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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
    min-height: 100vh;
    padding: 250px 20px 20px;
}

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

.header {
    background: white;
    padding: 20px 25px; 
    margin-bottom: 25px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: fixed; 
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    max-width: 1200px;
    width: calc(100% - 40px);
    z-index: 100;
    transition: transform 0.3s ease-out, box-shadow 0.3s ease; 
    border-radius: 0 0 15px 15px;
}

.header.scrolled {
    transform: translateY(-110px) translateX(-50%); 
    box-shadow: 0 2px 15px rgba(0,0,0,0.15);
    padding: 20px 25px; 
}

.header-content {
    transition: opacity 0.3s ease, transform 0.3s ease;
    opacity: 1;
}

.header.scrolled .header-content {
    opacity: 0; 
    transform: translateY(-20px);
}


.header h1 {
    color: #667eea;
    font-size: 2em;
    margin-bottom: 15px;
    text-align: center;
}

.controls {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
}

.search-box {
    flex: 1;
    min-width: 250px;
    position: relative;
}

.search-box input {
    width: 100%;
    padding: 12px 40px 12px 15px;
    border: 2px solid #e0e0e0;
    border-radius: 10px;
    font-size: 16px;
    transition: all 0.3s;
}

.search-box input:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.search-icon {
    position: absolute;
    right: 15px;
    top: 50%;
    transform: translateY(-50%);
    color: #999;
}

.filter-btn {
    padding: 12px 25px;
    background: #667eea;
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.3s;
    display: flex;
    align-items: center;
    gap: 8px;
}

.filter-btn:hover {
    background: #5568d3;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.3);
}

.stats {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-top: 15px;
    flex-wrap: wrap;
    transition: margin 0.3s ease;
}

.header.scrolled .stats {
    margin-top: 0;
}

.stat-item {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 12px 25px;
    border-radius: 10px;
    text-align: center;
}

.stat-item .number {
    font-size: 22px;
    font-weight: bold;
}

.stat-item .label {
    font-size: 13px;
    opacity: 0.9;
}

#questionContainer {
    display: grid;
    gap: 30px;
}

.question-card {
    background: white;
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.1);
    transition: box-shadow 0.3s ease;
    will-change: box-shadow;
}

.question-card:hover {
    box-shadow: 0 15px 50px rgba(0,0,0,0.15);
}

.question-card.fade-in {
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.question-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 2px solid #f0f0f0;
    flex-wrap: wrap;
    gap: 10px;
}

.question-number {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 8px 20px;
    border-radius: 20px;
    font-weight: bold;
}

.question-status {
    display: flex;
    gap: 10px;
    align-items: center;
}

.status-badge {
    padding: 6px 15px;
    border-radius: 15px;
    font-size: 14px;
    font-weight: bold;
}

.status-badge.correct {
    background: #e8f5e9;
    color: #4caf50;
}

.status-badge.wrong {
    background: #ffebee;
    color: #f44336;
}

.question-text {
    font-size: 18px;
    line-height: 1.8;
    color: #333;
    margin-bottom: 25px;
}

.question-image {
    margin: 25px 0;
    text-align: center;
}

.question-image img {
    max-width: 100%;
    max-height: 400px;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    object-fit: contain;
}

.options {
    display: grid;
    gap: 15px;
    margin: 25px 0;
}

.option {
    padding: 18px 25px;
    border: 2px solid #e0e0e0;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 15px;
    -webkit-tap-highlight-color: transparent;
    user-select: none;
}

.option:hover {
    border-color: #667eea;
    background: #f8f9ff;
}

.option:active {
    transform: scale(0.98);
}

.option.selected {
    border-color: #667eea;
    background: #f0f3ff;
}

.option.correct {
    border-color: #4caf50;
    background: #e8f5e9;
    animation: correctPulse 0.5s ease;
}

.option.wrong {
    border-color: #f44336;
    background: #ffebee;
    animation: wrongShake 0.5s ease;
}

@keyframes correctPulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.02); }
}

@keyframes wrongShake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

.option-label {
    width: 35px;
    height: 35px;
    border-radius: 50%;
    background: #667eea;
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    flex-shrink: 0;
}

.option.correct .option-label {
    background: #4caf50;
}

.option.wrong .option-label {
    background: #f44336;
}

.option-text {
    flex: 1;
    font-size: 16px;
}

.option-end-note {
    margin-top: 15px;
    padding-left: 5px;
    font-size: 15px;
    color: #666;
    text-align: left;
}

.button-group {
    display: flex;
    gap: 15px;
    margin-top: 30px;
    flex-wrap: wrap;
}

.btn {
    flex: 1;
    min-width: 120px;
    padding: 15px 30px;
    border: none;
    border-radius: 12px;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background: #f0f0f0;
    color: #333;
}

.btn-secondary:hover:not(:disabled) {
    background: #e0e0e0;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.explain-box {
    background: #fff9e6;
    border-left: 4px solid #ffc107;
    padding: 20px;
    margin-top: 20px;
    border-radius: 10px;
    display: none;
}

.explain-box.show {
    display: block;
    animation: slideIn 0.5s ease;
}

.explain-title {
    font-weight: bold;
    color: #f57c00;
    margin-bottom: 10px;
}

.no-questions {
    text-align: center;
    padding: 60px 20px;
    background: white;
    border-radius: 20px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.1);
}

.no-questions h2 {
    color: #667eea;
    margin-bottom: 10px;
}

.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.5);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.show {
    display: flex;
}

.modal-content {
    background: white;
    padding: 40px;
    border-radius: 20px;
    max-width: 500px;
    width: 90%;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
    animation: slideIn 0.3s ease;
}

.modal-content h2 {
    color: #667eea;
    margin-bottom: 20px;
}

.filter-options {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.filter-option {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px;
    border-radius: 8px;
    transition: background 0.2s;
}

.filter-option:hover {
    background: #f8f9ff;
}

.filter-option input[type="radio"],
.filter-option input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

.filter-option label {
    cursor: pointer;
    flex: 1;
}


@media (max-width: 1024px) {
    .container {
        max-width: 100%;
    }
}


/* === 手機與平板通用 (max-width: 768px) === */
@media (max-width: 768px) {
    body {
        padding: 280px 0 0 0;
        width: 100%;
    }

    .container {
        padding: 0;
    }

    .header {
        left: 50%;
        transform: translateX(-50%);
        width: 100%;
        max-width: calc(100% - 20px);
        padding: 15px;
        border-radius: 0 0 15px 15px;
        transition: transform 0.3s ease, padding 0.3s ease;
    }

    .header.scrolled {
        transform: translate(-50%, -130px);
        padding: 10px 15px;
    }

    .header h1 {
        font-size: 1.5em;
        margin-bottom: 15px;
    }

    .controls {
        flex-direction: column;
        width: 100%;
        gap: 10px;
    }

    .search-box,
    .filter-btn {
        width: 100%;
    }

    .filter-btn {
        justify-content: center;
    }

    .stats {
        display: flex;
        flex-wrap: wrap;
        gap: 8px;
        margin-top: 15px;
    }

    .stat-item {
        flex: 1;
        min-width: 0;
        padding: 12px 10px;
        text-align: center;
    }

    .stat-item .number {
        font-size: 20px;
    }

    .stat-item .label {
        font-size: 12px;
    }

    #questionContainer {
        gap: 20px;
        padding: 0 10px 20px;
    }

    .question-card {
        padding: 20px 15px;
        border-radius: 15px;
        transition: transform 0.2s ease;
    }

    .question-card:hover {
        transform: none;
    }

    .question-header {
        display: flex;
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }

    .question-number {
        font-size: 14px;
        padding: 6px 15px;
    }

    .question-text {
        font-size: 16px;
        line-height: 1.6;
        word-break: break-word;
    }

    .question-image img {
        max-height: 300px;
        width: 100%;
        object-fit: contain;
    }

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

    .option {
        display: flex;
        align-items: center;
        padding: 15px;
        transition: transform 0.2s ease;
    }

    .option:hover {
        transform: none;
    }

    .option:active {
        transform: scale(0.98);
    }

    .option-label {
        width: 32px;
        height: 32px;
        font-size: 14px;
        display: flex;
        align-items: center;
        justify-content: center;
        border-radius: 50%;
        flex-shrink: 0;
    }

    .option-text {
        font-size: 15px;
        word-break: break-word;
        flex: 1;
    }

    .button-group {
        display: flex;
        flex-direction: column;
        gap: 10px;
        margin-top: 20px;
    }

    .btn {
        width: 100%;
        padding: 12px 20px;
        font-size: 15px;
    }

    .explain-box {
        padding: 15px;
        font-size: 14px;
        margin-top: 15px;
    }

    .modal-content {
        width: 95%;
        padding: 25px 20px;
        margin: 10px auto;
    }

    .modal-content h2 {
        font-size: 1.3em;
    }

    .filter-options {
        display: flex;
        flex-direction: column;
        gap: 12px;
    }

    .filter-option {
        padding: 12px 10px;
    }

    .filter-option label {
        font-size: 15px;
    }
}

/* === 小螢幕手機 (max-width: 480px) === */
/* @media (max-width: 480px) {

    .header h1 {
        font-size: 1.3em;
    }

    .question-card {
        padding: 15px 12px;
    }

    .question-text {
        font-size: 15px;
    }

    .option {
        padding: 12px;
    }

    .option-label {
        width: 28px;
        height: 28px;
        font-size: 13px;
    }

    .option-text {
        font-size: 14px;
    }

    .btn {
        padding: 10px 15px;
        font-size: 14px;
    }

    .stat-item .number {
        font-size: 18px;
    }

    .stat-item .label {
        font-size: 11px;
    }
} */