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

:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-muted: #adb5bd;
    --border-color: #dee2e6;
    --accent-color: #0d6efd;
    --success-color: #198754;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --shadow: 0 0.125rem 0.25rem rgba(0, 0, 0, 0.075);
    --shadow-lg: 0 1rem 3rem rgba(0, 0, 0, 0.175);
}

[data-theme="dark"] {
    --bg-primary: #212529;
    --bg-secondary: #2d3338;
    --bg-tertiary: #343a40;
    --text-primary: #f8f9fa;
    --text-secondary: #adb5bd;
    --text-muted: #6c757d;
    --border-color: #495057;
    --accent-color: #0d6efd;
    --success-color: #198754;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --shadow: 0 0.125rem 0.25rem rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 1rem 3rem rgba(0, 0, 0, 0.5);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    height: 100vh;
    overflow: hidden;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Utility Classes */
.hidden {
    display: none !important;
}

/* Username Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(8px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.modal-content {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    max-width: 420px;
    width: 90%;
    box-shadow: var(--shadow-lg);
    animation: modalSlideIn 0.3s ease-out;
}

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

.modal-header h2 {
    color: var(--text-primary);
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.modal-header p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    font-size: 0.95rem;
}

.input-group {
    position: relative;
    margin-bottom: 1.5rem;
}

.input-group input {
    width: 100%;
    padding: 0.875rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-secondary);
    font-size: 1rem;
    color: var(--text-primary);
    transition: all 0.2s ease;
    outline: none;
}

.input-group input:focus {
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(13, 110, 253, 0.1);
    background: var(--bg-primary);
}

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

#joinButton {
    width: 100%;
    padding: 0.875rem 1rem;
    background: var(--accent-color);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
}

#joinButton:hover {
    background: #0b5ed7;
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

/* Chat Interface */
#chatInterface {
    height: 100vh;
    display: flex;
    flex-direction: column;
    margin: 10px;
    height: calc(100vh - 20px);
    border-radius: 12px;
    border: 1px solid var(--border-color);
    overflow: hidden;
    background: var(--bg-primary);
}

/* Header */
.chat-header {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header-left h1 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0;
}

#participantCount {
    color: var(--text-secondary);
    font-size: 0.9rem;
    background: var(--bg-primary);
    padding: 0.25rem 0.5rem;
    border-radius: 6px;
    border: 1px solid var(--border-color);
}

.header-btn {
    padding: 0.5rem 1rem;
    background: var(--accent-color);
    border: none;
    border-radius: 6px;
    cursor: pointer;
    color: white;
    font-size: 0.875rem;
    font-weight: 500;
    transition: all 0.2s ease;
}

.header-btn:hover {
    background: #0b5ed7;
    transform: translateY(-1px);
}

/* Main Chat Area */
.chat-main {
    flex: 1;
    position: relative;
    padding: 1rem;
    overflow: hidden;
    background: var(--bg-primary);
}

/* Video Grid */
.video-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    height: 100%;
    justify-content: flex-start;
    align-items: flex-start;
    padding: 1rem;
}

.remoteVideoContainer {
    position: relative;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    min-width: 200px;
    aspect-ratio: 16 / 9;
    box-shadow: var(--shadow);
    transition: all 0.2s ease;
}

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

.remoteVideo {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.remoteUsername {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(0, 0, 0, 0.8);
    color: white;
    padding: 0.5rem;
    font-size: 0.875rem;
    font-weight: 500;
    backdrop-filter: blur(10px);
}

/* Responsive grid sizing */
.remoteVideoContainer:only-child {
    width: min(70vw, 800px);
}

.video-grid:has(.remoteVideoContainer:nth-child(2)) .remoteVideoContainer {
    width: min(45vw, 500px);
}

.video-grid:has(.remoteVideoContainer:nth-child(3)) .remoteVideoContainer {
    width: min(30vw, 350px);
}

.video-grid:has(.remoteVideoContainer:nth-child(4)) .remoteVideoContainer {
    width: min(22vw, 280px);
}

/* Self View */
.self-view {
    position: fixed;
    bottom: 4rem;
    right: 1rem;
    width: 200px;
    aspect-ratio: 16 / 9;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    z-index: 200;
}

.self-view:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

#selfVideo {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transform: scaleX(-1); /* Mirror effect */
}

.self-view-label {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(0, 0, 0, 0.8);
    color: white;
    padding: 0.25rem;
    font-size: 0.75rem;
    font-weight: 500;
    text-align: center;
    backdrop-filter: blur(10px);
}

/* Chat Controls */
.chat-controls {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: 1rem;
    display: flex;
    justify-content: center;
    gap: 1rem;
}

.control-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border: 1px solid var(--border-color);
    background: var(--bg-primary);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    color: var(--text-primary);
    font-size: 0.875rem;
    font-weight: 500;
}

.control-btn:hover {
    background: var(--accent-color);
    color: white;
    border-color: var(--accent-color);
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

.control-btn span {
    font-size: 0.875rem;
}

.mute-btn.muted {
    background: #dc3545;
    color: white;
    border-color: #dc3545;
}

.mute-btn.muted:hover {
    background: #c82333;
    transform: translateY(-1px);
}

.video-btn.disabled {
    background: #dc3545;
    color: white;
    border-color: #dc3545;
}

.video-btn.disabled:hover {
    background: #c82333;
    transform: translateY(-1px);
}

.hangup-btn {
    background: #dc3545;
    color: white;
    border-color: #dc3545;
}

.hangup-btn:hover {
    background: #c82333;
    transform: translateY(-1px);
}

/* Mobile Responsiveness */
@media (max-width: 768px) {
    .chat-header {
        padding: 1rem;
    }
    
    .header-left h1 {
        font-size: 1.2rem;
    }
    
    .chat-main {
        padding: 0.5rem;
    }
    
    .remoteVideoContainer:only-child {
        width: 90vw;
    }
    
    .video-grid:has(.remoteVideoContainer:nth-child(2)) .remoteVideoContainer {
        width: 45vw;
    }
    
    .video-grid:has(.remoteVideoContainer:nth-child(3)) .remoteVideoContainer {
        width: 45vw;
    }
    
    .video-grid:has(.remoteVideoContainer:nth-child(4)) .remoteVideoContainer {
        width: 45vw;
    }
    
    .self-view {
        width: 120px;
        bottom: 6rem;
    }
    
    .chat-controls {
        gap: 0.5rem;
        padding: 0.75rem;
    }
    
    .control-btn {
        padding: 0.75rem;
        min-width: 60px;
    }
    
    .control-btn span {
        font-size: 0.8rem;
    }
}