  font-size: 12px;
  color: var(--text-muted);
  font-weight: 400;
}

.status-badge {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  background: var(--surface-2);
  border-radius: 20px;
  font-size: 13px;
  font-weight: 500;
  color: var(--text-muted);
}

.status-badge.online { color: var(--success); }
.status-badge.online .status-dot { background: var(--success); box-shadow: 0 0 8px var(--success); }
.status-badge.offline { color: var(--error); }
.status-badge.offline .status-dot { background: var(--error); }

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--text-muted);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

/* ============ Main ============ */
.main {
  max-width: 900px;
  margin: 0 auto;
  padding: 32px 24px;
  position: relative;
}

/* ============ Upload Cards ============ */
.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-bottom: 28px;
}

.upload-card {
  background: var(--surface);
  border: 2px dashed var(--border);
  border-radius: var(--radius-lg);
  padding: 36px 24px;
  text-align: center;
  cursor: pointer;
  transition: all var(--transition);
  position: relative;
}

.upload-card:hover {
  border-color: var(--primary);
  background: var(--surface-2);
  transform: translateY(-2px);
}

.upload-card.has-file {
  border-color: var(--success);
  border-style: solid;
}

.upload-card.dragover {
  border-color: var(--primary);
  background: rgba(99, 102, 241, 0.08);
  transform: scale(1.02);
}

.upload-icon {
  font-size: 40px;
  margin-bottom: 12px;
}

.upload-card h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 6px;
}

.upload-card p {
  font-size: 13px;
  color: var(--text-muted);
}

.file-info {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 12px;
  padding: 8px 12px;
  background: var(--surface-2);
  border-radius: 8px;
  font-size: 13px;
}

.file-name {
  font-weight: 500;
  color: var(--text);
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.file-size {
  color: var(--text-muted);
  font-size: 12px;
}

.btn-remove {
  background: none;
  border: none;
  color: var(--error);
  cursor: pointer;
  font-size: 16px;
  padding: 2px 6px;
  border-radius: 4px;
  transition: background var(--transition);
}

.btn-remove:hover {
  background: rgba(239, 68, 68, 0.15);
}

.sig-preview {
  margin-top: 12px;
  max-width: 120px;
  max-height: 60px;
  border-radius: 6px;
  border: 1px solid var(--border);
}

/* ============ Config Section ============ */
.config-section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-bottom: 28px;
}

.section-title {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 20px;
}

.config-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-group label {
  font-size: 13px;
  font-weight: 500;
  color: var(--text);
}

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

.form-group input[type="text"],
.form-group input[type="number"] {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 14px;
  color: var(--text);
  font-size: 14px;
  font-family: var(--font);
  transition: border-color var(--transition);
}

.form-group input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-glow);
}

.form-group small {
  font-size: 11px;
  color: var(--text-muted);
}

.checkbox-group {
  justify-content: center;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  font-size: 14px;
}

.checkbox-label input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--primary);
  cursor: pointer;
}

/* ============ Button ============ */
.btn-sign {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  width: 100%;
  padding: 16px;
  background: linear-gradient(135deg, var(--primary), #a855f7);
  color: white;
  border: none;
  border-radius: var(--radius);
  font-size: 16px;
  font-weight: 600;
  font-family: var(--font);
  cursor: pointer;
  transition: all var(--transition);
  box-shadow: 0 4px 20px var(--primary-glow);
}

.btn-sign:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: 0 6px 30px var(--primary-glow);
}

.btn-sign:active:not(:disabled) {
  transform: translateY(0);
}

.btn-sign:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  box-shadow: none;
}

.btn-icon {
  font-size: 20px;
}

/* ============ Result ============ */
.result-section {
  margin-top: 28px;
}

.result-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  text-align: center;
}

.result-card.success {
  border-color: var(--success);
}

.result-card.error {
  border-color: var(--error);
}

.result-icon {
  font-size: 48px;
  margin-bottom: 12px;
}

.result-card h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 8px;
}

.result-card p {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 16px;
}

.result-meta {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 16px;
  font-size: 13px;
}

.result-meta span {
  color: var(--text-muted);
}

.result-meta strong {
  color: var(--text);
}

.btn-download {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  background: var(--success);
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 15px;
  font-weight: 600;
  font-family: var(--font);
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
}

.btn-download:hover {
  background: #16a34a;
  transform: translateY(-1px);
}

/* ============ Loading ============ */
.loading-overlay {
  position: fixed;
  inset: 0;
  background: rgba(15, 17, 23, 0.85);
  backdrop-filter: blur(8px);
  align-items: center;
  justify-content: center;
  z-index: 1000;
  display: none;
}

.loading-overlay.active {
  display: flex;
}

.loading-content {
  text-align: center;
}

.spinner {
  width: 48px;
  height: 48px;
  border: 3px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin: 0 auto 16px;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.loading-content p {
  font-size: 16px;
  font-weight: 500;
  margin-bottom: 4px;
}

.loading-content small {
  font-size: 13px;
  color: var(--text-muted);
}

/* ============ Responsive ============ */
@media (max-width: 640px) {
  .form-grid, .config-grid {
    grid-template-columns: 1fr;
  }
  .header-content {
    flex-direction: column;
    gap: 12px;
  }
}