:root {
    color-scheme: light;
    --bg: #eef2f6;
    --panel: #ffffff;
    --panel-soft: #f7f9fc;
    --line: #d9e3ee;
    --line-strong: #b9c7d6;
    --text: #102235;
    --muted: #65768a;
    --primary: #1769aa;
    --primary-dark: #0f548b;
    --success: #157f55;
    --danger: #b9362d;
    --warning: #946812;
    --shadow: 0 16px 40px rgba(16, 34, 53, 0.1);
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    background: var(--bg);
    color: var(--text);
    font-family: Inter, "Segoe UI", Roboto, Arial, sans-serif;
    letter-spacing: 0;
}

button,
input,
select {
    font: inherit;
}

button {
    cursor: pointer;
}

.topbar {
    min-height: 68px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 14px;
    padding: 12px 18px;
    background: #102235;
    color: #fff;
}

.topbar h1,
.panel h2,
.modal h2 {
    margin: 0;
}

.topbar h1 {
    font-size: 20px;
}

.topbar p,
.panel p,
.modal p {
    margin: 3px 0 0;
    color: var(--muted);
    font-size: 13px;
}

.topbar p {
    color: #b9c8d9;
}

.topbar-actions,
.panel-head,
.filters-grid,
.submission-head,
.submission-meta,
.answer-head,
.answer-footer,
.form-actions {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.topbar-actions,
.panel-head,
.submission-head,
.answer-head {
    justify-content: space-between;
}

.btn {
    min-height: 36px;
    border: 1px solid var(--line);
    border-radius: 7px;
    background: #fff;
    color: var(--text);
    padding: 0 13px;
    font-size: 13px;
    font-weight: 700;
}

.btn:hover {
    border-color: var(--line-strong);
    background: #f1f5f9;
}

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

.btn.primary:hover {
    background: var(--primary-dark);
}

.wide-btn {
    width: 100%;
}

.app-shell {
    display: grid;
    grid-template-columns: 300px minmax(0, 1fr);
    gap: 14px;
    width: min(1280px, calc(100vw - 24px));
    margin: 14px auto;
}

.panel {
    min-width: 0;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: var(--panel);
    box-shadow: var(--shadow);
    padding: 16px;
}

.login-panel {
    grid-column: 1 / -1;
    width: min(460px, 100%);
    margin: 10vh auto 0;
    display: grid;
    gap: 14px;
}

.classroom-panel {
    align-self: start;
    position: sticky;
    top: 14px;
}

.dashboard {
    display: grid;
    gap: 14px;
    min-width: 0;
}

.field {
    display: grid;
    gap: 6px;
}

.field span {
    color: #41546b;
    font-size: 12px;
    font-weight: 800;
    text-transform: uppercase;
}

.field input,
.field select {
    width: 100%;
    min-height: 38px;
    border: 1px solid var(--line);
    border-radius: 7px;
    background: #fff;
    color: var(--text);
    padding: 8px 10px;
}

.classroom-list,
.submission-list,
.answer-details {
    display: grid;
    gap: 10px;
    margin-top: 12px;
}

.classroom-card,
.submission-card,
.answer-card,
.empty-card {
    border: 1px solid var(--line);
    border-radius: 8px;
    background: var(--panel-soft);
    padding: 12px;
}

.classroom-card {
    width: 100%;
    text-align: left;
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 8px;
    align-items: start;
}

.classroom-card.active {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(23, 105, 170, 0.12);
}

.classroom-card strong,
.submission-card strong {
    font-size: 14px;
}

.classroom-select {
    min-width: 0;
    border: 0;
    background: transparent;
    color: inherit;
    padding: 0;
    text-align: left;
    display: grid;
    gap: 6px;
}

.classroom-edit-btn {
    min-height: 30px;
    padding: 0 10px;
}

.question-list-label {
    color: var(--muted);
    font-size: 12px;
    font-weight: 700;
}

.count-chip,
.status-chip,
.meta-chip {
    display: inline-flex;
    align-items: center;
    min-height: 24px;
    border-radius: 999px;
    background: #edf4fa;
    color: #40566d;
    padding: 0 9px;
    font-size: 12px;
    font-weight: 800;
}

.status-chip.enabled,
.meta-chip.correct {
    color: var(--success);
    background: #eaf8f1;
}

.status-chip.disabled,
.meta-chip.wrong {
    color: var(--danger);
    background: #fff1ef;
}

.meta-chip.manual {
    color: var(--warning);
    background: #fff8e8;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 10px;
}

.stat-card {
    border: 1px solid var(--line);
    border-radius: 8px;
    background: var(--panel-soft);
    padding: 12px;
}

.stat-card span {
    display: block;
    color: var(--muted);
    font-size: 12px;
    font-weight: 800;
    text-transform: uppercase;
}

.stat-card strong {
    display: block;
    margin-top: 5px;
    font-size: 22px;
}

.filters-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    margin-top: 14px;
}

.submission-card {
    display: grid;
    gap: 9px;
}

.submission-meta,
.answer-footer {
    color: var(--muted);
    font-size: 13px;
}

.score-bar {
    height: 8px;
    overflow: hidden;
    border-radius: 999px;
    background: #e3eaf2;
}

.score-fill {
    height: 100%;
    width: 0;
    background: var(--primary);
}

.rich-content {
    line-height: 1.55;
    overflow-wrap: anywhere;
}

.rich-content img {
    max-width: 100%;
    height: auto;
    border-radius: 6px;
}

.rich-content table {
    border-collapse: collapse;
    max-width: 100%;
    margin: 8px 0;
}

.rich-content td,
.rich-content th {
    border: 1px solid var(--line-strong);
    padding: 6px 8px;
}

.modal {
    width: min(1080px, calc(100vw - 24px));
    border: none;
    padding: 0;
    background: transparent;
}

.modal::backdrop {
    background: rgba(7, 18, 31, 0.52);
}

.classroom-modal {
    width: min(620px, calc(100vw - 24px));
}

.modal-card {
    display: grid;
    gap: 14px;
    max-height: calc(100vh - 32px);
    overflow: auto;
    border-radius: 8px;
    background: var(--panel);
    box-shadow: var(--shadow);
    padding: 16px;
}

.classroom-edit-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
}

.toggle-field {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: #41546b;
    font-size: 13px;
    font-weight: 800;
}

.toggle-field input {
    width: 18px;
    height: 18px;
    accent-color: var(--primary);
}

.form-actions {
    justify-content: flex-end;
}

.modal-head {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    align-items: flex-start;
}

.toast {
    position: fixed;
    right: 16px;
    bottom: 16px;
    min-width: 220px;
    max-width: calc(100vw - 32px);
    transform: translateY(20px);
    opacity: 0;
    pointer-events: none;
    border-radius: 8px;
    background: #102235;
    color: #fff;
    padding: 11px 13px;
    box-shadow: var(--shadow);
    transition: opacity 0.18s, transform 0.18s;
    font-size: 13px;
}

.toast.show {
    opacity: 1;
    transform: translateY(0);
}

@media (max-width: 980px) {
    .app-shell {
        grid-template-columns: 1fr;
    }

    .classroom-panel {
        position: static;
    }

    .classroom-list {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .classroom-card {
        grid-template-columns: minmax(0, 1fr);
    }

    .stats-grid,
    .filters-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

@media (max-width: 640px) {
    .topbar,
    .topbar-actions,
    .panel-head,
    .modal-head,
    .submission-head,
    .answer-head {
        align-items: stretch;
        flex-direction: column;
    }

    .topbar-actions .btn,
    .modal-head .btn {
        width: 100%;
    }

    .classroom-list,
    .classroom-edit-grid,
    .stats-grid,
    .filters-grid {
        grid-template-columns: 1fr;
    }

    .form-actions .btn,
    .classroom-edit-btn {
        width: 100%;
    }

    .panel,
    .modal-card {
        padding: 12px;
    }
}