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

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: #9cb9e4;
            padding: 20px;
            min-height: 100vh;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
        }

        h1 {
            text-align: center;
            font-size: 3em;
            color: #2c3e50;
            margin-bottom: 30px;
        }

        .date-selector {
            background: white;
            padding: 20px;
            border-radius: 10px;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 15px;
            margin-bottom: 30px;
            flex-wrap: wrap;
        }

        .date-selector select {
            padding: 10px 15px;
            font-size: 1.1em;
            border: 2px solid #ddd;
            border-radius: 5px;
            background: white;
            min-width: 150px;
        }

        .change-btn {
            padding: 10px 25px;
            font-size: 1.1em;
            background: #3498db;
            color: white;
            border: none;
            border-radius: 5px;
            cursor: pointer;
            transition: background 0.3s;
        }

        .change-btn:hover {
            background: #2980b9;
        }

        .facts-container {
            background: #999;
            padding: 30px;
            border-radius: 15px;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
            margin-bottom: 20px;
            min-height: 600px;
            display: grid;
            grid-template-columns: 1fr 1fr;
            grid-template-rows: 1fr 1fr;
            gap: 20px;
        }

        .fact-box {
            background: white;
            padding: 25px;
            border-radius: 10px;
            cursor: pointer;
            transition: all 0.3s;
            border: 3px solid transparent;
            display: flex;
            flex-direction: column;
            justify-content: center;
        }

        .fact-box:hover {
            transform: scale(1.02);
        }

        .fact-box.selected {
            background: #dfe3ff;
            border-color: #999;
        }

        .fact-box.correct {
            background: #90EE90;
            border-color: #4CAF50;
        }

        .fact-box.incorrect {
            background: #ffcccb;
            border-color: #f44336;
        }

        .fact-box.reveal-correct {
            background: #FFEB3B;
            border-color: #faba19;
        }

        .fact-text {
            font-size: 1.05em;
            line-height: 1.6;
            color: #2c3e50;
            margin-bottom: 10px;
        }

        .fact-date {
            font-size: 0.9em;
            color: #7f8c8d;
            font-weight: bold;
            display: none;
            margin-top: 10px;
            padding-top: 10px;
            border-top: 2px solid #bdc3c7;
        }

        .fact-box.revealed .fact-date {
            display: block;
        }

        .submit-container {
            text-align: center;
        }

        .submit-btn {
            padding: 15px 50px;
            font-size: 1.3em;
            background: #27ae60;
            color: white;
            border: none;
            border-radius: 10px;
            cursor: pointer;
            transition: all 0.3s;
            font-weight: bold;
        }

        .submit-btn:hover:not(:disabled) {
            background: #229954;
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(39, 174, 96, 0.4);
        }

        .submit-btn:disabled {
            background: #95a5a6;
            cursor: not-allowed;
            opacity: 0.6;
        }

        @media (max-width: 768px) {
            h1 {
                font-size: 2em;
            }

            .facts-container {
                padding: 15px;
                grid-template-columns: 1fr;
                grid-template-rows: auto;
                min-height: auto;
            }

            .fact-box {
                padding: 15px;
            }
        }