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

body {
  font-family: var(--font-ui);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow: hidden;
}

/* Header */
.header {
  height: 60px;
  background-color: white;
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  padding: 0 var(--spacing-lg);
  box-shadow: var(--shadow-sm);
  position: relative;
  z-index: 10;
}

.logo {
  font-family: var(--font-logo);
  font-size: 24px;
  font-weight: 700;
  color: var(--accent-navy);
  letter-spacing: -0.5px;
}

/* Main container */
.container {
  display: flex;
  flex-direction: column;
  height: calc(100vh - 60px);
}

/* Conversation area */
.conversation-area {
  flex: 1;
  overflow-y: auto;
  padding: var(--spacing-lg);
  padding-bottom: var(--spacing-xl);
}

.conversation-area::-webkit-scrollbar {
  width: 6px;
}

.conversation-area::-webkit-scrollbar-track {
  background: transparent;
}

.conversation-area::-webkit-scrollbar-thumb {
  background: var(--border-medium);
  border-radius: 3px;
}

.conversation-area::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* Messages */
.message {
  margin-bottom: var(--spacing-lg);
  animation: slideIn 0.3s var(--transition-normal);
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.message-user {
  display: flex;
  justify-content: flex-end;
}

.message-tutor {
  display: flex;
  justify-content: flex-start;
}

.message-content {
  max-width: 70%;
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--radius-md);
  font-family: var(--font-conversation);
  font-size: 16px;
  line-height: 1.7;
  box-shadow: var(--shadow-sm);
}

.message-user .message-content {
  background-color: var(--bg-user-message);
  border-left: 4px solid var(--accent-rose);
}

.message-tutor .message-content {
  background-color: var(--bg-tutor-message);
  border-left: 4px solid var(--accent-sage);
}

/* Translation and grammar hints */
.translation {
  color: var(--text-secondary);
  font-style: italic;
  font-size: 14px;
  margin-top: var(--spacing-xs);
}

.grammar-note {
  background-color: rgba(212, 165, 116, 0.1);
  border-left: 3px solid var(--accent-amber);
  padding: var(--spacing-sm) var(--spacing-md);
  margin-top: var(--spacing-md);
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--text-secondary);
}

/* Input area */
.input-area {
  background-color: white;
  border-top: 1px solid var(--border-light);
  padding: var(--spacing-lg);
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.05);
}

.input-container {
  position: relative;
  max-width: 900px;
  margin: 0 auto;
}

.message-input {
  width: 100%;
  min-height: 56px;
  max-height: 200px;
  padding: var(--spacing-md);
  padding-right: 60px;
  border: 2px solid var(--border-light);
  border-radius: var(--radius-md);
  font-family: var(--font-conversation);
  font-size: 16px;
  resize: none;
  outline: none;
  transition: border-color var(--transition-fast);
}

.message-input:focus {
  border-color: var(--accent-sage);
}

.message-input::placeholder {
  color: var(--text-muted);
}

.send-button {
  position: absolute;
  right: 8px;
  bottom: 8px;
  width: 40px;
  height: 40px;
  background-color: var(--accent-navy);
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
  font-size: 20px;
}

.send-button:hover:not(:disabled) {
  background-color: var(--accent-sage);
  transform: scale(1.05);
}

.send-button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

/* Loading indicator */
.loading-indicator {
  display: none;
  align-items: center;
  gap: var(--spacing-sm);
  color: var(--text-muted);
  font-size: 14px;
  font-family: var(--font-ui);
  margin-top: var(--spacing-md);
}

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

.loading-dots {
  display: flex;
  gap: 4px;
}

.loading-dot {
  width: 6px;
  height: 6px;
  background-color: var(--accent-sage);
  border-radius: 50%;
  animation: bounce 1.4s infinite ease-in-out both;
}

.loading-dot:nth-child(1) {
  animation-delay: -0.32s;
}

.loading-dot:nth-child(2) {
  animation-delay: -0.16s;
}

@keyframes bounce {
  0%, 80%, 100% {
    transform: scale(0.8);
    opacity: 0.5;
  }
  40% {
    transform: scale(1);
    opacity: 1;
  }
}

/* Empty state */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  color: var(--text-muted);
  text-align: center;
  padding: var(--spacing-xl);
}

.empty-state-icon {
  font-size: 64px;
  margin-bottom: var(--spacing-lg);
}

.empty-state-title {
  font-family: var(--font-logo);
  font-size: 28px;
  color: var(--text-primary);
  margin-bottom: var(--spacing-md);
}

.empty-state-text {
  font-size: 16px;
  max-width: 400px;
}

/* Mobile responsive */
@media (max-width: 768px) {
  .header {
    padding: 0 var(--spacing-md);
  }

  .conversation-area {
    padding: var(--spacing-md);
  }

  .message-content {
    max-width: 85%;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 15px;
  }

  .input-area {
    padding: var(--spacing-md);
  }

  .message-input {
    font-size: 16px; /* Prevent iOS zoom */
  }
}

/* Error message */
.error-message {
  background-color: #FEE2E2;
  border-left: 4px solid #EF4444;
  padding: var(--spacing-md);
  border-radius: var(--radius-sm);
  color: #991B1B;
  font-size: 14px;
  margin-bottom: var(--spacing-md);
}