/* ===== Theme Variables ===== */
:root {
    --bg-gradient: linear-gradient(135deg, #0f0c29, #302b63, #24243e);
    --bg-1: #0f0c29; --bg-2: #302b63; --bg-3: #24243e;
    --bg-card: rgba(255,255,255,0.06);
    --bg-item: rgba(255,255,255,0.04);
    --bg-hover: rgba(255,255,255,0.05);
    --bg-input: rgba(255,255,255,0.08);
    --bg-modal: #1e1e3a;
    --bg-select: #1a1a2e;
    --bg-inset: rgba(0,0,0,0.2);
    --bg-toast: rgba(0,0,0,0.8);
    --text: #e0e0e0;
    --text-2: #ccd6e0;
    --text-3: #a0b0c8;
    --text-4: #7a8aa0;
    --text-muted: #555;
    --text-bright: #fff;
    --border: rgba(255,255,255,0.3);
    --border-light: rgba(255,255,255,0.15);
    --border-subtle: rgba(255,255,255,0.1);
    --accent: #00d2ff;
    --accent-2: #3a7bd5;
    --accent-a30: rgba(0,210,255,0.3);
    --accent-a20: rgba(0,210,255,0.2);
    --accent-a15: rgba(0,210,255,0.15);
    --accent-a12: rgba(0,210,255,0.12);
    --accent-a10: rgba(0,210,255,0.1);
    --accent-a03: rgba(0,210,255,0.03);
    --gradient-primary: linear-gradient(90deg, #00d2ff, #3a7bd5);
    --success: #00cec9;
    --success-2: #00b894;
    --success-a20: rgba(0,206,201,0.2);
    --success-a15: rgba(0,206,201,0.15);
    --success-a10: rgba(0,206,201,0.1);
    --danger: #d63031;
    --danger-2: #e17055;
    --danger-a30: rgba(214,48,49,0.3);
    --danger-a20: rgba(214,48,49,0.2);
    --danger-a15: rgba(214,48,49,0.15);
    --danger-a10: rgba(214,48,49,0.1);
    --warn: #feca57;
    --warn-2: #fdcb6e;
    --warn-3: #f39c12;
    --warn-a20: rgba(254,202,87,0.2);
    --warn-a15: rgba(254,202,87,0.15);
    --warn-a08: rgba(254,202,87,0.08);
    --info: #74b9ff;
    --info-a25: rgba(116,185,255,0.25);
    --info-a15: rgba(116,185,255,0.15);
    --info-a10: rgba(116,185,255,0.1);
    --color-overlay: rgba(0,0,0,0.6);
}
[data-theme="light"] {
    --bg-gradient: linear-gradient(135deg, #f0f2f5, #e8ecf1, #f5f7fa);
    --bg-1: #f0f2f5; --bg-2: #e8ecf1; --bg-3: #f5f7fa;
    --bg-card: rgba(255,255,255,0.85);
    --bg-item: rgba(0,0,0,0.02);
    --bg-hover: rgba(0,0,0,0.03);
    --bg-input: rgba(0,0,0,0.04);
    --bg-modal: #ffffff;
    --bg-select: #ffffff;
    --bg-inset: rgba(0,0,0,0.04);
    --bg-toast: rgba(0,0,0,0.75);
    --text: #333333;
    --text-2: #444444;
    --text-3: #666666;
    --text-4: #888888;
    --text-muted: #aaaaaa;
    --text-bright: #1a1a1a;
    --border: rgba(0,0,0,0.15);
    --border-light: rgba(0,0,0,0.12);
    --border-subtle: rgba(0,0,0,0.08);
    --accent: #0984e3;
    --accent-2: #0652ab;
    --accent-a30: rgba(9,132,227,0.3);
    --accent-a20: rgba(9,132,227,0.2);
    --accent-a15: rgba(9,132,227,0.15);
    --accent-a12: rgba(9,132,227,0.12);
    --accent-a10: rgba(9,132,227,0.1);
    --accent-a03: rgba(9,132,227,0.03);
    --gradient-primary: linear-gradient(90deg, #0984e3, #0652ab);
    --success: #00a88a;
    --success-2: #00896e;
    --success-a20: rgba(0,168,138,0.2);
    --success-a15: rgba(0,168,138,0.15);
    --success-a10: rgba(0,168,138,0.1);
    --danger: #d63031;
    --danger-2: #e17055;
    --danger-a30: rgba(214,48,49,0.3);
    --danger-a20: rgba(214,48,49,0.15);
    --danger-a15: rgba(214,48,49,0.12);
    --danger-a10: rgba(214,48,49,0.08);
    --warn: #e67e22;
    --warn-2: #f39c12;
    --warn-3: #d68910;
    --warn-a20: rgba(230,126,34,0.2);
    --warn-a15: rgba(230,126,34,0.15);
    --warn-a08: rgba(230,126,34,0.08);
    --info: #2980b9;
    --info-a25: rgba(41,128,185,0.25);
    --info-a15: rgba(41,128,185,0.15);
    --info-a10: rgba(41,128,185,0.1);
    --color-overlay: rgba(0,0,0,0.35);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    background: var(--bg-gradient);
    color: var(--text); min-height: 100vh;
}
.container { max-width: 1100px; margin: 0 auto; padding: 20px; }

/* Login */
.login-wrap { display: flex; justify-content: center; align-items: center; min-height: 100vh; }
.login-box {
    background: var(--bg-card); backdrop-filter: blur(20px);
    border: 1px solid var(--border-light); border-radius: 20px;
    padding: 40px; width: 380px; text-align: center;
}
.login-box h1 {
    font-size: 28px; background: var(--gradient-primary);
    -webkit-background-clip: text; -webkit-text-fill-color: transparent; margin-bottom: 8px;
}
.login-box .subtitle { color: var(--text-4); font-size: 14px; margin-bottom: 30px; }
.login-box input {
    width: 100%; padding: 14px 16px; margin-bottom: 14px;
    background: var(--bg-input); border: 1px solid var(--border-light);
    border-radius: 12px; color: var(--text-bright); font-size: 15px; outline: none;
}
.login-box input:focus { border-color: var(--accent); }
.login-box input::placeholder { color: var(--text-muted); }
.login-btn {
    width: 100%; padding: 14px; border: none; border-radius: 12px;
    background: var(--gradient-primary);
    color: var(--text-bright); font-size: 16px; font-weight: bold; cursor: pointer; transition: all .3s;
}
.login-btn:hover { transform: translateY(-2px); box-shadow: 0 8px 25px var(--accent-a30); }
.login-error { color: var(--danger); font-size: 13px; margin-top: 10px; display: none; }

/* Header */
.header {
    display: flex; justify-content: space-between; align-items: center;
    padding: 16px 0; border-bottom: 1px solid var(--border-subtle); margin-bottom: 24px;
}
.header h2 {
    font-size: 20px; background: var(--gradient-primary);
    -webkit-background-clip: text; -webkit-text-fill-color: transparent;
}
.header .user-info { display: flex; align-items: center; gap: 10px; }
.header .user-name { color: var(--text-3); font-size: 14px; }
.header-btn {
    padding: 6px 14px; border-radius: 8px; cursor: pointer; font-size: 13px; border: none;
}
.pwd-btn { background: var(--info-a15); border: 1px solid var(--info-a25); color: var(--info); }
.pwd-btn:hover { background: var(--info-a25); }
.logout-btn { background: var(--danger-a20); border: 1px solid var(--danger-a30); color: var(--danger); }
.logout-btn:hover { background: var(--danger-a30); }
.theme-toggle {
    width: 36px; height: 36px; border-radius: 10px; border: 1px solid var(--border-light);
    background: var(--bg-card); cursor: pointer; font-size: 18px; display: flex;
    align-items: center; justify-content: center; transition: all .3s; padding: 0;
}
.theme-toggle:hover { background: var(--bg-input); transform: rotate(20deg); }

/* Tabs */
.tabs { display: flex; gap: 8px; margin-bottom: 24px; flex-wrap: wrap; }
.tab-btn {
    padding: 10px 20px; background: var(--bg-card);
    border: 1px solid var(--border-subtle); border-radius: 10px;
    color: var(--text-3); cursor: pointer; font-size: 14px; transition: all .3s;
}
.tab-btn.active { background: var(--accent-a15); border-color: var(--accent-a30); color: var(--accent); }
.tab-btn:hover { background: var(--border-subtle); }

/* Cards */
.card {
    background: var(--bg-card); backdrop-filter: blur(10px);
    border: 1px solid var(--border-subtle); border-radius: 16px;
    padding: 24px; margin-bottom: 16px;
}
.card h3 { color: var(--accent); margin-bottom: 16px; font-size: 17px; }

/* Form */
.form-input, .form-select, .form-textarea {
    width: 100%; padding: 12px 14px; margin-bottom: 12px;
    background: var(--bg-input); border: 1px solid var(--border-light);
    border-radius: 10px; color: var(--text-bright); font-size: 14px; outline: none;
}
.form-input:focus, .form-select:focus, .form-textarea:focus { border-color: var(--accent); }
.form-input::placeholder, .form-textarea::placeholder { color: var(--text-muted); }
.form-textarea { min-height: 80px; resize: vertical; font-family: inherit; }
.form-select { cursor: pointer; }
.form-select option { background: var(--bg-select); color: var(--text-bright); }
.form-label { display: block; color: var(--text-3); font-size: 13px; margin-bottom: 6px; }
.form-row { display: flex; gap: 12px; }
.form-row > * { flex: 1; }

/* Buttons */
.btn {
    padding: 10px 20px; border: none; border-radius: 10px;
    font-size: 14px; font-weight: bold; cursor: pointer; transition: all .3s;
}
.btn-primary { background: var(--gradient-primary); color: var(--text-bright); }
.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 4px 15px var(--accent-a30); }
.btn-success { background: linear-gradient(90deg, var(--success), var(--success)); color: var(--text-bright); }
.btn-danger { background: linear-gradient(90deg, var(--danger-2), var(--danger)); color: var(--text-bright); }
.btn-warn { background: linear-gradient(90deg, var(--warn-2), var(--warn-3)); color: var(--text); }
.btn-sm { padding: 6px 14px; font-size: 12px; border-radius: 8px; }
.btn-group { display: flex; gap: 8px; flex-wrap: wrap; }

/* Table */
.data-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.data-table th {
    background: var(--accent-a10); color: var(--accent); padding: 12px 14px;
    text-align: left; font-weight: bold; border-bottom: 2px solid var(--accent-a20);
}
.data-table td { padding: 10px 14px; border-bottom: 1px solid var(--bg-card); color: var(--text-2); }
.data-table tr:hover td { background: var(--accent-a03); }

/* Exam/Student items */
.exam-item {
    background: var(--bg-item); border: 1px solid var(--bg-input);
    border-radius: 12px; padding: 18px; margin-bottom: 12px;
    display: flex; justify-content: space-between; align-items: center;
}
.exam-item .exam-info { flex: 1; }
.exam-item .exam-title { font-size: 16px; font-weight: bold; color: var(--text-bright); margin-bottom: 4px; }
.exam-item .exam-desc { font-size: 13px; color: var(--text-4); margin-bottom: 6px; }
.exam-item .exam-meta { font-size: 12px; color: var(--text-muted); }
.exam-item .exam-actions { display: flex; gap: 8px; flex-wrap: wrap; }

/* Class badge */
.class-badge {
    display: inline-block; padding: 2px 10px; border-radius: 12px;
    background: var(--info-a15); color: var(--info); font-size: 12px; margin-right: 6px;
}

/* Question panel */
.question-panel { display: none; }
.question-panel.active { display: block; }
.q-item {
    background: var(--bg-item); border: 1px solid var(--bg-input);
    border-radius: 10px; padding: 14px; margin-bottom: 10px;
}
.q-item .q-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 8px; }
.q-type { font-size: 11px; padding: 2px 8px; border-radius: 6px; }
.q-type-choice { background: var(--accent-a15); color: var(--accent); }
.q-type-fill { background: var(--warn-a15); color: var(--warn); }
.q-type-tf { background: var(--success-a15); color: var(--success); }
.q-item .q-content { font-size: 14px; color: var(--text-2); margin-bottom: 6px; }
.q-item .q-answer { font-size: 12px; color: var(--success); }
.q-item .q-score { font-size: 12px; color: var(--text-4); }

/* Take exam */
.take-q {
    background: var(--bg-card); border: 1px solid var(--border-subtle);
    border-radius: 14px; padding: 20px; margin-bottom: 16px;
}
.take-q .q-num { color: var(--accent); font-size: 13px; font-weight: bold; margin-bottom: 8px; }
.take-q .q-text { font-size: 15px; color: var(--text-bright); margin-bottom: 14px; line-height: 1.6; }
.take-q .q-pts { color: var(--text-4); font-size: 12px; margin-bottom: 10px; }
.option-item {
    display: flex; align-items: center; gap: 10px; padding: 10px 14px;
    background: var(--bg-item); border: 1px solid var(--bg-input);
    border-radius: 10px; margin-bottom: 8px; cursor: pointer; transition: all .2s;
}
.option-item:hover { background: var(--bg-input); }
.option-item.selected { background: var(--accent-a12); border-color: var(--accent-a30); }
.option-item .opt-label { font-weight: bold; color: var(--accent); min-width: 24px; }

/* Result */
.result-correct { border-left: 3px solid var(--success); }
.result-wrong { border-left: 3px solid var(--danger); }
.rd-answer { margin-top: 8px; font-size: 13px; }
.rd-correct { color: var(--success); }
.rd-wrong { color: var(--danger); }
.rd-your { color: var(--text-4); }
.review-box {
    background: var(--warn-a08); border: 1px solid var(--warn-a20);
    border-radius: 12px; padding: 16px; margin-top: 16px;
}
.review-box h4 { color: var(--warn); margin-bottom: 8px; }
.review-box p { color: var(--text-2); font-size: 14px; line-height: 1.6; }

/* Stats */
.stat-bar { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.stat-bar .sb-label { min-width: 40px; font-size: 13px; color: var(--text-3); text-align: right; }
.stat-bar .sb-track { flex: 1; height: 8px; background: var(--bg-input); border-radius: 4px; overflow: hidden; }
.stat-bar .sb-fill { height: 100%; border-radius: 4px; transition: width .5s; }
.stat-bar .sb-value { min-width: 50px; font-size: 13px; color: var(--text-4); }

/* Modal */
.modal-overlay {
    display: none; position: fixed; top: 0; left: 0; right: 0; bottom: 0;
    background: var(--color-overlay); z-index: 1000; justify-content: center; align-items: center;
}
.modal-overlay.active { display: flex; }
.modal-box {
    background: var(--bg-modal); border: 1px solid var(--border-light);
    border-radius: 16px; padding: 28px; width: 480px; max-width: 90vw;
    max-height: 80vh; overflow-y: auto;
}
.modal-box h3 { color: var(--accent); margin-bottom: 16px; font-size: 18px; }
.modal-close {
    float: right; background: none; border: none; color: var(--text-4);
    font-size: 20px; cursor: pointer; line-height: 1;
}
.modal-close:hover { color: var(--text-bright); }

/* Filter bar */
.filter-bar {
    display: flex; gap: 12px; align-items: center; margin-bottom: 16px; flex-wrap: wrap;
}
.filter-bar .form-select { width: auto; min-width: 160px; margin-bottom: 0; }

/* Toast */
.toast {
    position: fixed; bottom: 40px; left: 50%; transform: translateX(-50%);
    background: var(--bg-toast); color: var(--text-bright); padding: 12px 28px;
    border-radius: 20px; font-size: 14px; z-index: 9999;
    opacity: 0; transition: opacity .3s; pointer-events: none;
}
.toast.show { opacity: 1; }

/* Batch result */
.batch-result { margin-top: 12px; padding: 12px; border-radius: 10px; font-size: 13px; }
.batch-result.ok { background: var(--success-a10); border: 1px solid var(--success-a20); }
.batch-result.err { background: var(--danger-a10); border: 1px solid var(--danger-a20); }

/* Responsive */
@media (max-width: 768px) {
    .container { padding: 12px; }
    .login-box { width: 90%; padding: 30px 20px; }
    .exam-item { flex-direction: column; align-items: flex-start; gap: 12px; }
    .form-row { flex-direction: column; }
    .header { flex-direction: column; gap: 10px; text-align: center; }
    .modal-box { width: 95vw; padding: 20px; }
}

/* Question Edit Modal */
.q-edit-modal .modal-box { width: 600px; }
.q-edit-modal .modal-box .form-textarea { min-height: 80px; }
.q-edit-modal .modal-box .opt-hint { font-size: 12px; color: var(--text-4); margin-top: -8px; margin-bottom: 10px; }

/* Edit Exam Modal */
.exam-edit-modal .modal-box { width: 520px; }

/* Wrong answer options styling */
.q-options { margin: 8px 0; }
.wa-opt { display: flex; align-items: center; padding: 6px 10px; border-radius: 6px; margin: 3px 0; font-size: 14px; color: var(--text-3); background: rgba(255,255,255,0.03); }
.wa-opt .opt-label { display: inline-flex; align-items: center; justify-content: center; width: 22px; height: 22px; border-radius: 50%; background: rgba(255,255,255,0.08); font-size: 12px; font-weight: 600; margin-right: 8px; flex-shrink: 0; }
.wa-opt.wa-correct { background: rgba(0,206,201,0.12); color: var(--success); }
.wa-opt.wa-correct .opt-label { background: var(--success); color: #fff; }
.wa-opt.wa-wrong { background: rgba(214,48,49,0.10); color: var(--danger); }
.wa-opt.wa-wrong .opt-label { background: var(--danger); color: #fff; }