:root {
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-tertiary: #21262d;
    --bg-card: #161b22;
    --border-color: #30363d;
    --text-primary: #f0f6fc;
    --text-secondary: #8b949e;
    --text-muted: #6e7681;
    --accent: #58a6ff;
    --accent-hover: #388bfd;
    --accent-glow: rgba(88, 166, 255, 0.15);
    --success: #238636;
    --success-light: #2ea043;
    --warning: #d29922;
    --danger: #da3633;
    --danger-light: #f85149;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --font-mono: 'Fira Code', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
}

[data-theme="light"] {
    --bg-primary: #f6f8fa;
    --bg-secondary: #ffffff;
    --bg-tertiary: #eaeef2;
    --bg-card: #ffffff;
    --border-color: #d0d7de;
    --text-primary: #1f2328;
    --text-secondary: #57609a;
    --text-muted: #8c959f;
    --accent: #0969da;
    --accent-hover: #0856b3;
    --accent-glow: rgba(9, 105, 218, 0.1);
    --success: #1a7f37;
    --success-light: #2da44e;
    --warning: #9a6700;
    --danger: #cf222e;
    --danger-light: #fa4549;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Navbar */
.navbar {
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    max-width: 1440px;
    margin: 0 auto;
    padding: 0.75rem 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    text-decoration: none;
    color: var(--text-primary);
    font-size: 1.15rem;
}

.brand-logo {
    background: linear-gradient(135deg, #58a6ff, #bc8cff);
    color: #ffffff;
    font-weight: 700;
    font-size: 1.1rem;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-sm);
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 1.25rem;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    padding: 0.4rem 0.6rem;
    border-radius: var(--radius-sm);
    transition: all 0.2s ease;
}

.nav-link:hover, .nav-link.active {
    color: var(--text-primary);
    background-color: var(--bg-tertiary);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.user-pill {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    background-color: var(--bg-tertiary);
    padding: 0.3rem 0.75rem;
    border-radius: 20px;
    font-size: 0.85rem;
    border: 1px solid var(--border-color);
}

.user-role-badge {
    font-size: 0.75rem;
    padding: 0.15rem 0.5rem;
    border-radius: 12px;
    font-weight: 600;
}

.role-teacher, .role-admin {
    background-color: #388bfd26;
    color: #58a6ff;
}

.role-student {
    background-color: #2ea04326;
    color: #3fb950;
}

.btn-logout {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.8rem;
    margin-left: 0.3rem;
}
.btn-logout:hover {
    color: var(--danger-light);
}

/* Layout */
.main-content {
    flex: 1;
    padding: 1.5rem 0;
}

.container {
    max-width: 1440px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.footer {
    background-color: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: 1rem 0;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.4rem;
    font-family: inherit;
    font-size: 0.9rem;
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-sm);
    border: 1px solid transparent;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.15s ease;
}

.btn-primary {
    background-color: var(--accent);
    color: #ffffff;
}
.btn-primary:hover {
    background-color: var(--accent-hover);
}

.btn-success {
    background-color: var(--success);
    color: #ffffff;
}
.btn-success:hover {
    background-color: var(--success-light);
}

.btn-secondary {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    border-color: var(--border-color);
}
.btn-secondary:hover {
    background-color: var(--border-color);
}

.btn-danger {
    background-color: var(--danger);
    color: #ffffff;
}
.btn-danger:hover {
    background-color: var(--danger-light);
}

.btn-sm {
    padding: 0.25rem 0.6rem;
    font-size: 0.8rem;
}

.btn-icon {
    background: none;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    padding: 0.4rem 0.6rem;
    cursor: pointer;
}
.btn-icon:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

/* Cards & Grid */
.card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.25rem;
    box-shadow: var(--shadow);
}

.card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--border-color);
}

.card-title {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--text-primary);
}

.grid-cards {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1.25rem;
}

/* Badges */
.badge {
    display: inline-block;
    padding: 0.2rem 0.55rem;
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: 12px;
}
.badge-success { background-color: #2ea04326; color: #3fb950; }
.badge-warning { background-color: #d2992226; color: #e3b341; }
.badge-danger { background-color: #f8514926; color: #f85149; }
.badge-info { background-color: #388bfd26; color: #58a6ff; }
.badge-secondary { background-color: #6e768126; color: #8b949e; }
.badge-primary { background-color: #a371f726; color: #d2a8ff; }

/* Alerts */
.flash-messages {
    margin-bottom: 1.25rem;
}
.alert {
    padding: 0.75rem 1rem;
    border-radius: var(--radius-sm);
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.9rem;
}
.alert-success { background-color: #2ea04326; border: 1px solid #2ea04366; color: #3fb950; }
.alert-danger { background-color: #f8514926; border: 1px solid #f8514966; color: #f85149; }
.alert-warning { background-color: #d2992226; border: 1px solid #d2992266; color: #e3b341; }
.alert-info { background-color: #388bfd26; border: 1px solid #388bfd66; color: #58a6ff; }
.alert-close { background: none; border: none; color: inherit; cursor: pointer; font-size: 1rem; }

/* Forms */
.form-group {
    margin-bottom: 1rem;
}
.form-label {
    display: block;
    margin-bottom: 0.4rem;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
}
.form-control {
    width: 100%;
    padding: 0.5rem 0.75rem;
    font-size: 0.9rem;
    font-family: inherit;
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    outline: none;
    transition: border-color 0.15s ease;
}
.form-control:focus {
    border-color: var(--accent);
}
textarea.form-control {
    resize: vertical;
    min-height: 100px;
}

/* Tables */
.table-responsive {
    overflow-x: auto;
}
.table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
}
.table th, .table td {
    padding: 0.75rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}
.table th {
    background-color: var(--bg-tertiary);
    color: var(--text-secondary);
    font-weight: 600;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}
.table tbody tr:hover {
    background-color: var(--bg-tertiary);
}

/* IDE / Assignment Workspace Layout */
.ide-container {
    display: grid;
    grid-template-columns: 420px 1fr;
    gap: 1rem;
    height: calc(100vh - 120px);
    min-height: 650px;
}

.ide-task-pane {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.ide-pane-header {
    padding: 0.75rem 1rem;
    background-color: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.ide-task-content {
    padding: 1.25rem;
    overflow-y: auto;
    flex: 1;
}

.ide-task-content h1, .ide-task-content h2, .ide-task-content h3 {
    margin-top: 1rem;
    margin-bottom: 0.5rem;
}
.ide-task-content p {
    margin-bottom: 0.75rem;
}
.ide-task-content pre {
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    padding: 0.6rem 0.8rem;
    border-radius: var(--radius-sm);
    font-family: var(--font-mono);
    font-size: 0.85rem;
    overflow-x: auto;
    margin-bottom: 0.75rem;
}
.ide-task-content code {
    font-family: var(--font-mono);
    background-color: var(--bg-tertiary);
    padding: 0.15rem 0.35rem;
    border-radius: 4px;
    font-size: 0.85rem;
}

.ide-editor-pane {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    height: 100%;
}

.editor-card {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.editor-toolbar {
    padding: 0.5rem 1rem;
    background-color: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.editor-toolbar-actions {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

#monacoEditor {
    flex: 1;
    min-height: 250px;
    width: 100%;
}

/* Console & Test Results Panel */
.console-card {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    height: 260px;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.tabs-nav {
    display: flex;
    background-color: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
    padding: 0 0.5rem;
}

.tab-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    padding: 0.5rem 0.85rem;
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    border-bottom: 2px solid transparent;
}
.tab-btn.active {
    color: var(--accent);
    border-bottom-color: var(--accent);
}

.tab-pane {
    display: none;
    padding: 0.75rem 1rem;
    flex: 1;
    overflow-y: auto;
}
.tab-pane.active {
    display: block;
}

.console-output {
    background-color: #05070a;
    color: #c9d1d9;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    padding: 0.75rem;
    border-radius: var(--radius-sm);
    min-height: 120px;
    white-space: pre-wrap;
    word-break: break-all;
    border: 1px solid var(--border-color);
}

.test-result-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.5rem 0.75rem;
    background-color: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    margin-bottom: 0.4rem;
    font-size: 0.85rem;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.stat-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.25rem;
}
.stat-value {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--accent);
    margin-top: 0.25rem;
}
.stat-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

@media (max-width: 992px) {
    .ide-container {
        grid-template-columns: 1fr;
        height: auto;
    }
}