/* Modern CSS Variables */
:root {
    --primary-color: #007AFF;
    --primary-hover: #0056b3;
    --secondary-color: #E5E5EA;
    --text-primary: #1d1d1f;
    --text-secondary: #6e6e73;
    --background: #f5f5f7;
    --surface: #ffffff;
    --border: #d2d2d7;
    --shadow: rgba(0, 0, 0, 0.1);
    --success: #34c759;
    --warning: #ff9500;
    --error: #ff3b30;
    --border-radius: 12px;
    --spacing: 20px;
}

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Container Layout */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: var(--spacing);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.header {
    text-align: center;
    margin-bottom: 30px;
}

.header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), #5856d6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 8px;
}

.header p {
    color: var(--text-secondary);
    font-size: 1rem;
    margin-bottom: 10px;
}

.status {
    display: inline-block;
    padding: 4px 12px;
    background: var(--success);
    color: white;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

.status.loading {
    background: var(--warning);
}

.status.error {
    background: var(--error);
}

/* Chat Container */
.chat-container {
    background: var(--surface);
    border-radius: var(--border-radius);
    box-shadow: 0 8px 25px var(--shadow);
    overflow: hidden;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    min-height: 600px;
}

/* Messages Area */
.messages {
    flex-grow: 1;
    overflow-y: auto;
    padding: var(--spacing);
    scroll-behavior: smooth;
    max-height: 70vh;
}

.messages::-webkit-scrollbar {
    width: 6px;
}

.messages::-webkit-scrollbar-track {
    background: transparent;
}

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

.messages::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}

/* Message Styles */
.message {
    margin-bottom: 16px;
    display: flex;
    animation: fadeInUp 0.3s ease-out;
}

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

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

.message.assistant {
    justify-content: flex-start;
}

.message-content {
    max-width: 75%;
    padding: 14px 18px;
    border-radius: 20px;
    font-size: 0.95rem;
    line-height: 1.5;
    word-wrap: break-word;
    position: relative;
}

.message.user .message-content {
    background: var(--primary-color);
    color: white;
    border-bottom-right-radius: 6px;
}

.message.assistant .message-content {
    background: var(--secondary-color);
    color: var(--text-primary);
    border-bottom-left-radius: 6px;
}

/* Welcome Message */
.welcome-message {
    margin-bottom: 20px;
    opacity: 0.9;
}

/* Loading Animation */
.message.loading .message-content {
    opacity: 0.7;
    position: relative;
}

.message.loading .message-content::after {
    content: '';
    display: inline-block;
    width: 20px;
    height: 4px;
    background: linear-gradient(90deg, transparent, var(--text-secondary), transparent);
    border-radius: 2px;
    animation: loading 1.5s infinite;
    margin-left: 8px;
}

@keyframes loading {
    0% { transform: translateX(-20px); opacity: 0; }
    50% { opacity: 1; }
    100% { transform: translateX(20px); opacity: 0; }
}

/* Input Area */
.input-area {
    padding: var(--spacing);
    border-top: 1px solid var(--border);
    display: flex;
    gap: 12px;
    align-items: center;
    background: var(--surface);
}

.input-area input {
    flex: 1;
    padding: 14px 18px;
    border: 2px solid var(--border);
    border-radius: 25px;
    outline: none;
    font-size: 1rem;
    transition: all 0.2s ease;
    background: var(--background);
}

.input-area input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 122, 255, 0.1);
}

.input-area button {
    padding: 14px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
}

.input-area button:hover {
    background: var(--primary-hover);
    transform: scale(1.05);
}

.input-area button:active {
    transform: scale(0.95);
}

.send-icon {
    font-size: 1.2rem;
    transform: rotate(-45deg);
}

/* Controls */
.controls {
    display: flex;
    justify-content: center;
    gap: 12px;
    margin-top: 20px;
}

.control-btn {
    padding: 10px 16px;
    background: var(--surface);
    color: var(--text-secondary);
    border: 1px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 6px;
}

.control-btn:hover {
    background: var(--border);
    transform: translateY(-1px);
    box-shadow: 0 2px 8px var(--shadow);
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 16px;
    }
    
    .header h1 {
        font-size: 2rem;
    }
    
    .message-content {
        max-width: 85%;
        font-size: 0.9rem;
    }
    
    .input-area {
        padding: 16px;
    }
    
    .controls {
        flex-wrap: wrap;
    }
    
    .control-btn {
        font-size: 0.8rem;
        padding: 8px 12px;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 1.8rem;
    }
    
    .message-content {
        max-width: 90%;
        padding: 12px 16px;
    }
    
    .input-area input {
        font-size: 16px; /* Prevents zoom on iOS */
    }
}

/* Dark Mode Support */
@media (prefers-color-scheme: dark) {
    :root {
        --text-primary: #f2f2f7;
        --text-secondary: #98989d;
        --background: #000000;
        --surface: #1c1c1e;
        --border: #38383a;
        --secondary-color: #2c2c2e;
        --shadow: rgba(0, 0, 0, 0.3);
    }
    
    .input-area input {
        background: var(--background);
        color: var(--text-primary);
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus styles for keyboard navigation */
button:focus-visible,
input:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}