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

        body {
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            padding: 20px;
        }

        .container {
            background: #ffffff;
            padding: 40px;
            box-shadow: 0 15px 50px rgba(0, 0, 0, 0.3);
            border-radius: 15px;
            width: 100%;
            max-width: 700px;
        }

        .container h2 {
            color: #333;
            margin-bottom: 25px;
            font-size: 28px;
            text-align: center;
        }

        input[type="number"],
        input[type="text"],
        select {
            width: 100%;
            padding: 12px 15px;
            margin-bottom: 15px;
            border: 2px solid #e0e0e0;
            border-radius: 8px;
            font-size: 16px;
            transition: all 0.3s ease;
            font-family: inherit;
        }

        input[type="number"]:focus,
        input[type="text"]:focus,
        select:focus {
            outline: none;
            border-color: #667eea;
            box-shadow: 0 0 10px rgba(102, 126, 234, 0.2);
        }

        select {
            cursor: pointer;
            appearance: none;
            background-image: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='currentColor' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
            background-repeat: no-repeat;
            background-position: right 15px center;
            background-size: 20px;
            padding-right: 40px;
        }

        input[type="button"] {
            width: 100%;
            padding: 14px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border: none;
            border-radius: 8px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            margin-bottom: 25px;
        }

        input[type="button"]:hover {
            transform: translateY(-2px);
            box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
        }

        input[type="button"]:active {
            transform: translateY(0);
        }

        .square {
            width: 50px;
            height: 50px;
            margin: 8px;
            display: inline-block;
            border-radius: 4px;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15);
            transition: all 0.3s ease;
        }

        .square:hover {
            transform: scale(1.1);
            box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
        }

        .circle {
            width: 50px;
            height: 50px;
            margin: 8px;
            display: inline-block;
            border-radius: 50%;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15);
            transition: all 0.3s ease;
        }

        .circle:hover {
            transform: scale(1.1);
            box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
        }

        .rectangle {
            width: 100px;
            height: 50px;
            margin: 8px;
            display: inline-block;
            border-radius: 6px;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15);
            transition: all 0.3s ease;
        }

        .rectangle:hover {
            transform: scale(1.1);
            box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
        }

        .triangle {
            border-left: 50px solid transparent;
            border-right: 50px solid transparent;
            border-bottom: 100px solid;
            margin: 8px;
            display: inline-block;
            transition: all 0.3s ease;
            filter: drop-shadow(0 4px 8px rgba(0, 0, 0, 0.15));
        }

        .triangle:hover {
            transform: scale(1.1);
            filter: drop-shadow(0 8px 16px rgba(0, 0, 0, 0.2));
        }

        .main {
            margin-top: 30px;
            padding: 30px;
            background: linear-gradient(to bottom right, #f8f9fa, #e8eaf6);
            border-radius: 12px;
            border: 2px dashed #667eea;
            min-height: 200px;
            text-align: center;
        }

        .main:empty::before {
            content: "Shapes will appear here...";
            color: #999;
            font-size: 14px;
        }