:root {
    --c-bg: #f6f7f9;
    --c-fg: #1f2329;
    --c-muted: #6b7280;
    --c-border: #e4e7eb;
    --c-card: #ffffff;
    --c-primary: #2f6feb;
    --c-primary-dark: #1f54c7;
    --c-warn-bg: #fff7e6;
    --c-warn-border: #f5c542;
    --font-stack: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans KR", Roboto, sans-serif;
    --mono: "JetBrains Mono", "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: var(--font-stack);
    color: var(--c-fg);
    background: var(--c-bg);
    line-height: 1.55;
}

.topbar {
    background: #fff;
    border-bottom: 1px solid var(--c-border);
}

.topbar-inner {
    max-width: 960px;
    margin: 0 auto;
    padding: 0.75rem 1.25rem;
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.brand {
    font-weight: 700;
    color: var(--c-fg);
    text-decoration: none;
}

.topbar nav a {
    margin-right: 1rem;
    color: var(--c-muted);
    text-decoration: none;
    font-weight: 500;
}

.topbar nav a:hover, .topbar nav a.active {
    color: var(--c-primary);
}

.topbar nav {
    flex: 1;
}

/* 언어 전환. 오른쪽 끝으로 밀어 두면 nav 와 사용자 영역 사이에서 흔들리지 않는다. */
.lang-switch {
    margin-left: auto;
    font-size: 0.85rem;
    color: var(--c-muted);
    text-decoration: none;
    white-space: nowrap;
}

.lang-switch:hover {
    color: var(--c-fg);
    text-decoration: underline;
}

.topbar-user {
    color: var(--c-muted);
    font-size: 0.88rem;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.topbar-user span {
    font-family: var(--mono);
    color: var(--c-fg);
}

.btn-link {
    background: none;
    border: none;
    padding: 0;
    color: var(--c-muted);
    cursor: pointer;
    font-size: 0.88rem;
    text-decoration: underline;
}

.btn-link:hover { color: var(--c-primary); }

.login-card {
    max-width: 420px;
    margin: 3rem auto;
}

.login-form {
    display: flex;
    flex-direction: column;
    gap: 0.85rem;
}

.login-form .field {
    display: flex;
    flex-direction: column;
    font-size: 0.85rem;
    color: var(--c-muted);
    gap: 0.3rem;
}

.login-form input {
    padding: 0.5rem 0.7rem;
    border: 1px solid var(--c-border);
    border-radius: 6px;
    font-size: 1rem;
    font-family: var(--font-stack);
}

/* 입력칸 + 표시/숨김 버튼. 버튼 폭은 문구 길이(Show/Hide, 표시/숨김)를 따라가고
   좁은 화면에서는 입력칸이 줄어든다 -- min-width: 0 이 없으면 flex 아이템의 기본
   최소 폭 때문에 카드 밖으로 삐져나간다. */
.password-field {
    display: flex;
    align-items: stretch;
    gap: 0.4rem;
}

.password-field input {
    flex: 1;
    min-width: 0;
}

.login-form .password-toggle {
    flex: none;
    padding: 0 0.75rem;
    font-size: 0.85rem;
    color: var(--c-muted);
    white-space: nowrap;
}

.login-form .password-toggle[aria-pressed="true"] {
    border-color: var(--c-primary);
    color: var(--c-primary);
}

.login-form button { margin-top: 0.5rem; }

.container {
    max-width: 960px;
    margin: 2rem auto;
    padding: 0 1.25rem;
}

.container-wide {
    max-width: 1400px;
}

.hero h1 {
    margin-top: 0;
    font-size: 1.8rem;
}

.hero .btn {
    margin-top: 0.5rem;
}

.meta {
    color: var(--c-muted);
    font-size: 0.95rem;
}

.card {
    background: var(--c-card);
    border: 1px solid var(--c-border);
    border-radius: 8px;
    padding: 1.25rem 1.5rem;
    margin: 1.25rem 0;
}

.card.warn {
    background: var(--c-warn-bg);
    border-color: var(--c-warn-border);
}

.btn {
    display: inline-block;
    padding: 0.45rem 1rem;
    border-radius: 6px;
    border: 1px solid var(--c-border);
    background: #fff;
    color: var(--c-fg);
    font-size: 0.95rem;
    cursor: pointer;
    text-decoration: none;
    font-weight: 500;
}

.btn:hover:not(:disabled) {
    border-color: var(--c-primary);
    color: var(--c-primary);
}

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

.btn.primary:hover:not(:disabled) {
    background: var(--c-primary-dark);
    color: #fff;
}

.btn:disabled {
    opacity: 0.55;
    cursor: not-allowed;
}

.btn-row {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-top: 0.75rem;
}

.agent-note {
    color: var(--c-muted);
    font-size: 0.85rem;
    margin-left: 0.5rem;
}

.lab-actions {
    background: #f0f4ff;
    border-color: #cdd9f7;
}

.crumbs {
    margin: 0 0 1rem;
}

.crumbs a {
    color: var(--c-muted);
    text-decoration: none;
}

.crumbs a:hover { color: var(--c-primary); }

.labs-table {
    width: 100%;
    border-collapse: collapse;
    background: var(--c-card);
    border: 1px solid var(--c-border);
    border-radius: 8px;
    overflow: hidden;
}

.labs-table th, .labs-table td {
    text-align: left;
    padding: 0.6rem 1rem;
    border-bottom: 1px solid var(--c-border);
}

.labs-table thead th {
    background: #fafbfc;
    font-weight: 600;
    color: var(--c-muted);
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.labs-table tbody tr:last-child td { border-bottom: none; }

.labs-table a {
    color: var(--c-primary);
    text-decoration: none;
    font-weight: 500;
}

.labs-table a:hover { text-decoration: underline; }

.guide {
    background: var(--c-card);
    border: 1px solid var(--c-border);
    border-radius: 8px;
    padding: 1.75rem 2rem;
}

.guide h1, .guide h2, .guide h3 { margin-top: 1.5em; }
.guide h1:first-child, .guide h2:first-child { margin-top: 0; }

.guide table {
    border-collapse: collapse;
    margin: 1rem 0;
}

.guide th, .guide td {
    border: 1px solid var(--c-border);
    padding: 0.4rem 0.8rem;
}

.guide th { background: #fafbfc; }

.guide code {
    font-family: var(--mono);
    background: #f1f3f5;
    padding: 0.1em 0.35em;
    border-radius: 4px;
    font-size: 0.92em;
}

.guide pre {
    background: #1e2329;
    color: #e6e8eb;
    padding: 1rem;
    border-radius: 6px;
    overflow-x: auto;
    line-height: 1.45;
}

.guide pre code {
    background: transparent;
    color: inherit;
    padding: 0;
}

.guide blockquote {
    border-left: 4px solid var(--c-primary);
    background: #f5f9ff;
    padding: 0.5rem 1rem;
    margin: 1rem 0;
    color: #2f3338;
}

.footer {
    text-align: center;
    color: var(--c-muted);
    padding: 2rem 0;
}

code {
    font-family: var(--mono);
}

.students-table .agent-result {
    font-family: var(--mono);
    font-size: 0.88rem;
}

.result-idle { color: var(--c-muted); }
.result-pending { color: var(--c-primary); }
.result-ok { color: #1e8a4d; }
.result-bad { color: #c0392b; }

.action-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    flex-wrap: wrap;
}

.student-selector {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    font-size: 0.92rem;
}

.student-selector select {
    padding: 0.3rem 0.5rem;
    border: 1px solid var(--c-border);
    border-radius: 5px;
    background: #fff;
    font-family: var(--mono);
    font-size: 0.85rem;
}

.run-state {
    margin-top: 0.75rem;
    padding: 0.55rem 0.75rem;
    background: #fff;
    border: 1px solid var(--c-border);
    border-radius: 6px;
    font-family: var(--mono);
    font-size: 0.86rem;
    line-height: 1.45;
}

.log-viewer {
    margin-top: 0.75rem;
}

.log-viewer summary {
    cursor: pointer;
    color: var(--c-muted);
    font-size: 0.9rem;
    padding: 0.3rem 0;
    user-select: none;
}

.log-viewer summary:hover { color: var(--c-primary); }

.log-viewer pre {
    background: #1e2329;
    color: #e6e8eb;
    padding: 0.85rem 1rem;
    border-radius: 6px;
    max-height: 320px;
    overflow: auto;
    font-family: var(--mono);
    font-size: 0.82rem;
    line-height: 1.4;
    margin: 0.4rem 0;
    white-space: pre-wrap;
    word-break: break-word;
}

.log-controls {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 0.85rem;
    color: var(--c-muted);
}

/* ----- 강사 대시보드 ----- */

.dashboard-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}

.dashboard-header h1 { margin: 0; }

.status-pill {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.85rem;
    background: #fff;
    border: 1px solid var(--c-border);
    border-radius: 999px;
    padding: 0.3rem 0.8rem;
}

.sse-dot {
    width: 0.7rem;
    height: 0.7rem;
    border-radius: 50%;
    background: var(--c-muted);
    transition: background 0.2s;
}
.sse-dot.sse-open { background: #1e8a4d; }
.sse-dot.sse-connecting { background: #d4a017; animation: pulse 1.2s infinite; }
.sse-dot.sse-error { background: #c0392b; }

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.35; }
}

.legend {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    font-size: 0.82rem;
    color: var(--c-muted);
    margin: 1rem 0 0.5rem;
}

.legend-item {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
}

.legend-swatch {
    width: 1.1rem;
    height: 1.1rem;
    border-radius: 3px;
    display: inline-block;
    border: 1px solid var(--c-border);
}

.swatch-idle    { background: #f1f3f5; }
.swatch-running { background: #4a90e2; color: #fff; }
.swatch-success { background: #4caf50; color: #fff; }
.swatch-failed  { background: #c0392b; color: #fff; }
.swatch-killed  { background: #ad7a36; color: #fff; }
.swatch-stale   { background: #2b2f33; color: #aaa; }

.grid-wrap {
    overflow-x: auto;
    background: var(--c-card);
    border: 1px solid var(--c-border);
    border-radius: 8px;
    margin: 0.5rem 0 1.5rem;
}

.instructor-grid {
    border-collapse: separate;
    border-spacing: 0;
    font-family: var(--mono);
    font-size: 0.85rem;
}

.instructor-grid th, .instructor-grid td {
    border-bottom: 1px solid var(--c-border);
    border-right: 1px solid var(--c-border);
    padding: 0;
}

.instructor-grid thead th {
    position: sticky;
    top: 0;
    background: #fafbfc;
    color: var(--c-muted);
    font-weight: 600;
    padding: 0.5rem 0.4rem;
    text-align: center;
    font-size: 0.75rem;
    letter-spacing: 0.04em;
    z-index: 2;
}

.sticky-col {
    position: sticky;
    left: 0;
    background: #fafbfc;
    z-index: 3;
    text-align: left !important;
    padding: 0.4rem 0.8rem !important;
    min-width: 14rem;
    border-right: 2px solid var(--c-border);
}

.instructor-grid thead .sticky-col { z-index: 4; }

.student-cell {
    display: flex;
    flex-direction: column;
    line-height: 1.3;
    gap: 0.1rem;
}

.student-cell strong { font-size: 0.95rem; }
.student-cell small {
    color: var(--c-muted);
    font-family: var(--font-stack);
    font-size: 0.78rem;
}

.student-cell .hb-info.stale {
    color: var(--c-warn-border);
}

.lab-col {
    min-width: 2.4rem;
    max-width: 2.4rem;
}

.lab-cell {
    width: 2.4rem;
    height: 2.4rem;
    text-align: center;
    cursor: pointer;
    font-weight: 600;
    transition: transform 0.08s, filter 0.08s;
}

.lab-cell:hover {
    filter: brightness(1.1);
    transform: scale(1.05);
}

/* ----- 셀 클릭 시 사이드 패널 ----- */

.detail-pane {
    position: fixed;
    right: 0;
    top: 0;
    bottom: 0;
    width: min(420px, 92vw);
    background: #fff;
    border-left: 1px solid var(--c-border);
    box-shadow: -8px 0 24px rgba(0, 0, 0, 0.08);
    padding: 1.25rem 1.5rem;
    transform: translateX(100%);
    transition: transform 0.18s;
    z-index: 10;
    overflow-y: auto;
}

.detail-pane.open {
    transform: translateX(0);
}

.detail-pane h3 {
    margin: 0 0 1rem;
    font-family: var(--mono);
}

.detail-pane h4 {
    margin: 1.2rem 0 0.5rem;
    color: var(--c-muted);
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.close-btn {
    float: right;
    background: none;
    border: none;
    font-size: 1.6rem;
    color: var(--c-muted);
    cursor: pointer;
    line-height: 1;
}

.close-btn:hover { color: var(--c-fg); }

dl.kv {
    display: grid;
    grid-template-columns: max-content 1fr;
    gap: 0.3rem 1rem;
    font-size: 0.85rem;
    margin: 0;
}

dl.kv dt { color: var(--c-muted); }
dl.kv dd { margin: 0; }

/* ---- 단계별 절차 (랩 화면) ---------------------------------------------
   앞 단계가 끝나야 다음이 열린다. 잠긴 단계는 숨기지 않고 흐리게 둔다 —
   전체 절차가 몇 단계인지 처음부터 보이는 편이 학생에게 낫다. */
ol.lab-steps {
    list-style: none;
    counter-reset: none;
    margin: 0.5rem 0 0.75rem;
    padding: 0;
    display: grid;
    gap: 0.5rem;
}

.lab-step {
    border: 1px solid var(--c-border);
    border-left: 3px solid var(--c-border);
    border-radius: 6px;
    padding: 0.6rem 0.75rem;
    background: var(--c-card);
}

.lab-step-head {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.lab-step-no {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1.5rem;
    height: 1.5rem;
    border-radius: 50%;
    background: var(--c-bg);
    border: 1px solid var(--c-border);
    font-size: 0.8rem;
    color: var(--c-muted);
    flex: none;
}

.lab-step-detail {
    margin: 0.3rem 0 0.5rem 2rem;
}

.lab-step-guide {
    margin: -0.2rem 0 0.5rem 2rem;
    font-size: 0.85rem;
}

.lab-step-do {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-left: 2rem;
}

.lab-step-manual {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    font-size: 0.85rem;
    color: var(--c-muted);
}

.lab-step-status {
    font-size: 0.8rem;
    color: #1a7f37;
}

.lab-step.step-done {
    border-left-color: #1a7f37;
}

.lab-step.step-done .lab-step-no {
    background: #1a7f37;
    border-color: #1a7f37;
    color: #fff;
}

/* 잠긴 단계 — 읽을 수는 있고 누를 수는 없다. */
.lab-step.step-locked {
    opacity: 0.55;
}

/* 내 VM 카드 — 라벨/주소 두 칸. 주소가 길어도 카드를 밀지 않게 줄바꿈을 허용한다. */
.myvm {
    border-collapse: collapse;
    margin: 0 0 0.6rem;
}

.myvm th {
    text-align: left;
    font-weight: 600;
    padding: 0.25rem 1rem 0.25rem 0;
    white-space: nowrap;
    vertical-align: top;
}

.myvm td {
    padding: 0.25rem 0;
    word-break: break-all;
}

/* 내 VM 준비 상태 */
.vm-status {
    margin: 0 0 0.6rem;
    font-size: 0.9rem;
}

/* 준비 전 링크 — 막지는 않는다. agent 만 죽고 콘솔은 멀쩡한 경우가 있어서,
   막으면 들어갈 수 있는 학생을 못 들어가게 한다. 흐리게 해서 알리기만 한다. */
.myvm a.vm-link-pending {
    opacity: 0.55;
    text-decoration-style: dashed;
}

/* 관문 두 개 — 학생이 겪는 순서대로 */
.myvm-gates {
    margin: 0 0 0.4rem;
    font-size: 0.9rem;
}

.myvm-gates dt {
    font-weight: 600;
    margin-top: 0.35rem;
}

.myvm-gates dd {
    margin: 0.1rem 0 0 1rem;
    color: var(--c-muted);
}