:root {
  --vb-primary: #4f46e5;
  --vb-secondary: #0ea5e9;
  --vb-accent: #e0e7ff;
  --bg-main: #f8fafc;
  --card-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
  --border-radius: 16px;
  --primary-text: #1e293b;
  --secondary-text: #64748b;
  --white: #ffffff;
  --error: #ef4444;
  --success: #10b981;
}

body {
  margin: 0;
  padding: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: var(--bg-main);
  color: var(--primary-text);
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 60px 20px;
}

.header {
  text-align: center;
  margin-bottom: 50px;
}

.header h1 {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--vb-primary);
  margin-bottom: 10px;
}

.header p {
  font-size: 1.1rem;
  color: var(--secondary-text);
  font-weight: 500;
}

.main-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 30px;
}

@media (min-width: 768px) {
  .main-grid {
    grid-template-columns: 1.2fr 1fr;
  }
}

.card {
  background: var(--white);
  border-radius: var(--border-radius);
  padding: 32px;
  box-shadow: var(--card-shadow);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  border: 1px solid #f1f5f9;
}

.card h3 {
  margin-top: 0;
  font-size: 1.25rem;
  color: var(--vb-primary);
  margin-bottom: 24px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.card h3::before {
  content: '';
  width: 4px;
  height: 20px;
  background: var(--vb-secondary);
  border-radius: 2px;
}

.input-group {
  margin-bottom: 20px;
}

.input-group label {
  display: block;
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--secondary-text);
  margin-bottom: 8px;
}

.input-group input {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid #e2e8f0;
  border-radius: 10px;
  font-size: 1rem;
  color: var(--primary-text);
  transition: border-color 0.2s, box-shadow 0.2s;
  box-sizing: border-box;
  background: #f8fafc;
}

.input-group input:focus {
  outline: none;
  border-color: var(--vb-primary);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
  background: var(--white);
}

.dropzone {
  border: 2px dashed #cbd5e1;
  border-radius: var(--border-radius);
  padding: 50px 20px;
  text-align: center;
  cursor: pointer;
  background: #f8fafc;
  transition: all 0.3s ease;
}

.dropzone:hover, .dropzone.active {
  border-color: var(--vb-primary);
  background: #eff6ff;
}

.dropzone p {
  color: var(--secondary-text);
  margin: 0;
}

.contact-preview {
  margin-top: 24px;
  padding-top: 20px;
  border-top: 1px solid #f1f5f9;
}

.contact-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 15px;
  max-height: 150px;
  overflow-y: auto;
  padding: 5px;
}

.chip {
  background: var(--vb-accent);
  color: var(--vb-primary);
  padding: 6px 12px;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 700;
}

.action-bar {
  grid-column: 1 / -1;
  text-align: center;
  margin-top: 20px;
}

.send-button {
  background-color: var(--vb-primary);
  color: var(--white);
  border: none;
  padding: 16px 60px;
  font-size: 1.1rem;
  font-weight: 700;
  border-radius: 50px;
  cursor: pointer;
  box-shadow: 0 4px 15px rgba(79, 70, 229, 0.3);
  transition: all 0.2s ease;
}

.send-button:hover:not(:disabled) {
  background-color: #4338ca;
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(79, 70, 229, 0.4);
}

.send-button:active {
  transform: translateY(0);
}

.secondary-button {
  background-color: transparent;
  color: var(--vb-primary);
  border: 2px solid var(--vb-primary);
  padding: 10px 20px;
  font-size: 0.9rem;
  font-weight: 700;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.2s ease;
  width: 100%;
  margin-top: 10px;
}

.secondary-button:hover {
  background-color: var(--vb-accent);
}

.secondary-button.saved {
  background-color: var(--success);
  color: white;
  border-color: var(--success);
}

.send-button:disabled {
  background-color: #cbd5e1;
  cursor: not-allowed;
  box-shadow: none;
}

.results-section {
  grid-column: 1 / -1;
  margin-top: 40px;
}

.stats-container {
  display: flex;
  gap: 20px;
  margin-bottom: 24px;
}

.stat-box {
  flex: 1;
  padding: 20px;
  border-radius: var(--border-radius);
  text-align: center;
}

.stat-box.success { background: #ecfdf5; border: 1px solid #a7f3d0; }
.stat-box.failure { background: #fef2f2; border: 1px solid #fecaca; }

.stat-box h4 {
  margin: 0;
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 5px;
  color: var(--secondary-text);
}

.stat-box .count {
  font-size: 2rem;
  font-weight: 800;
}

.log-container {
  border: 1px solid #e2e8f0;
  border-radius: 12px;
  overflow: hidden;
}

.log-header {
  background: #f8fafc;
  padding: 12px 20px;
  font-weight: 700;
  font-size: 0.9rem;
  border-bottom: 1px solid #e2e8f0;
  display: flex;
  justify-content: space-between;
}

.log-scroll {
  max-height: 400px;
  overflow-y: auto;
}

.log-row {
  padding: 12px 20px;
  border-bottom: 1px solid #f1f5f9;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.95rem;
}

.log-row:last-child {
  border-bottom: none;
}

.status-badge {
  padding: 4px 12px;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
}

.status-badge.success { background: var(--success); color: white; }
.status-badge.failure { background: var(--error); color: white; }

.error-detail {
  display: block;
  font-size: 0.8rem;
  color: var(--error);
  margin-top: 4px;
}