body {
    font-family: 'Segoe UI', system-ui, sans-serif;
    background: linear-gradient(rgba(0,0,0,0.35), rgba(0,0,0,0.45)),
                url('https://images6.alphacoders.com/135/thumb-1920-1355194.jpeg') no-repeat center center fixed;
    background-size: cover;
    color: white;
    margin: 0;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: flex-start;
    padding-left: 8%;
}

.container {
    max-width: 620px;
    width: 100%;
    background: rgba(255,255,255,0.13);
    backdrop-filter: blur(14px);
    border-radius: 24px;
    padding: 45px 35px;
    box-shadow: 0 25px 60px rgba(0,0,0,0.5);
    text-align: center;
    margin-left: 40px;
}

h1 {
    margin-bottom: 35px;
    font-size: 2.9em;
    text-shadow: 0 4px 20px rgba(0,0,0,0.4);
}

button {
    background: white;
    color: #4c51bf;
    border: none;
    padding: 14px 28px;
    margin: 8px;
    border-radius: 50px;
    font-size: 1.1em;
    cursor: pointer;
    transition: all 0.2s;
    font-weight: 600;
}

button:hover {
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 10px 25px rgba(0,0,0,0.25);
}

.question {
    font-size: 7.5em;
    margin: 30px 0;
    cursor: pointer;
    transition: transform 0.2s;
    text-shadow: 0 4px 15px rgba(0,0,0,0.3);
}

.question:hover {
    transform: scale(1.08);
}

input {
    background: rgba(255,255,255,0.95);
    color: #222;
    border: none;
    border-radius: 14px;
    padding: 18px;
    font-size: 1.7em;
    width: 75%;
    max-width: 440px;
    text-align: center;
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.feedback {
    font-size: 1.7em;
    margin: 25px 0;
    padding: 18px;
    border-radius: 16px;
}

.correct { background: rgba(72, 187, 120, 0.95); }
.incorrect { background: rgba(245, 101, 101, 0.95); }

.progress {
    font-size: 1.4em;
    margin-bottom: 15px;
    opacity: 0.9;
}

.hidden {
    display: none;
}