/* =============================================
   "현대사회와 AI활용" 2학기 교양 시험 디자인 시스템
   ============================================= */

:root {
    --bg-dark: #0f172a;
    --surface: #1e293b;
    --surface-hover: #334155;
    --border: #334155;
    --primary: #8b5cf6;
    --primary-gradient: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
    --emerald: #10b981;
    --red: #ef4444;
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
    --radius: 16px;
}

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

body {
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-main);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    line-height: 1.6;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 24px 16px;
    width: 100%;
}

/* 헤더 */
.site-header {
    text-align: center;
    padding: 32px 0 24px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 32px;
}

.site-badge {
    display: inline-block;
    padding: 6px 16px;
    background: rgba(139, 92, 246, 0.15);
    color: #a78bfa;
    border: 1px solid rgba(139, 92, 246, 0.3);
    border-radius: 999px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 12px;
}

.site-header h1 {
    font-size: 2.2rem;
    font-weight: 800;
    background: linear-gradient(135deg, #ffffff 0%, #cbd5e1 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 8px;
}

.site-header p {
    color: var(--text-muted);
    font-size: 1rem;
}

/* 카드 및 메뉴 */
.grid-menu {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
    margin-bottom: 40px;
}

.menu-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    transition: all 0.25s ease;
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.menu-card:hover {
    transform: translateY(-4px);
    border-color: var(--primary);
    box-shadow: 0 12px 30px rgba(139, 92, 246, 0.2);
}

.card-icon {
    font-size: 2.4rem;
    margin-bottom: 16px;
}

.card-title {
    font-size: 1.35rem;
    font-weight: 700;
    margin-bottom: 8px;
}

.card-desc {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: 20px;
}

.btn-start {
    display: inline-block;
    width: 100%;
    text-align: center;
    padding: 14px;
    background: var(--primary-gradient);
    color: #fff;
    font-weight: 700;
    border-radius: 12px;
    text-decoration: none;
    border: none;
    cursor: pointer;
    font-size: 1rem;
    box-shadow: 0 4px 14px rgba(139, 92, 246, 0.4);
    transition: opacity 0.2s;
}

.btn-start:hover {
    opacity: 0.9;
}

/* 인증 폼 모달 / 박스 */
.auth-box {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    max-width: 520px;
    margin: 40px auto;
    box-shadow: var(--shadow);
}

.auth-box h2 {
    font-size: 1.5rem;
    margin-bottom: 8px;
    text-align: center;
}

.auth-box p {
    color: var(--text-muted);
    font-size: 0.9rem;
    text-align: center;
    margin-bottom: 24px;
}

.form-group {
    margin-bottom: 18px;
}

.form-group label {
    display: block;
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 6px;
    color: var(--text-main);
}

.form-control {
    width: 100%;
    padding: 14px;
    background: #0f172a;
    border: 1px solid var(--border);
    border-radius: 10px;
    color: #fff;
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s;
}

.form-control:focus {
    border-color: var(--primary);
}

/* 시험 영역 */
.exam-header-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px 24px;
    margin-bottom: 24px;
}

.timer-badge {
    background: rgba(239, 68, 68, 0.15);
    color: #fca5a5;
    border: 1px solid rgba(239, 68, 68, 0.3);
    padding: 6px 16px;
    border-radius: 999px;
    font-weight: 700;
    font-size: 1.1rem;
}

.tab-warning-badge {
    background: rgba(245, 158, 11, 0.15);
    color: #fcd34d;
    border: 1px solid rgba(245, 158, 11, 0.3);
    padding: 6px 14px;
    border-radius: 999px;
    font-size: 0.85rem;
    font-weight: 600;
}

.question-box {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    margin-bottom: 24px;
}

.question-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 24px;
    line-height: 1.5;
}

.choice-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.choice-item {
    background: #0f172a;
    border: 1.5px solid var(--border);
    border-radius: 12px;
    padding: 16px 20px;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 12px;
}

.choice-item:hover {
    border-color: var(--primary);
    background: rgba(139, 92, 246, 0.05);
}

.choice-item.selected {
    border-color: var(--primary);
    background: rgba(139, 92, 246, 0.15);
    font-weight: 600;
}

.choice-num {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--surface-hover);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.85rem;
    font-weight: 700;
}

.choice-item.selected .choice-num {
    background: var(--primary);
    color: #fff;
}

/* 문제 연습(Practice) 모드 즉시 채점 스타일 */
.choice-item.correct {
    border-color: #10b981 !important;
    background: rgba(16, 185, 129, 0.15) !important;
}
.choice-item.correct .choice-num {
    background: #10b981 !important;
    color: #fff !important;
}

.choice-item.wrong {
    border-color: #ef4444 !important;
    background: rgba(239, 68, 68, 0.15) !important;
}
.choice-item.wrong .choice-num {
    background: #ef4444 !important;
    color: #fff !important;
}

.explanation-box {
    margin-top: 20px;
    padding: 16px 20px;
    border-radius: 12px;
    background: rgba(16, 185, 129, 0.08);
    border: 1px solid rgba(16, 185, 129, 0.25);
    font-size: 0.95rem;
    line-height: 1.6;
    animation: fadeIn 0.25s ease-in;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-4px); }
    to { opacity: 1; transform: translateY(0); }
}

.exam-nav {
    display: flex;
    justify-content: space-between;
    margin-top: 24px;
}

.btn-secondary {
    background: var(--surface-hover);
    color: #fff;
    border: 1px solid var(--border);
    padding: 12px 24px;
    border-radius: 10px;
    cursor: pointer;
    font-weight: 600;
}

/* =============================================
   🏆 위변조 방지 보안 성적표 카운터/카드 (다운로드용)
   ============================================= */
.cert-modal-backdrop {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(0, 0, 0, 0.85);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    padding: 20px;
    overflow-y: auto;
}

/* 다운로드되는 실제 캔버스 영역 */
.security-cert-card {
    position: relative;
    width: 650px;
    background: #0f172a;
    border: 8px solid #334155;
    border-radius: 20px;
    padding: 40px 36px;
    color: #f8fafc;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.8);
    overflow: hidden;
}

/* 워터마크 배경 오버레이 */
.cert-watermark-overlay {
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    pointer-events: none;
    z-index: 1;
    opacity: 0.08;
    transform: rotate(-25deg);
    display: flex;
    flex-wrap: wrap;
    align-content: flex-start;
    gap: 30px 40px;
    font-size: 0.9rem;
    font-weight: 800;
    color: #cbd5e1;
    user-select: none;
}

.cert-content {
    position: relative;
    z-index: 2;
}

.cert-header {
    text-align: center;
    border-bottom: 2px dashed rgba(255, 255, 255, 0.2);
    padding-bottom: 20px;
    margin-bottom: 28px;
}

.cert-title-badge {
    display: inline-block;
    background: linear-gradient(135deg, #8b5cf6, #6366f1);
    color: #fff;
    font-size: 0.8rem;
    font-weight: 800;
    padding: 4px 14px;
    border-radius: 999px;
    letter-spacing: 1px;
    margin-bottom: 10px;
}

.cert-header h2 {
    font-size: 1.8rem;
    font-weight: 800;
    color: #ffffff;
    letter-spacing: -0.5px;
}

.cert-info-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    background: rgba(30, 41, 59, 0.7);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 24px;
}

.cert-info-item {
    font-size: 0.95rem;
}

.cert-info-label {
    color: var(--text-muted);
    font-size: 0.85rem;
    display: block;
    margin-bottom: 2px;
}

.cert-info-value {
    font-weight: 700;
    color: #f8fafc;
}

.cert-score-box {
    text-align: center;
    background: linear-gradient(135deg, rgba(139, 92, 246, 0.2) 0%, rgba(16, 185, 129, 0.2) 100%);
    border: 2px solid #8b5cf6;
    border-radius: 16px;
    padding: 24px;
    margin-bottom: 24px;
}

.cert-score-number {
    font-size: 3.2rem;
    font-weight: 900;
    color: #10b981;
    line-height: 1;
    margin-bottom: 8px;
}

.cert-score-sub {
    font-size: 0.9rem;
    color: var(--text-muted);
}

.cert-footer {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 18px;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.cert-hash {
    font-family: monospace;
    font-size: 0.78rem;
    color: #a78bfa;
}

.stamp-seal {
    width: 65px;
    height: 65px;
    border: 3px double #ef4444;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #ef4444;
    font-weight: 900;
    font-size: 0.75rem;
    transform: rotate(-12deg);
    text-align: center;
    line-height: 1.1;
}

/* 다운로드 컨트롤 버튼 바 */
.cert-btn-bar {
    margin-top: 20px;
    display: flex;
    gap: 12px;
    justify-content: center;
}

.btn-download {
    background: #10b981;
    color: #fff;
    border: none;
    padding: 14px 28px;
    border-radius: 12px;
    font-weight: 700;
    font-size: 1rem;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(16, 185, 129, 0.4);
}

.btn-download:hover {
    background: #059669;
}

/* =============================================
   📱 모바일 디바이스 반응형 스타일 (화면폭 768px 이하)
   ============================================= */
@media (max-width: 768px) {
    .container {
        padding: 16px 12px;
    }

    /* 그리드 레이아웃 1열로 변경 */
    #exam-layout-grid {
        grid-template-columns: 1fr !important;
        gap: 16px !important;
    }

    /* 시험 헤더 바 세로 배치 */
    .exam-header-bar {
        flex-direction: column;
        gap: 12px;
        align-items: flex-start;
        padding: 14px 16px;
    }

    .timer-badge {
        width: 100%;
        text-align: center;
        font-size: 1rem;
    }

    .tab-warning-badge {
        font-size: 0.8rem;
    }

    /* 문제 카드 내부 여백 조정 */
    .question-box {
        padding: 20px 16px;
    }

    .question-title {
        font-size: 1.1rem;
        line-height: 1.5;
        margin-bottom: 18px;
    }

    .choice-item {
        padding: 14px 16px;
        font-size: 0.95rem;
    }

    .choice-badge {
        width: 28px;
        height: 28px;
        font-size: 0.85rem;
    }

    /* 하단 이동 버튼 */
    .exam-nav {
        flex-direction: row;
        gap: 8px;
    }

    .exam-nav button {
        flex: 1;
        padding: 12px 14px !important;
        font-size: 0.95rem;
    }

    /* OMR 답안지 모바일 축소 (실제 시험 시) */
    #omr-grid {
        grid-template-columns: repeat(5, 1fr) !important;
        gap: 6px !important;
    }

    .omr-btn {
        padding: 8px 4px;
        font-size: 0.85rem;
    }

    /* 인증 폼 모바일 여백 */
    .auth-box {
        padding: 24px 16px;
        margin: 16px auto;
    }

    /* 모달 및 성적표 모바일 대응 */
    .security-cert-card {
        padding: 24px 16px;
        max-width: 95vw;
    }

    .cert-title {
        font-size: 1.25rem !important;
    }

    .cert-info-grid {
        grid-template-columns: 1fr !important;
        gap: 8px;
    }

    .cert-score-number {
        font-size: 2.5rem;
    }
}