* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.container {
  background: white;
  border-radius: 12px;
  box-shadow: 0 10px 40px rgba(0,0,0,0.2);
  max-width: 600px;
  width: 100%;
  overflow: hidden;
}

.header {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 20px;
  text-align: center;
}

.header h1 {
  font-size: 24px;
  font-weight: 600;
  margin-bottom: 8px;
}

.user-info-header {
  font-size: 13px;
  opacity: 0.9;
  font-weight: 400;
}

.content {
  padding: 30px;
}

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

.form-group label {
  display: block;
  margin-bottom: 8px;
  color: #333;
  font-weight: 500;
  font-size: 14px;
}

input[type="text"],
input[type="email"],
input[type="password"] {
  width: 100%;
  padding: 12px 15px;
  border: 2px solid #e0e0e0;
  border-radius: 8px;
  font-size: 15px;
  transition: border-color 0.3s;
}

input[type="text"]:focus,
input[type="email"]:focus,
input[type="password"]:focus {
  outline: none;
  border-color: #667eea;
}

.btn {
  padding: 12px 24px;
  border: none;
  border-radius: 8px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s;
  width: 100%;
  margin-top: 10px;
}

.btn-primary {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
  background: #f5f5f5;
  color: #333;
}

.btn-secondary:hover {
  background: #e0e0e0;
}

.btn-danger {
  background: #f44336;
  color: white;
}

.btn-danger:hover {
  background: #d32f2f;
}

.btn-small {
  padding: 8px 16px;
  font-size: 13px;
}

/* Tab Navigation */
.tabs {
  display: flex;
  border-bottom: 2px solid #e0e0e0;
  background: #fafafa;
}

.tab-btn {
  flex: 1;
  padding: 15px;
  border: none;
  background: transparent;
  color: #666;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s;
  border-bottom: 3px solid transparent;
}

.tab-btn span {
  margin-right: 5px;
}

.tab-btn:hover {
  background: #f0f0f0;
  color: #333;
}

.tab-btn.active {
  color: #667eea;
  border-bottom-color: #667eea;
  background: white;
}

.tab-content {
  display: block;
}

.tab-content.hidden {
  display: none;
}

/* Chat Area */
.chat-header {
  padding: 15px;
  background: #f5f5f5;
  border-radius: 8px;
  margin-bottom: 15px;
}

.chat-header h3 {
  font-size: 16px;
  color: #333;
  font-weight: 600;
}

/* DM Chat Header */
.dm-chat-header {
  display: flex;
  align-items: center;
  gap: 12px;
}

.back-btn {
  background: white;
  border: 2px solid #e0e0e0;
  color: #667eea;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  font-size: 20px;
  font-weight: bold;
  cursor: pointer;
  transition: all 0.3s;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.back-btn:hover {
  background: #667eea;
  color: white;
  border-color: #667eea;
}

.dm-chat-info {
  flex: 1;
}

.dm-chat-info h3 {
  font-size: 16px;
  color: #333;
  font-weight: 600;
}

#messages,
#dmMessages {
  height: 350px;
  overflow-y: auto;
  border: 2px solid #e0e0e0;
  border-radius: 8px;
  padding: 15px;
  margin-bottom: 15px;
  background: #fafafa;
}

.message {
  padding: 10px 12px;
  margin-bottom: 10px;
  border-radius: 8px;
  background: white;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
  word-wrap: break-word;
}

.message .username {
  font-weight: 600;
  color: #667eea;
  margin-right: 8px;
}

.message .text {
  color: #333;
}

.message .time {
  font-size: 11px;
  color: #999;
  margin-left: 8px;
}

.input-group {
  display: flex;
  gap: 10px;
}

.input-group input {
  flex: 1;
}

.input-group button {
  width: auto;
  padding: 12px 24px;
  margin: 0;
}

/* DM Placeholder */
.dm-placeholder {
  text-align: center;
  padding: 60px 30px;
}

.placeholder-icon {
  font-size: 64px;
  margin-bottom: 20px;
  opacity: 0.5;
}

.dm-placeholder h3 {
  font-size: 20px;
  color: #333;
  margin-bottom: 10px;
}

.dm-placeholder p {
  color: #666;
  margin-bottom: 25px;
  font-size: 14px;
}

/* Modal */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 20px;
}

.modal.hidden {
  display: none;
}

.modal-content {
  background: white;
  border-radius: 12px;
  max-width: 500px;
  width: 100%;
  max-height: 80vh;
  overflow: hidden;
  box-shadow: 0 20px 60px rgba(0,0,0,0.3);
  animation: modalSlideIn 0.3s ease;
}

@keyframes modalSlideIn {
  from {
    transform: translateY(-50px);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

.modal-header {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.modal-header h2 {
  font-size: 20px;
  font-weight: 600;
}

.close-btn {
  background: none;
  border: none;
  color: white;
  font-size: 32px;
  cursor: pointer;
  line-height: 1;
  padding: 0;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  transition: background 0.3s;
}

.close-btn:hover {
  background: rgba(255, 255, 255, 0.2);
}

.modal-body {
  padding: 20px;
  max-height: calc(80vh - 80px);
  overflow-y: auto;
}

/* User List */
.user-list {
  margin-top: 15px;
}

.user-item {
  display: flex;
  align-items: center;
  padding: 12px 15px;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.3s;
  border: 2px solid transparent;
  margin-bottom: 8px;
}

.user-item:hover {
  background: #f5f5f5;
  border-color: #667eea;
}

.user-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 600;
  font-size: 18px;
  margin-right: 12px;
  flex-shrink: 0;
}

.user-details {
  flex: 1;
}

.user-username {
  font-weight: 600;
  color: #333;
  font-size: 15px;
}

.user-email {
  font-size: 12px;
  color: #999;
  margin-top: 2px;
}

.no-users {
  text-align: center;
  padding: 40px 20px;
  color: #999;
  font-size: 14px;
}

/* Footer */
.chat-footer {
  padding: 15px 30px;
  background: #fafafa;
  border-top: 1px solid #e0e0e0;
  text-align: center;
}

.hidden {
  display: none;
}

.error {
  color: #f44336;
  font-size: 13px;
  margin-top: 5px;
}

.info {
  background: #e3f2fd;
  color: #1976d2;
  padding: 12px;
  border-radius: 8px;
  margin-bottom: 20px;
  font-size: 14px;
}

/* Loading Spinner */
.spinner {
  border: 3px solid #f3f3f3;
  border-top: 3px solid #667eea;
  border-radius: 50%;
  width: 30px;
  height: 30px;
  animation: spin 1s linear infinite;
  margin: 20px auto;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

/* Responsive */
@media (max-width: 600px) {
  .content {
    padding: 20px;
  }
  
  #messages,
  #dmMessages {
    height: 300px;
  }
  
  .tab-btn {
    font-size: 13px;
    padding: 12px;
  }
  
  .dm-placeholder {
    padding: 40px 20px;
  }
  
  .modal-content {
    max-height: 90vh;
  }
}