* {
    box-sizing: border-box;
}

body {
    font-family: 'Atkinson Hyperlegible Mono', sans-serif;
    font-size: 16px;
    margin: 0;
    padding: 0;
    background-color: #f5f5f5;
    color: #333333;
}

nav {
    background-color: #0056b3;
    padding: 10px 20px;
}

nav a {
    color: white;
    text-decoration: none;
    font-size: 16px;
    font-weight: bold;
}

nav a:hover {
    color: #ffeb3b;
}

header {
    background-color: #007bff;
    color: white;
    padding: 20px 0;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

header h1 {
    margin: 0;
    font-size: 32px;
}

header p {
    margin: 10px 0 0 0;
    font-size: 16px;
    font-style: italic;
}

.container {
    max-width: 980px;
    margin: 0 auto;
    padding: 20px;
}

.controls-section {
    background-color: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    display: flex;
    flex-direction: column;
    gap: 16px;
    margin-bottom: 20px;
}

.control-row {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
    align-items: flex-end;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
    min-width: 180px;
}

.control-group label {
    font-weight: bold;
    font-size: 13px;
    color: #555;
}

.control-group select,
.control-group input[type="number"] {
    padding: 8px 12px;
    font-size: 14px;
    border: 1px solid #cccccc;
    border-radius: 5px;
    font-family: 'Atkinson Hyperlegible Mono', sans-serif;
    background-color: white;
}

.control-group input[type="number"] {
    width: 120px;
}

.btn-primary {
    padding: 10px 24px;
    font-size: 15px;
    font-weight: bold;
    background-color: #007bff;
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-family: 'Atkinson Hyperlegible Mono', sans-serif;
}

.btn-primary:hover {
    background-color: #0056b3;
}

.data-status {
    font-size: 13px;
    color: #555;
}

.exercise-container {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.exercise-card {
    background-color: white;
    border-radius: 10px;
    padding: 16px;
    box-shadow: 0 1px 6px rgba(0, 0, 0, 0.08);
    border-left: 5px solid #007bff;
}

.exercise-title {
    margin: 0 0 8px 0;
    font-size: 14px;
    color: #666;
}

.exercise-sentence {
    margin: 0 0 12px 0;
    font-size: 20px;
    line-height: 1.4;
}

.exercise-blank {
    display: inline-block;
    min-width: 88px;
    padding: 0 8px;
    border-bottom: 3px solid #007bff;
    text-align: center;
    font-weight: bold;
}

.choice-row {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.choice-btn {
    padding: 8px 14px;
    border: 1px solid #007bff;
    border-radius: 20px;
    background: white;
    color: #007bff;
    cursor: pointer;
    font-weight: bold;
    font-family: inherit;
}

.choice-btn:hover {
    background: #e7f1ff;
}

.choice-btn.correct {
    background: #2e7d32;
    border-color: #2e7d32;
    color: white;
}

.choice-btn.wrong {
    background: #c62828;
    border-color: #c62828;
    color: white;
}

.choice-btn:disabled {
    cursor: default;
    opacity: 0.9;
}

.feedback {
    margin-top: 10px;
    padding: 10px 12px;
    border-radius: 6px;
    font-size: 14px;
}

.feedback.ok {
    background: #e8f5e9;
    color: #1b5e20;
    border: 1px solid #a5d6a7;
}

.feedback.bad {
    background: #ffebee;
    color: #b71c1c;
    border: 1px solid #ef9a9a;
}

footer {
    font-size: 14px;
    color: #666666;
    margin: 24px 0;
    text-align: center;
}