:root {
    --primary-color: #667eea;
    --primary-hover: #5a67d8;
    --primary-light: #e6fffa;
    --secondary-color: #4fd1c7;
    --background: #f8fafc;
    --card-background: #ffffff;
    --error-color: #f56565;
    --success-color: #48bb78;
    --warning-color: #ed8936;
    --text-primary: #2d3748;
    --text-secondary: #718096;
    --text-muted: #a0aec0;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 0;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    min-height: 100vh;
}

.api-key-section {
    position: fixed;
    top: 20px;
    left: 20px;
    width: 280px;
    background: var(--card-background);
    padding: 20px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    z-index: 1000;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.api-key-section h4 {
    margin: 0 0 15px 0;
    color: var(--text-primary);
    font-size: 16px;
    font-weight: 600;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

#loginSection {
    background: var(--card-background);
    padding: 40px;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 450px;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

#loginSection h2 {
    text-align: center;
    margin-bottom: 30px;
    color: var(--text-primary);
    font-size: 28px;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

input {
    width: 100%;
    padding: 16px 20px;
    margin: 12px 0;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    outline: none;
    transition: all 0.3s ease;
    font-size: 16px;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
}

input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
    transform: translateY(-2px);
}

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

button {
    width: 100%;
    padding: 16px 24px;
    margin: 12px 0;
    border: none;
    border-radius: var(--radius-md);
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    color: white;
    font-weight: 600;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

button:active {
    transform: translateY(0);
}

button::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

button:hover::before {
    left: 100%;
}

.toggle-btn {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-secondary);
    border: 2px solid var(--border-color);
    backdrop-filter: blur(10px);
}

.toggle-btn.active {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    color: white;
    border-color: var(--primary-color);
}

.login-toggle {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
    margin-bottom: 30px;
}

.error-message {
    color: var(--error-color);
    background: rgba(245, 101, 101, 0.1);
    border: 1px solid rgba(245, 101, 101, 0.2);
    border-radius: var(--radius-md);
    padding: 16px;
    margin: 12px 0;
    font-weight: 500;
    animation: slideIn 0.3s ease;
}

.success-message {
    background: rgba(72, 187, 120, 0.1);
    border: 1px solid rgba(72, 187, 120, 0.2);
    border-radius: var(--radius-lg);
    padding: 30px;
    color: var(--success-color);
    animation: slideIn 0.3s ease;
}

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

#homePage {
    width: 100%;
    max-width: none;
    background: var(--card-background);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    overflow: hidden;
}

.nav-bar {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    color: white;
    padding: 20px 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
}

.nav-bar h2 {
    margin: 0;
    font-size: 24px;
    font-weight: 600;
}

.nav-buttons {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.nav-buttons button {
    width: auto;
    margin: 0;
    padding: 12px 20px;
    font-size: 14px;
    font-weight: 500;
}

.main-layout {
    display: grid;
    grid-template-columns: 1fr 320px;
    gap: 0;
    min-height: 80vh;
}

.main-content {
    padding: 30px;
    overflow-y: auto;
}

.users-sidebar {
    background: linear-gradient(180deg, rgba(102, 126, 234, 0.05), rgba(118, 75, 162, 0.05));
    border-left: 1px solid var(--border-color);
    padding: 30px 20px;
    overflow-y: auto;
}

.dashboard-section {
    display: grid;
    gap: 25px;
}

.room-creation-card, .rooms-list, .online-users-card {
    background: var(--card-background);
    padding: 25px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
}

.room-creation-card:hover, .rooms-list:hover, .online-users-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.room-creation-card h4, .rooms-list h4, .online-users-card h4 {
    margin: 0 0 20px 0;
    color: var(--text-primary);
    font-size: 18px;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 10px;
}

.room-creation-card h4::before {
    content: '🏠';
    font-size: 20px;
}

.rooms-list h4::before {
    content: '💬';
    font-size: 20px;
}

.online-users-card h4::before {
    content: '👥';
    font-size: 20px;
}

select {
    width: 100%;
    padding: 16px 20px;
    margin: 12px 0;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    outline: none;
    transition: all 0.3s ease;
    background: var(--card-background);
    cursor: pointer;
    font-size: 16px;
}

select:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.room-item, .user-item {
    display: flex;
    align-items: center;
    padding: 15px;
    border-radius: var(--radius-md);
    margin-bottom: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    border: 1px solid transparent;
    background: rgba(255, 255, 255, 0.5);
}

.room-item:hover, .user-item:hover {
    background: rgba(102, 126, 234, 0.1);
    border-color: var(--primary-color);
    transform: translateX(5px);
}

.user-status {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    margin-right: 12px;
    background: var(--text-muted);
    position: relative;
    transition: all 0.3s ease;
}

.user-status.status-online {
    background: var(--success-color);
    box-shadow: 0 0 8px rgba(72, 187, 120, 0.5);
}

.user-status.status-online::after {
    content: '';
    position: absolute;
    top: -2px;
    left: -2px;
    right: -2px;
    bottom: -2px;
    border: 2px solid var(--success-color);
    border-radius: 50%;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% {
        transform: scale(1);
        opacity: 1;
    }
    100% {
        transform: scale(1.5);
        opacity: 0;
    }
}

.user-name {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 14px;
}

.user-status-text {
    font-size: 12px;
    color: var(--text-muted);
    font-weight: 500;
}

.user-status-text.online {
    color: var(--success-color);
}

.user-item.online {
    background: rgba(72, 187, 120, 0.05);
    border-color: rgba(72, 187, 120, 0.2);
}

.chat-interface {
    background: var(--card-background);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    overflow: hidden;
    border: 1px solid var(--border-color);
    animation: slideUp 0.3s ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.chat-header {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    color: white;
    padding: 20px;
    display: flex;
    align-items: center;
    gap: 15px;
}

.chat-header h4 {
    margin: 0;
    flex: 1;
    font-size: 18px;
    font-weight: 600;
}

.back-btn, .invite-btn {
    background: rgba(255, 255, 255, 0.2);
    border: none;
    color: white;
    padding: 10px 15px;
    cursor: pointer;
    border-radius: var(--radius-md);
    font-size: 14px;
    font-weight: 600;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

.back-btn:hover, .invite-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: scale(1.05);
}

.invite-btn {
    background: var(--success-color);
    margin-left: auto;
}

.messages-container {
    height: 400px;
    overflow-y: auto;
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    background: linear-gradient(180deg, rgba(102, 126, 234, 0.02), rgba(255, 255, 255, 0.05));
}

.message {
    max-width: 75%;
    padding: 12px 18px;
    border-radius: 18px;
    margin: 4px 0;
    word-wrap: break-word;
    animation: messageSlide 0.3s ease;
    position: relative;
}

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

.message.sent {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    color: white;
    align-self: flex-end;
    border-bottom-right-radius: 6px;
    box-shadow: var(--shadow-sm);
}

.message.received {
    background: rgba(102, 126, 234, 0.1);
    color: var(--text-primary);
    align-self: flex-start;
    border-bottom-left-radius: 6px;
    border: 1px solid rgba(102, 126, 234, 0.2);
}

.sender-name {
    font-size: 12px;
    font-weight: 600;
    color: var(--primary-color);
    display: block;
    margin-bottom: 4px;
}

.message-form {
    display: flex;
    gap: 12px;
    padding: 20px;
    background: rgba(102, 126, 234, 0.02);
    border-top: 1px solid var(--border-color);
}

.message-form input {
    margin: 0;
    flex: 1;
}

.message-form button {
    width: auto;
    margin: 0;
    padding: 16px 24px;
    background: linear-gradient(135deg, var(--secondary-color), #38b2ac);
}

.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.6);
    z-index: 2000;
    backdrop-filter: blur(5px);
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.modal-content {
    background: var(--card-background);
    margin: 5% auto;
    padding: 30px;
    width: 90%;
    max-width: 550px;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    animation: slideUp 0.3s ease;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h4 {
    margin: 0;
    color: var(--text-primary);
    font-size: 20px;
    font-weight: 600;
}

.close-btn {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: var(--text-muted);
    padding: 5px;
    border-radius: var(--radius-md);
    transition: all 0.3s ease;
}

.close-btn:hover {
    background: rgba(245, 101, 101, 0.1);
    color: var(--error-color);
}

.user-selection {
    max-height: 300px;
    overflow-y: auto;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 10px;
}

.user-checkbox-item {
    display: flex;
    align-items: center;
    padding: 12px;
    gap: 12px;
    border-radius: var(--radius-md);
    transition: all 0.3s ease;
    cursor: pointer;
}

.user-checkbox-item:hover {
    background: rgba(102, 126, 234, 0.05);
}

.user-checkbox-item input[type="checkbox"] {
    width: auto;
    margin: 0;
    accent-color: var(--primary-color);
}

.user-checkbox-item label {
    cursor: pointer;
    font-weight: 500;
    color: var(--text-primary);
}

.modal-footer {
    margin-top: 25px;
    display: flex;
    gap: 12px;
    justify-content: flex-end;
    padding-top: 15px;
    border-top: 1px solid var(--border-color);
}

.secondary-btn {
    background: rgba(160, 174, 192, 0.2);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}

/* Responsive Design */
@media (max-width: 1200px) {
    .main-layout {
        grid-template-columns: 1fr 280px;
    }
}

@media (max-width: 768px) {
    body {
        background: var(--background);
    }
    
    .container {
        padding: 10px;
    }
    
    .api-key-section {
        position: relative;
        width: 100%;
        margin-bottom: 20px;
        top: auto;
        left: auto;
    }
    
    #loginSection {
        padding: 30px 20px;
        margin: 10px;
    }
    
    .main-layout {
        grid-template-columns: 1fr;
        gap: 0;
    }
    
    .users-sidebar {
        order: -1;
        border-left: none;
        border-bottom: 1px solid var(--border-color);
        padding: 20px;
        max-height: 300px;
        overflow-y: auto;
    }
    
    .main-content {
        padding: 20px;
    }
    
    .nav-bar {
        padding: 15px 20px;
        flex-direction: column;
        text-align: center;
        gap: 15px;
    }
    
    .nav-bar h2 {
        font-size: 20px;
    }
    
    .nav-buttons {
        justify-content: center;
    }
    
    .room-creation-card, .rooms-list, .online-users-card {
        padding: 20px;
    }
    
    .messages-container {
        height: 300px;
        padding: 15px;
    }
    
    .message {
        max-width: 85%;
        padding: 10px 15px;
    }
    
    .message-form {
        padding: 15px;
        flex-direction: column;
        gap: 10px;
    }
    
    .message-form button {
        width: 100%;
    }
    
    .modal-content {
        margin: 10% auto;
        padding: 20px;
        width: 95%;
    }
    
    .modal-footer {
        flex-direction: column;
    }
    
    .login-toggle {
        grid-template-columns: 1fr;
        gap: 8px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 5px;
    }
    
    #loginSection {
        padding: 25px 15px;
        margin: 5px;
    }
    
    #loginSection h2 {
        font-size: 24px;
    }
    
    input, button, select {
        padding: 14px 16px;
        font-size: 16px; /* Prevents zoom on iOS */
    }
    
    .nav-bar h2 {
        font-size: 18px;
    }
    
    .main-content {
        padding: 15px;
    }
    
    .room-creation-card, .rooms-list, .online-users-card {
        padding: 15px;
    }
    
    .chat-header {
        padding: 15px;
    }
    
    .chat-header h4 {
        font-size: 16px;
    }
    
    .messages-container {
        height: 250px;
        padding: 10px;
    }
    
    .message-form {
        padding: 10px;
    }
    
    .modal-content {
        padding: 15px;
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --background: #1a202c;
        --card-background: #2d3748;
        --text-primary: #f7fafc;
        --text-secondary: #e2e8f0;
        --text-muted: #a0aec0;
        --border-color: #4a5568;
    }
    
    body {
        background: linear-gradient(135deg, #2d3748 0%, #1a202c 100%);
    }
}

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

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

/* Loading states */
.loading-messages {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 40px;
    color: var(--text-muted);
    font-style: italic;
}

.loading-messages::before {
    content: '⏳';
    margin-right: 10px;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

/* Utility classes */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }
.hidden { display: none; }
.visible { display: block; }