:root {
    --bg: #f5f7fa;
    --surface: #ffffff;
    --surface-soft: #f8fafc;

    --text: #172033;
    --muted: #667085;

    --border: #dfe5ec;
    --border-strong: #cbd5e1;

    --primary: #22577a;
    --primary-dark: #17415d;
    --primary-soft: #edf5fa;

    --warning-soft: #fff9e8;
    --warning-border: #ead89e;

    --gpt-soft: #f2f7f5;
    --gpt-border: #bed7cb;

    --danger: #b42318;
    --danger-soft: #fff2f0;

    --success: #166534;
    --success-soft: #f0fdf4;

    --radius: 12px;
    --shadow: 0 1px 3px rgba(16, 24, 40, 0.08);
}

* {
    box-sizing: border-box;
}

html {
    min-height: 100%;
    background: var(--bg);
}

body {
    margin: 0;
    min-height: 100vh;

    color: var(--text);
    background: var(--bg);

    font-family:
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        "PingFang SC",
        "Hiragino Sans GB",
        "Microsoft YaHei",
        Arial,
        sans-serif;

    line-height: 1.65;
}

button,
input,
textarea,
select {
    font: inherit;
}

button {
    cursor: pointer;
}

.hidden {
    display: none !important;
}

.site-shell {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.site-header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
}

.site-header-inner {
    width: min(100% - 32px, 980px);
    min-height: 72px;

    margin: 0 auto;

    display: flex;
    align-items: center;
    justify-content: space-between;

    gap: 20px;
}

.site-kicker {
    color: var(--primary);
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 0.12em;
}

.site-title {
    margin-top: 1px;

    color: var(--text);
    font-size: 19px;
    font-weight: 700;
}

.participant-badge {
    padding: 6px 10px;

    border: 1px solid var(--border);
    border-radius: 999px;

    color: var(--muted);
    background: var(--surface-soft);

    font-size: 12px;
    white-space: nowrap;
}

.app-container {
    width: min(100% - 32px, 860px);
    margin: 32px auto 56px;
    flex: 1;
}

.site-footer {
    padding: 22px 16px;

    border-top: 1px solid var(--border);

    color: var(--muted);
    background: var(--surface);

    text-align: center;
    font-size: 12px;
}

.loading-card,
.page-card,
.case-block,
.form-card {
    border: 1px solid var(--border);
    border-radius: var(--radius);

    background: var(--surface);
    box-shadow: var(--shadow);
}

.loading-card {
    padding: 32px;
    color: var(--muted);
    text-align: center;
}

.page-card {
    padding: 30px;
}

.page-header {
    margin-bottom: 24px;
}

.page-title {
    margin: 0;

    font-size: 25px;
    line-height: 1.35;
}

.page-subtitle {
    margin: 9px 0 0;

    color: var(--muted);
    font-size: 14px;
}

.section-title {
    margin: 30px 0 13px;

    font-size: 20px;
    line-height: 1.4;
}

.progress-wrap {
    margin: 0 0 24px;
}

.progress-meta {
    margin-bottom: 7px;

    display: flex;
    justify-content: space-between;
    gap: 12px;

    color: var(--muted);
    font-size: 13px;
}

.progress-track {
    height: 7px;

    overflow: hidden;

    border-radius: 999px;
    background: #e8edf2;
}

.progress-value {
    height: 100%;

    border-radius: 999px;
    background: var(--primary);

    transition: width 0.2s ease;
}

.notice {
    margin-bottom: 18px;
    padding: 12px 14px;

    border-radius: 8px;

    font-size: 14px;
}

.notice-error {
    border: 1px solid #f2b8b5;

    color: var(--danger);
    background: var(--danger-soft);
}

.notice-success {
    border: 1px solid #bbdfc3;

    color: var(--success);
    background: var(--success-soft);
}

.info-box {
    margin: 18px 0;
    padding: 14px 16px;

    border: 1px solid var(--border);
    border-radius: 9px;

    color: var(--muted);
    background: var(--surface-soft);

    font-size: 14px;
}

.form-grid {
    display: grid;
    gap: 18px;
}

.field-group {
    display: grid;
    gap: 7px;
}

.field-label {
    font-weight: 600;
    font-size: 14px;
}

.field-help {
    color: var(--muted);
    font-size: 12px;
}

.text-input,
.text-area,
.select-input,
.number-input {
    width: 100%;

    border: 1px solid var(--border-strong);
    border-radius: 8px;

    color: var(--text);
    background: var(--surface);

    outline: none;

    transition:
        border-color 0.15s ease,
        box-shadow 0.15s ease;
}

.text-input,
.select-input,
.number-input {
    min-height: 44px;
    padding: 9px 11px;
}

.text-area {
    min-height: 125px;
    padding: 10px 11px;

    resize: vertical;
}

.text-input:focus,
.text-area:focus,
.select-input:focus,
.number-input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(34, 87, 122, 0.12);
}

.button-row {
    margin-top: 24px;

    display: flex;
    justify-content: flex-end;
    gap: 10px;
}

.primary-button,
.secondary-button {
    min-height: 44px;

    padding: 9px 20px;

    border-radius: 8px;

    font-weight: 600;
}

.primary-button {
    border: 1px solid var(--primary);

    color: #ffffff;
    background: var(--primary);
}

.primary-button:hover:not(:disabled) {
    background: var(--primary-dark);
}

.secondary-button {
    border: 1px solid var(--border-strong);

    color: var(--text);
    background: var(--surface);
}

button:disabled {
    cursor: not-allowed;
    opacity: 0.58;
}

.case-blocks {
    display: grid;
    gap: 13px;
}

.case-block {
    padding: 18px 20px;
}

.case-block-title {
    margin: 0 0 8px;

    font-size: 16px;
    font-weight: 700;
}

.case-block-role {
    display: inline-block;

    margin-bottom: 8px;
    padding: 2px 8px;

    border-radius: 999px;

    color: var(--primary-dark);
    background: var(--primary-soft);

    font-size: 12px;
    font-weight: 600;
}

.case-block-content {
    margin: 0;

    white-space: pre-wrap;
    overflow-wrap: anywhere;

    font-size: 15px;
}

.case-block-options {
    margin-top: 10px;
    padding-top: 9px;

    border-top: 1px dashed var(--border);

    color: var(--muted);
    font-size: 13px;
    white-space: pre-wrap;
}

.block-section-header {
    padding: 12px 0 3px;

    border: 0;
    box-shadow: none;
    background: transparent;
}

.block-section-header .case-block-title {
    margin: 0;

    font-size: 21px;
}

.block-time_control {
    border-color: var(--warning-border);
    background: var(--warning-soft);
}

.block-case_material {
    background: #fbfcfe;
}

.block-mdt_opinion {
    border-left: 4px solid #7b9eb5;
}

.block-gpt_mdt_opinion {
    border-color: var(--gpt-border);
    border-left: 4px solid #789e8d;

    background: var(--gpt-soft);
}

.block-task_question,
.block-response_field {
    border-left: 4px solid var(--primary);
    background: var(--primary-soft);
}

.form-card {
    margin-top: 26px;
    padding: 24px;
}

.form-card-title {
    margin: 0 0 6px;

    font-size: 20px;
}

.form-card-subtitle {
    margin: 0 0 22px;

    color: var(--muted);
    font-size: 13px;
}

.divider {
    height: 1px;
    margin: 22px 0;

    background: var(--border);
}

.complete-mark {
    width: 58px;
    height: 58px;

    margin-bottom: 20px;

    display: flex;
    align-items: center;
    justify-content: center;

    border-radius: 50%;

    color: var(--success);
    background: var(--success-soft);

    font-size: 28px;
    font-weight: 700;
}

.feedback-blocks {
    display: grid;
    gap: 14px;
}

.feedback-block {
    padding: 18px 20px;

    border: 1px solid var(--border);
    border-radius: 10px;

    background: var(--surface);
}

.feedback-heading {
    margin: 0 0 7px;

    font-size: 18px;
}

.feedback-content {
    margin: 0;

    white-space: pre-wrap;
}

.fatal-card {
    padding: 28px;

    border: 1px solid #f2b8b5;
    border-radius: var(--radius);

    background: var(--danger-soft);
}

.fatal-card h1 {
    margin-top: 0;
}

@media (max-width: 640px) {
    .site-header-inner {
        width: min(100% - 24px, 980px);
        min-height: 64px;
    }

    .site-title {
        font-size: 17px;
    }

    .participant-badge {
        max-width: 44vw;
        overflow: hidden;
        text-overflow: ellipsis;
    }

    .app-container {
        width: min(100% - 20px, 860px);
        margin-top: 18px;
        margin-bottom: 36px;
    }

    .page-card {
        padding: 21px 17px;
    }

    .page-title {
        font-size: 22px;
    }

    .case-block {
        padding: 15px;
    }

    .form-card {
        padding: 19px 15px;
    }

    .button-row {
        flex-direction: column;
    }

    .primary-button,
    .secondary-button {
        width: 100%;
    }
}


/* ============================================================
   Student UX v2
   ============================================================ */

.app-container:has(.case-layout) {
    width: min(100% - 32px, 1200px);
}

.app-container.case-wide {
    width: min(100% - 32px, 1200px);
}

.case-layout {
    display: grid;
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    gap: 22px;
    align-items: start;
}

.case-left,
.case-right {
    min-width: 0;
}

.case-right .form-card {
    margin-top: 0;
}

.option-group {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.option-pill {
    display: inline-flex;
    align-items: center;
    gap: 8px;

    padding: 10px 14px;

    border: 1px solid var(--border-strong);
    border-radius: 10px;

    background: var(--surface);
    cursor: pointer;

    font-size: 14px;

    transition:
        border-color 0.15s ease,
        background 0.15s ease;
}

.option-pill:hover {
    border-color: var(--primary);
}

.option-pill.selected {
    border-color: var(--primary);
    background: var(--primary-soft);
}

.option-pill input {
    accent-color: var(--primary);
    margin: 0;
}

.slider-field {
    display: grid;
    gap: 8px;
}

.slider-row {
    display: flex;
    align-items: center;
    gap: 14px;
}

.slider-row input[type="range"] {
    flex: 1;
    accent-color: var(--primary);
}

.slider-value {
    min-width: 46px;

    padding: 4px 8px;

    border: 1px solid var(--border);
    border-radius: 8px;

    text-align: center;
    font-weight: 600;
    font-size: 14px;
}

@media (max-width: 900px) {
    .case-layout {
        grid-template-columns: 1fr;
    }
}


/* ============================================================
   IELTS 风格双栏：左阅读(题目/材料) / 右答题，各自独立滚动（两个轴）
   ============================================================ */
.case-workspace {
    display: grid;
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    gap: 24px;
    align-items: start;
}

.case-reading-pane,
.case-answer-pane {
    min-width: 0;
    max-height: calc(100vh - 180px);
    overflow-y: auto;
    padding-right: 6px;
}

.case-reading-pane {
    background: var(--surface-alt, #f6f8fc);
    border: 1px solid var(--border, #e3e8f0);
    border-radius: 14px;
    padding: 18px;
}

.case-answer-pane .form-card {
    margin-top: 0;
}

.reading-groups {
    display: grid;
    gap: 16px;
}

.material-group {
    background: #ffffff;
    border: 1px solid var(--border, #e3e8f0);
    border-radius: 12px;
    padding: 16px;
}

.material-group-time {
    background: #fff7ed;
    border-color: #fed7aa;
}

.material-group-title {
    margin: 0 0 10px;
    font-size: 15px;
    font-weight: 700;
    color: var(--primary, #2b5cff);
}

.reading-section-header {
    margin: 4px 0 8px;
    font-size: 17px;
    font-weight: 700;
}

.material-block-content {
    margin: 6px 0;
    line-height: 1.7;
}

@media (max-width: 1100px) {
    .case-workspace {
        grid-template-columns: 1fr;
    }
    .case-reading-pane,
    .case-answer-pane {
        max-height: none;
        overflow: visible;
    }
}


/* ============================================================
   合并版式：材料组连排 + 校准反馈聊天气泡
   ============================================================ */
.material-group-merged .material-block-content {
    margin: 0 0 12px;
    font-size: 14px;
    line-height: 1.85;
    color: #1f2937;
}

.material-group-merged .material-block-content:last-child {
    margin-bottom: 0;
}

.material-sub-label {
    margin: 14px 0 6px;
    font-size: 13px;
    font-weight: 600;
    color: #475569;
}

.material-group-merged .material-sub-label:first-of-type {
    margin-top: 0;
}

.feedback-chat {
    margin-top: 20px;
}

.feedback-chat-bubble {
    background: var(--surface-alt, #f6f8fc);
    border: 1px solid var(--border, #e3e8f0);
    border-radius: 14px;
    border-top-left-radius: 4px;
    padding: 20px 22px;
    max-width: 760px;
}

.feedback-chat-title {
    margin: 0 0 10px;
    font-size: 13px;
    font-weight: 700;
    color: #64748b;
}

.feedback-chat-text {
    margin: 0 0 14px;
    font-size: 15px;
    line-height: 1.9;
    color: #1f2937;
}

.feedback-chat-text:last-child {
    margin-bottom: 0;
}


.material-group-gpt.material-group-merged {
    border-left: 4px solid var(--primary, #2b5cff);
    background: #f5f8ff;
}

.material-group-gpt .material-sub-label {
    color: var(--primary, #2b5cff);
}