:root {
    --primary: #3498db;
    --success: #2ecc71;
    --dark: #2c3e50;
    --light: #f8f9fa;
}

body {
    font-family: -apple-system, system-ui, sans-serif;
    background-color: var(--light);
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    touch-action: manipulation;
}

.container {
    width: 90%;
    max-width: 400px;
    text-align: center;
}

h1 { color: var(--dark); margin-bottom: 30px; }

.card-container {
    perspective: 1000px;
    height: 280px;
    margin-bottom: 25px;
}

.card {
    width: 100%;
    height: 100%;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    cursor: pointer;
}

.card.is-flipped { transform: rotateY(180deg); }

.card-front, .card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background: white;
    border-radius: 20px;
    box-shadow: 0 8px 20px rgba(0,0,0,0.1);
    padding: 30px;
    box-sizing: border-box;
}

.card-front { font-size: 1.8rem; color: var(--dark); font-weight: 700; }
.card-front small { font-size: 0.8rem; color: #95a5a6; margin-top: 15px; }

.voice-status {
    font-size: 0.8rem;
    color: #7f8c8d;
    margin-bottom: 10px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
}
#voice-type {
    color: var(--primary);
}

.card-back {
    background-color: var(--primary);
    color: white;
    transform: rotateY(180deg);
    font-size: 1.5rem;
}

.controls { display: flex; gap: 10px; justify-content: center; }

button {
    padding: 15px 20px;
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.1s;
}

.btn-audio { background: var(--success); color: white; flex: 1; }
.btn-next { background: var(--dark); color: white; flex: 2; }

.progress { margin-top: 25px; color: #7f8c8d; }