/* ===========================
   큐뇌 문제은행 - Design System
   =========================== */

/* CSS 변수 (브랜드 컬러 시스템) */
:root {
    --primary: #4f46e5;
    --primary-dark: #4338ca;
    --primary-light: #818cf8;
    --primary-50: #eef2ff;
    --primary-100: #e0e7ff;
    --secondary: #0ea5e9;
    --secondary-dark: #0284c7;
    --accent: #f59e0b;
    --accent-dark: #d97706;
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --info: #06b6d4;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --radius-sm: 6px;
    --radius: 10px;
    --radius-lg: 16px;
    --radius-xl: 20px;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 10px 10px -5px rgba(0,0,0,0.04);
    --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --font-sans: 'Pretendard', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Noto Sans KR', sans-serif;
}

/* 전역 기본 */
* { box-sizing: border-box; }

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background-color: var(--gray-50);
    font-family: var(--font-sans);
    color: var(--gray-800);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

main { flex: 1; }

h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    color: var(--gray-900);
    line-height: 1.3;
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: color var(--transition);
}

a:hover { color: var(--primary-dark); }

/* ===========================
   네비게이션
   =========================== */
.navbar {
    background: #fff !important;
    box-shadow: var(--shadow);
    padding: 0.6rem 0;
    border-bottom: none;
    backdrop-filter: blur(10px);
    transition: box-shadow var(--transition);
}

.navbar-brand {
    font-weight: 800;
    font-size: 1.35rem;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.02em;
}

.navbar-brand img { max-height: 36px; }

.navbar .nav-link {
    font-weight: 500;
    color: var(--gray-600) !important;
    padding: 0.5rem 1rem !important;
    border-radius: var(--radius-sm);
    transition: all var(--transition);
    font-size: 0.95rem;
}

.navbar .nav-link:hover {
    color: var(--primary) !important;
    background-color: var(--primary-50);
}

.navbar .form-control {
    border-radius: 50px;
    border: 1.5px solid var(--gray-200);
    padding: 0.45rem 1rem;
    font-size: 0.9rem;
    background-color: var(--gray-50);
    transition: all var(--transition);
}

.navbar .form-control:focus {
    border-color: var(--primary-light);
    box-shadow: 0 0 0 3px rgba(79,70,229,0.1);
    background-color: #fff;
}

.navbar .btn-outline-primary {
    border-radius: 50px;
    border-color: var(--primary);
    color: var(--primary);
    font-weight: 500;
    font-size: 0.9rem;
    padding: 0.45rem 1.2rem;
}

.navbar .btn-outline-primary:hover {
    background-color: var(--primary);
    border-color: var(--primary);
    color: #fff;
}

/* ===========================
   카드
   =========================== */
.card {
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition), box-shadow var(--transition);
    overflow: hidden;
    background: #fff;
}

.card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.card-header {
    border-bottom: 1px solid var(--gray-100);
    font-weight: 600;
    padding: 1rem 1.25rem;
    background-color: transparent;
}

.card-header.bg-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark)) !important;
    border-bottom: none;
}

.card-header.bg-success {
    background: linear-gradient(135deg, var(--success), #059669) !important;
    border-bottom: none;
}

.card-header.bg-warning {
    background: linear-gradient(135deg, var(--accent), var(--accent-dark)) !important;
    border-bottom: none;
}

.card-header.bg-info {
    background: linear-gradient(135deg, var(--info), #0891b2) !important;
    border-bottom: none;
}

.card-body { padding: 1.25rem; }

.card-title {
    color: var(--gray-800);
    font-weight: 600;
    font-size: 1rem;
}

/* 카드 내 중첩 카드 호버 억제 */
.card .card { border: 1px solid var(--gray-100); }
.card .card:hover { transform: none; box-shadow: var(--shadow-sm); }

/* ===========================
   버튼
   =========================== */
.btn {
    font-weight: 500;
    border-radius: var(--radius);
    padding: 0.5rem 1.25rem;
    transition: all var(--transition);
    font-size: 0.925rem;
    letter-spacing: -0.01em;
}

.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0); }

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    border: none;
    box-shadow: 0 2px 4px rgba(79,70,229,0.3);
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-dark), #3730a3);
    box-shadow: 0 4px 8px rgba(79,70,229,0.4);
}

.btn-outline-primary {
    color: var(--primary);
    border: 1.5px solid var(--primary);
    background: transparent;
}

.btn-outline-primary:hover {
    background: var(--primary);
    border-color: var(--primary);
    color: #fff;
}

.btn-success {
    background: linear-gradient(135deg, var(--success), #059669);
    border: none;
}

.btn-danger {
    background: linear-gradient(135deg, var(--danger), #dc2626);
    border: none;
}

.btn-warning {
    background: linear-gradient(135deg, var(--accent), var(--accent-dark));
    border: none;
    color: #fff;
}

.btn-warning:hover { color: #fff; }

.btn-light {
    background: #fff;
    border: 1px solid var(--gray-200);
    color: var(--gray-700);
}

.btn-light:hover {
    background: var(--gray-50);
    border-color: var(--gray-300);
}

.btn-lg {
    padding: 0.75rem 1.75rem;
    font-size: 1.05rem;
    border-radius: var(--radius-lg);
}

.btn-sm {
    padding: 0.35rem 0.85rem;
    font-size: 0.825rem;
    border-radius: var(--radius-sm);
}

/* ===========================
   히어로 섹션
   =========================== */
.hero-section {
    background: linear-gradient(135deg, var(--primary) 0%, #7c3aed 50%, var(--secondary) 100%);
    position: relative;
    overflow: hidden;
    border-radius: 0 0 var(--radius-xl) var(--radius-xl);
    margin: -1rem -12px 0;
    padding: 3.5rem 0;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: radial-gradient(circle at 30% 50%, rgba(255,255,255,0.15) 0%, transparent 50%),
                radial-gradient(circle at 70% 80%, rgba(255,255,255,0.1) 0%, transparent 40%);
}

.hero-section::after {
    content: '';
    position: absolute;
    top: -50%; left: -50%;
    width: 200%; height: 200%;
    background: repeating-linear-gradient(
        45deg,
        transparent,
        transparent 20px,
        rgba(255,255,255,0.02) 20px,
        rgba(255,255,255,0.02) 40px
    );
    animation: subtleMove 30s linear infinite;
}

@keyframes subtleMove {
    from { transform: translate(0,0); }
    to { transform: translate(40px, 40px); }
}

.hero-section .container {
    position: relative;
    z-index: 2;
}

.hero-section h1 {
    font-size: 2.5rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    color: #fff;
    text-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.hero-section .lead {
    font-size: 1.15rem;
    opacity: 0.9;
    font-weight: 400;
}

.hero-section .btn-light {
    background: #fff;
    color: var(--primary);
    border: none;
    font-weight: 600;
    box-shadow: 0 4px 14px rgba(0,0,0,0.15);
}

.hero-section .btn-light:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.2);
}

.hero-section .btn-outline-light {
    border: 2px solid rgba(255,255,255,0.6);
    color: #fff;
    font-weight: 600;
}

.hero-section .btn-outline-light:hover {
    background: rgba(255,255,255,0.15);
    border-color: #fff;
}

/* ===========================
   검색 폼 (홈)
   =========================== */
.search-card .form-control-lg,
.search-card .form-select-lg {
    border-radius: var(--radius);
    border: 1.5px solid var(--gray-200);
    padding: 0.75rem 1rem;
}

.search-card .form-control-lg:focus,
.search-card .form-select-lg:focus {
    border-color: var(--primary-light);
    box-shadow: 0 0 0 3px rgba(79,70,229,0.1);
}

/* ===========================
   아코디언
   =========================== */
.accordion-item {
    border: none;
    border-bottom: 1px solid var(--gray-100);
}

.accordion-item:last-child { border-bottom: none; }

.accordion-button {
    font-weight: 500;
    font-size: 0.95rem;
    color: var(--gray-700);
    padding: 0.85rem 1.25rem;
    background: transparent;
}

.accordion-button:not(.collapsed) {
    background-color: var(--primary-50);
    color: var(--primary);
    box-shadow: none;
    font-weight: 600;
}

.accordion-button:focus {
    box-shadow: 0 0 0 3px rgba(79,70,229,0.15);
}

.accordion-button::after {
    width: 1rem;
    height: 1rem;
    background-size: 1rem;
}

/* ===========================
   리스트 그룹
   =========================== */
.list-group-item {
    border-left: none;
    border-right: none;
    padding: 0.85rem 1.25rem;
    transition: background-color var(--transition);
    font-size: 0.925rem;
}

.list-group-item:first-child { border-top: none; }
.list-group-item:last-child { border-bottom: none; }

.list-group-item-action:hover {
    background-color: var(--primary-50);
    color: var(--primary);
}

.list-group-item.active {
    background-color: var(--primary);
    border-color: var(--primary);
    color: #fff;
}

/* ===========================
   배지
   =========================== */
.badge {
    font-weight: 500;
    padding: 0.4em 0.75em;
    border-radius: 50px;
    font-size: 0.775rem;
    letter-spacing: 0.01em;
}

.badge.bg-primary { background-color: var(--primary) !important; }
.badge.bg-success { background-color: var(--success) !important; }
.badge.bg-danger { background-color: var(--danger) !important; }
.badge.bg-warning { background-color: var(--accent) !important; color: #fff !important; }
.badge.bg-info { background-color: var(--info) !important; }
.badge.bg-secondary { background-color: var(--gray-500) !important; }

/* ===========================
   폼 요소
   =========================== */
.form-control {
    border-radius: var(--radius);
    border: 1.5px solid var(--gray-200);
    padding: 0.6rem 0.9rem;
    transition: all var(--transition);
    font-size: 0.925rem;
}

.form-control:focus {
    border-color: var(--primary-light);
    box-shadow: 0 0 0 3px rgba(79,70,229,0.1);
}

.form-select {
    border-radius: var(--radius);
    border: 1.5px solid var(--gray-200);
    padding: 0.6rem 0.9rem;
}

.form-select:focus {
    border-color: var(--primary-light);
    box-shadow: 0 0 0 3px rgba(79,70,229,0.1);
}

.form-check-input:checked {
    background-color: var(--primary);
    border-color: var(--primary);
}

/* ===========================
   알림
   =========================== */
.alert {
    border-radius: var(--radius);
    border: none;
    font-size: 0.925rem;
}

.alert-success {
    background-color: #ecfdf5;
    color: #065f46;
    border-left: 4px solid var(--success);
}

.alert-danger {
    background-color: #fef2f2;
    color: #991b1b;
    border-left: 4px solid var(--danger);
}

.alert-info {
    background-color: #ecfeff;
    color: #155e75;
    border-left: 4px solid var(--info);
}

.alert-warning {
    background-color: #fffbeb;
    color: #92400e;
    border-left: 4px solid var(--accent);
}

/* ===========================
   모달
   =========================== */
.modal-content {
    border: none;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
}

.modal-header {
    border-bottom: 1px solid var(--gray-100);
    padding: 1.25rem 1.5rem;
}

.modal-footer {
    border-top: 1px solid var(--gray-100);
    padding: 1rem 1.5rem;
}

/* ===========================
   푸터
   =========================== */
.footer {
    background: var(--gray-800) !important;
    color: var(--gray-300);
    border-top: none;
    padding: 3rem 0 1.5rem;
}

.footer h5 {
    color: #fff;
    font-weight: 700;
    font-size: 1.05rem;
    margin-bottom: 1rem;
}

.footer p { color: var(--gray-400); font-size: 0.9rem; }

.footer a {
    color: var(--gray-400);
    text-decoration: none;
    transition: color var(--transition);
    font-size: 0.9rem;
}

.footer a:hover { color: #fff; }

.footer hr {
    border-color: var(--gray-600);
    margin: 2rem 0 1rem;
}

.footer .text-center p {
    color: var(--gray-500);
    font-size: 0.85rem;
}

.footer ul li { margin-bottom: 0.5rem; }

/* ===========================
   드롭다운
   =========================== */
.dropdown-menu {
    display: none !important;
    position: absolute !important;
    z-index: 99999 !important;
    min-width: 12rem !important;
    padding: 0.5rem !important;
    border: 1px solid var(--gray-200) !important;
    border-radius: var(--radius) !important;
    box-shadow: var(--shadow-lg) !important;
    background-color: #fff !important;
    top: 100% !important;
    left: 0 !important;
    animation: dropdownFade 0.15s ease;
}

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

.dropdown-menu.show { display: block !important; }

.dropdown-menu-end {
    right: 0 !important;
    left: auto !important;
}

.dropdown-item {
    display: block;
    width: 100%;
    padding: 0.5rem 0.85rem;
    font-weight: 400;
    font-size: 0.9rem;
    color: var(--gray-700);
    text-decoration: none;
    white-space: nowrap;
    background-color: transparent;
    border: 0;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition);
}

.dropdown-item:hover {
    color: var(--primary);
    background-color: var(--primary-50);
}

.dropdown-item:active {
    color: #fff;
    background-color: var(--primary);
}

.dropdown-divider {
    margin: 0.35rem 0;
    border-top: 1px solid var(--gray-100);
}

.dropdown-toggle::after {
    display: inline-block;
    margin-left: 0.3em;
    vertical-align: 0.2em;
    content: "";
    border-top: 0.28em solid;
    border-right: 0.28em solid transparent;
    border-bottom: 0;
    border-left: 0.28em solid transparent;
    opacity: 0.6;
}

/* ===========================
   테이블
   =========================== */
.table {
    font-size: 0.925rem;
}

.table thead th {
    font-weight: 600;
    color: var(--gray-600);
    text-transform: uppercase;
    font-size: 0.8rem;
    letter-spacing: 0.03em;
    border-bottom: 2px solid var(--gray-200);
    padding: 0.85rem;
}

.table tbody td {
    padding: 0.85rem;
    vertical-align: middle;
    border-color: var(--gray-100);
}

.table-hover tbody tr:hover {
    background-color: var(--primary-50);
}

/* ===========================
   페이지네이션
   =========================== */
.pagination .page-link {
    border-radius: var(--radius-sm);
    margin: 0 2px;
    border: 1px solid var(--gray-200);
    color: var(--gray-600);
    font-weight: 500;
    font-size: 0.9rem;
    padding: 0.45rem 0.85rem;
    transition: all var(--transition);
}

.pagination .page-link:hover {
    background-color: var(--primary-50);
    color: var(--primary);
    border-color: var(--primary-light);
}

.pagination .page-item.active .page-link {
    background-color: var(--primary);
    border-color: var(--primary);
}

/* ===========================
   프로그레스 바
   =========================== */
.progress {
    border-radius: 50px;
    background-color: var(--gray-100);
    height: 8px;
}

.progress-bar {
    border-radius: 50px;
}

.progress-bar.bg-success { background-color: var(--success) !important; }
.progress-bar.bg-warning { background-color: var(--accent) !important; }
.progress-bar.bg-danger { background-color: var(--danger) !important; }

/* ===========================
   마이페이지 사이드바
   =========================== */
.col-md-3 > .card .list-group-item i {
    width: 20px;
    text-align: center;
    margin-right: 0.5rem;
    font-size: 0.9rem;
}

/* ===========================
   문제 풀이 페이지
   =========================== */
.option-item {
    transition: all var(--transition);
    cursor: pointer;
    display: flex;
    align-items: center;
    padding: 14px 16px;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius);
    background: #fff;
    margin-bottom: 10px;
}

.option-item:hover {
    transform: translateX(4px);
    background-color: var(--primary-50) !important;
    border-color: var(--primary-light);
}

.option-item.selected {
    border-color: var(--primary);
    background-color: var(--primary-50);
}

.option-item.correct {
    border-color: var(--success);
    background-color: #ecfdf5;
}

.option-item.incorrect {
    border-color: var(--danger);
    background-color: #fef2f2;
}

.option-content {
    display: flex;
    align-items: center;
    width: 100%;
}

.option-number {
    background: var(--gray-500);
    color: white;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-right: 14px;
    font-weight: 700;
    font-size: 0.85rem;
    flex-shrink: 0;
}

.option-item.selected .option-number { background: var(--primary); }
.option-item.correct .option-number { background: var(--success); }
.option-item.incorrect .option-number { background: var(--danger); }

.option-text { flex: 1; font-size: 0.975rem; }

.answer-radio { display: none; }

.question-content {
    font-size: 1.05rem;
    line-height: 1.7;
}

.explanation-content {
    background: var(--gray-50);
    border-radius: var(--radius);
    padding: 1.25rem;
    min-height: 100px;
    border: 1px solid var(--gray-100);
}

/* ===========================
   Jumbotron (exam/index)
   =========================== */
.jumbotron {
    background: linear-gradient(135deg, var(--primary) 0%, #7c3aed 100%);
    border-radius: var(--radius-xl);
    padding: 2.5rem;
}

/* ===========================
   통계 카드 (홈/마이페이지)
   =========================== */
.border.rounded {
    border-radius: var(--radius) !important;
    border-color: var(--gray-200) !important;
    transition: all var(--transition);
    background: #fff;
}

.border.rounded:hover {
    background-color: var(--primary-50);
    border-color: var(--primary-light) !important;
    transform: translateY(-2px);
}

/* ===========================
   소셜 로그인 버튼
   =========================== */
.btn-naver {
    background-color: #03c75a;
    border-color: #03c75a;
    color: #fff;
}

.btn-naver:hover {
    background-color: #02b351;
    border-color: #02b351;
    color: #fff;
}

.btn-kakao {
    background-color: #fee500;
    border-color: #fee500;
    color: #000;
}

.btn-kakao:hover {
    background-color: #fdd835;
    border-color: #fdd835;
    color: #000;
}

.btn-google {
    background-color: #fff;
    border: 1.5px solid var(--gray-300);
    color: var(--gray-700);
}

.btn-google:hover {
    background-color: var(--gray-50);
    border-color: var(--gray-400);
    color: var(--gray-800);
}

/* ===========================
   오답 노트
   =========================== */
.wrong-note-card {
    transition: opacity var(--transition);
}

/* ===========================
   반응형
   =========================== */
@media (max-width: 991.98px) {
    .navbar-collapse {
        background-color: white;
        padding: 1rem;
        border-radius: var(--radius);
        box-shadow: var(--shadow-lg);
        margin-top: 0.5rem;
    }

    .navbar-nav .dropdown-menu {
        border: none !important;
        box-shadow: none !important;
        padding-left: 1rem !important;
    }

    .hero-section {
        margin: -1rem -12px 0;
        border-radius: 0;
    }

    .hero-section h1 {
        font-size: 1.8rem;
    }
}

@media (max-width: 767.98px) {
    .card-body { padding: 1rem; }

    .btn-lg {
        padding: 0.6rem 1.2rem;
        font-size: 0.95rem;
    }

    .hero-section {
        padding: 2rem 0;
    }

    .hero-section h1 { font-size: 1.5rem; }
    .hero-section .lead { font-size: 1rem; }

    .hero-section .d-flex.gap-3 {
        flex-direction: column;
    }

    .navbar .d-flex {
        flex-direction: column;
        align-items: stretch;
        width: 100%;
    }

    .navbar .d-flex form {
        min-width: auto;
        max-width: none;
        margin-bottom: 10px;
    }

    .navbar .d-flex .form-control { min-width: auto; }

    .dropdown-menu {
        position: static !important;
        float: none;
        width: auto;
        margin-top: 0;
        background-color: transparent !important;
        border: 0 !important;
        border-radius: 0;
        box-shadow: none !important;
    }

    /* 모바일 검색 폼 */
    .search-card .row { gap: 0.5rem; }
}

/* ===========================
   애니메이션
   =========================== */
.fade-in {
    animation: fadeIn 0.4s ease-out;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ===========================
   커스텀 스크롤바
   =========================== */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--gray-100); }
::-webkit-scrollbar-thumb {
    background: var(--gray-300);
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover { background: var(--gray-400); }

/* ===========================
   유틸리티
   =========================== */
.cursor-pointer { cursor: pointer; }
.text-gradient {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* ===========================
   네비바 검색 폼 레이아웃
   =========================== */
.navbar .d-flex {
    align-items: center;
    flex-wrap: nowrap;
}

.navbar .d-flex form {
    min-width: 200px;
    max-width: 300px;
}

.navbar .d-flex .btn {
    white-space: nowrap;
}