:root{font-family:system-ui,Avenir,Helvetica,Arial,sans-serif;line-height:1.5;font-weight:400;color-scheme:light dark;color:#ffffffde;background-color:#242424;font-synthesis:none;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}a{font-weight:500;color:#646cff;text-decoration:inherit}a:hover{color:#535bf2}body{margin:0;display:flex;place-items:center;min-width:320px;min-height:100vh}h1{font-size:3.2em;line-height:1.1}button{border-radius:8px;border:1px solid transparent;padding:.6em 1.2em;font-size:1em;font-weight:500;font-family:inherit;background-color:#1a1a1a;cursor:pointer;transition:border-color .25s}button:hover{border-color:#646cff}button:focus,button:focus-visible{outline:4px auto -webkit-focus-ring-color}@media(prefers-color-scheme:light){:root{color:#213547;background-color:#fff}a:hover{color:#747bff}button{background-color:#f9f9f9}}*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;background:linear-gradient(135deg,#667eea,#764ba2);min-height:100vh}.app{min-height:100vh;display:flex;flex-direction:column}.app-header{background:#fffffff2;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);padding:1rem 2rem;box-shadow:0 2px 10px #0000001a;display:flex;justify-content:space-between;align-items:center}.app-header h1{font-size:1.8rem;background:linear-gradient(135deg,#667eea,#764ba2);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.app-main{flex:1;padding:2rem;display:flex;justify-content:center;align-items:center}.home-container{max-width:800px;width:100%}.hero{text-align:center;color:#fff;margin-bottom:3rem}.hero h2{font-size:2.5rem;margin-bottom:1rem}.hero p{font-size:1.2rem;opacity:.9}.auth-container{display:grid;grid-template-columns:1fr auto 1fr;gap:2rem;align-items:center}.divider{font-size:1.2rem;font-weight:700;color:#fff;opacity:.7}.create-session,.join-session{background:#fff;padding:2rem;border-radius:12px;box-shadow:0 8px 30px #0003}.create-session h2,.join-session h2{margin-bottom:1.5rem;color:#333;font-size:1.5rem}.form-group{margin-bottom:1.5rem}.form-group label{display:block;margin-bottom:.5rem;color:#555;font-weight:500}.form-group input{width:100%;padding:.75rem;border:2px solid #e0e0e0;border-radius:8px;font-size:1rem;transition:border-color .3s}.form-group input:focus{outline:none;border-color:#667eea}.error{color:#e53e3e;background:#fff5f5;padding:.75rem;border-radius:8px;margin-bottom:1rem;font-size:.9rem}button{padding:.75rem 1.5rem;border:none;border-radius:8px;font-size:1rem;font-weight:600;cursor:pointer;transition:all .3s}button:disabled{opacity:.5;cursor:not-allowed}.create-session button,.join-session button{width:100%;background:linear-gradient(135deg,#667eea,#764ba2);color:#fff}.create-session button:hover:not(:disabled),.join-session button:hover:not(:disabled){transform:translateY(-2px);box-shadow:0 4px 12px #667eea66}.btn-secondary{background:#e0e0e0;color:#333}.btn-secondary:hover{background:#d0d0d0}.btn-danger{background:#e53e3e;color:#fff}.btn-danger:hover{background:#c53030}.session-info{background:#fff;padding:1.5rem;border-radius:12px;box-shadow:0 4px 20px #0000001a;margin-bottom:1rem}.session-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:1rem}.session-title h3{font-size:1.3rem;color:#333;margin-bottom:.25rem}.session-code{font-family:monospace;background:#f0f0f0;padding:.25rem .5rem;border-radius:4px;font-size:.9rem;color:#666}.session-actions{display:flex;gap:.5rem}.session-stats{display:flex;gap:1.5rem;padding-top:1rem;border-top:1px solid #e0e0e0}.stat{font-size:.95rem;color:#666}.whiteboard-container{width:100%;max-width:1920px}.teacher-canvas-container{background:#fff;padding:1.5rem;border-radius:12px;box-shadow:0 8px 30px #0003}.toolbar{display:flex;gap:1.5rem;margin-bottom:1rem;padding:1rem;background:#f8f8f8;border-radius:8px;flex-wrap:wrap}.tool-group{display:flex;gap:.5rem;align-items:center}.toolbar button{padding:.5rem 1rem;background:#fff;border:2px solid #e0e0e0;color:#333}.toolbar button.active{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff;border-color:transparent}.toolbar button:hover:not(:disabled){border-color:#667eea}.toolbar label{display:flex;gap:.5rem;align-items:center;font-size:.9rem;color:#555}.toolbar input[type=color]{width:50px;height:32px;border:2px solid #e0e0e0;border-radius:4px;cursor:pointer}.toolbar input[type=range]{width:100px}canvas{display:block;max-width:100%;height:auto}.student-canvas-container{background:#fff;padding:1.5rem;border-radius:12px;box-shadow:0 8px 30px #0003}.view-only-banner{background:linear-gradient(135deg,#48bb78,#38a169);color:#fff;padding:1rem;border-radius:8px;margin-bottom:1rem;text-align:center;font-weight:600}.loading{text-align:center;font-size:1.2rem;color:#fff;padding:3rem}.app-footer{background:#0003;color:#fff;text-align:center;padding:1rem;font-size:.9rem}@media(max-width:768px){.auth-container{grid-template-columns:1fr}.divider{text-align:center}.session-header{flex-direction:column;align-items:flex-start;gap:1rem}.toolbar{flex-direction:column}canvas{width:100%;height:auto}}