:root {
    --primary: #007bff;
    --success: #28a745;
    --danger: #dc3545;
    --warning: #ffc107;
    --secondary: #6c757d;
    --bg: #f4f4f9;
    --card-bg: #ffffff;
    --text: #333;
}
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg);
    color: var(--text);
    margin: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}
.container {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 20px;
    max-width: 600px;
    margin: 0 auto;
    width: 100%;
    box-sizing: border-box;
}
h1 {
    font-size: 1.8rem;
    margin-bottom: 20px;
    text-align: center;
    color: #444;
}
.card {
    background: var(--card-bg);
    padding: 25px;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
    width: 100%;
    text-align: center;
    box-sizing: border-box;
    margin-bottom: 20px;
}
.label {
    font-size: 0.9rem;
    color: #666;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 10px;
}
.question {
    font-size: 1.6rem;
    font-weight: 700;
    margin: 15px 0 25px 0;
    word-wrap: break-word;
}
input[type="text"] {
    width: 100%;
    padding: 12px 15px;
    font-size: 1.1rem;
    border: 2px solid #ddd;
    border-radius: 8px;
    box-sizing: border-box;
    outline: none;
    transition: border-color 0.3s;
    -webkit-appearance: none;
}
input[type="text"]:focus {
    border-color: var(--primary);
}
button {
    width: 100%;
    padding: 14px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 10px;
    transition: transform 0.1s, opacity 0.2s;
    -webkit-tap-highlight-color: transparent;
}
button:active {
    transform: scale(0.98);
}
.mode-select {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 8px;
    margin-bottom: 20px;
    width: 100%;
}
.mode-select button {
    font-size: 0.9rem;
    padding: 10px 5px;
    background: #e0e0e0;
    color: #555;
    margin-bottom: 0;
}
.mode-select button.active {
    background: var(--primary);
    color: white;
}
.action-btn.primary { background-color: var(--primary); color: white; }
.action-btn.secondary { background-color: var(--secondary); color: white; }
.action-btn.danger { background-color: var(--danger); color: white; }
.action-btn { margin-top: 5px; }
#feedback-msg {
    margin-top: 15px;
    min-height: 1.2em;
    font-weight: 500;
    line-height: 1.4;
}
.msg-correct { color: var(--success); }
.msg-wrong { color: var(--danger); }
.msg-typo { color: #d39e00; }
.overlay {
    display: none;
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background: rgba(0,0,0,0.6);
    z-index: 1000;
    justify-content: center;
    align-items: center;
    padding: 20px;
    box-sizing: border-box;
}
.overlay-content {
    background: white;
    padding: 20px;
    border-radius: 12px;
    width: 100%;
    max-width: 400px;
    max-height: 80vh;
    display: flex;
    flex-direction: column;
}
.page-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(70px, 1fr));
    gap: 10px;
    margin: 20px 0;
    overflow-y: auto;
    flex: 1;
}
.page-item { position: relative; }
.page-item input[type="checkbox"] {
    position: absolute;
    opacity: 0;
    width: 100%;
    height: 100%;
    cursor: pointer;
}
.page-item label {
    display: block;
    padding: 10px;
    background: #f0f0f0;
    border-radius: 6px;
    text-align: center;
    font-weight: bold;
    color: #555;
    border: 2px solid transparent;
    transition: all 0.2s;
}
.page-item input:checked + label {
    background: #e3f2fd;
    border-color: var(--primary);
    color: var(--primary);
}
.progress-container {
    background: #fff;
    border-top: 1px solid #eee;
    padding: 15px 20px;
    width: 100%;
    box-sizing: border-box;
    position: sticky;
    bottom: 0;
}
.progress-text {
    text-align: center;
    margin-bottom: 8px;
    font-size: 0.9rem;
    font-weight: 600;
    color: #555;
}
.progress-bar-bg {
    background: #e9ecef;
    height: 12px;
    border-radius: 6px;
    overflow: hidden;
}
.progress-bar-fill {
    height: 100%;
    width: 0%;
    transition: width 0.4s ease, background-color 0.4s ease;
}
@media (max-width: 480px) {
    h1 { font-size: 1.5rem; }
    .card { padding: 20px; }
    .question { font-size: 1.4rem; }
    .mode-select { display: flex; flex-direction: column; }
    .mode-select button { width: 100%; padding: 12px; }
}