:root {
    --primary: #4f46e5;
    --primary-hover: #4338ca;
    --secondary: #64748b;
    --secondary-hover: #475569;
    --danger: #ef4444;
    --danger-hover: #dc2626;
    --success: #10b981;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
}

/* Login Container */
.login-container {
    max-width: 400px;
    margin: 100px auto;
    background: var(--card-bg);
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    border: 1px solid var(--border-color);
}

.login-container h1 {
    text-align: center;
    margin-top: 0;
    margin-bottom: 2rem;
    font-weight: 700;
    color: var(--text-main);
}

/* Navigation Bar */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
    color: white;
    padding: 1rem 2.5rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.navbar h2 {
    margin: 0;
    font-weight: 600;
    letter-spacing: -0.5px;
}

.nav-left, .nav-right {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

/* Container */
.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 2.5rem 1.5rem;
}

/* Cards */
.card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 1.5rem 2rem;
    margin-bottom: 2rem;
    border: 1px solid var(--border-color);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03);
    transition: box-shadow 0.2s ease, transform 0.2s ease;
}

.card:hover {
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

.card h3 {
    margin-top: 0;
    font-weight: 600;
    color: var(--text-main);
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.75rem;
    margin-bottom: 1.25rem;
}

/* Forms */
.form-group {
    margin-bottom: 1.25rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    font-size: 0.95rem;
    color: var(--text-muted);
}

.form-group input, .form-group select {
    width: 100%;
    padding: 0.65rem 0.8rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    box-sizing: border-box;
    font-family: inherit;
    transition: border-color 0.15s, box-shadow 0.15s;
    background-color: #fcfcfc;
}

.form-group input:focus, .form-group select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
    background-color: #fff;
}

/* Buttons */
.btn {
    padding: 0.65rem 1.25rem;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    transition: background-color 0.2s, transform 0.1s;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-family: inherit;
}

.btn:active:not(:disabled) {
    transform: translateY(1px);
}

.btn-primary {
    background-color: var(--primary);
    color: white;
}

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

.btn-secondary {
    background-color: var(--secondary);
    color: white;
}

.btn-secondary:hover:not(:disabled) {
    background-color: var(--secondary-hover);
}

.btn-danger {
    background-color: var(--danger);
    color: white;
}

.btn-danger:hover:not(:disabled) {
    background-color: var(--danger-hover);
}

.btn-sm {
    padding: 0.35rem 0.75rem;
    font-size: 0.85rem;
}

/* Training Card */
.training-card {
    border-left: 4px solid var(--primary);
    padding: 1.5rem;
    margin: 1.25rem 0;
    background-color: #ffffff;
    border-radius: 8px;
    border-top: 1px solid var(--border-color);
    border-right: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
    box-shadow: 0 2px 5px rgba(0,0,0,0.02);
    transition: box-shadow 0.2s ease, transform 0.2s ease;
}

.training-card:hover {
    box-shadow: 0 6px 12px rgba(0,0,0,0.06);
    transform: translateY(-2px);
}

.training-card h4 {
    margin: 0 0 0.5rem 0;
    font-size: 1.4rem;
    color: var(--text-main);
    display: flex;
    align-items: center;
    gap: 8px;
}

/* Inline Form */
.inline-form {
    display: flex;
    flex-direction: row;
    gap: 0.75rem;
    margin-bottom: 0.75rem;
    align-items: center;
}

.inline-form input {
    padding: 0.4rem 0.6rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    flex-grow: 1;
}

.inline-form input:focus {
    outline: none;
    border-color: var(--primary);
}

/* Dropdown */
.dropdown {
    position: relative;
}

.dropdown-menu {
    position: absolute;
    right: 0;
    top: 110%;
    background: white;
    box-shadow: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);
    z-index: 100;
    min-width: 250px;
    border-radius: 8px;
    color: #333;
    overflow: hidden;
    border: 1px solid var(--border-color);
}

.dropdown-item {
    padding: 0.8rem 1.2rem;
    cursor: pointer;
    border-bottom: 1px solid var(--border-color);
    transition: background-color 0.15s;
    font-size: 0.95rem;
}

.dropdown-item:last-child {
    border-bottom: none;
}

.dropdown-item:hover {
    background: #f1f5f9;
}

/* Impersonation Banner */
.impersonation-banner {
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
    color: white;
    padding: 0.5rem 1.25rem;
    border-radius: 20px;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-weight: 500;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    font-size: 0.9rem;
}

.impersonation-banner .btn {
    background: rgba(255,255,255,0.2);
    color: white;
}

.impersonation-banner .btn:hover {
    background: rgba(255,255,255,0.3);
}

/* Badges and Text */
.badge {
    display: inline-block;
    background-color: var(--border-color);
    padding: 2px 10px;
    border-radius: 12px;
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 600;
}

.error {
    color: var(--danger);
    margin-top: 0.5rem;
    font-size: 0.9rem;
}

.success {
    color: var(--success);
    margin-top: 0.5rem;
    font-size: 0.9rem;
}

.text-muted {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin: 0.25rem 0;
}

/* Challenges and Markdown */
.challenges-list {
    list-style: none;
    padding: 0;
}

.challenges-list li {
    margin-bottom: 0.5rem;
}

.challenges-list a {
    color: var(--primary);
    text-decoration: none;
}

.challenges-list a:hover {
    text-decoration: underline;
}

.markdown-body {
    background: white;
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgba(0,0,0,0.05);
    max-width: 100%;
    overflow-x: auto;
    margin-top: 1rem;
    line-height: 1.7;
    border: 1px solid var(--border-color);
    font-size: 1.05rem;
}

.markdown-body pre {
    background: #1e293b;
    color: #e2e8f0;
    padding: 1.25rem;
    border-radius: 8px;
    overflow-x: auto;
}

.markdown-body code {
    background: #f1f5f9;
    padding: 0.2em 0.4em;
    border-radius: 4px;
    font-family: ui-monospace, SFMono-Regular, Consolas, "Liberation Mono", Menlo, monospace;
}

.markdown-body pre code {
    background: transparent;
    padding: 0;
}

/* Challenge Progression & Users */
.challenges-layout {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 25px;
}

.challenge-tab {
    padding: 12px 18px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--card-bg);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    color: var(--text-main);
    font-weight: 500;
    transition: all 0.2s ease;
    box-shadow: 0 1px 2px rgba(0,0,0,0.05);
}

.challenge-tab.completed {
    border-color: var(--success);
    background-color: #f0fdf4;
    color: #166534;
}

.challenge-tab.in-progress {
    border-color: var(--primary);
    background-color: #eef2ff;
    color: var(--primary-hover);
    font-weight: 600;
    box-shadow: 0 0 0 2px rgba(79, 70, 229, 0.2);
}

.challenge-tab.locked {
    border-color: var(--border-color);
    background-color: #f8fafc;
    color: #94a3b8;
    cursor: not-allowed;
    box-shadow: none;
}

.challenge-tab:hover:not(.locked) {
    transform: translateY(-2px);
    box-shadow: 0 4px 6px -1px rgba(0,0,0,0.1);
}

.overview-section {
    margin-bottom: 25px;
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    border: 1px solid var(--border-color);
}

.overview-section summary {
    cursor: pointer;
    font-weight: 600;
    outline: none;
    user-select: none;
    display: flex;
    align-items: center;
}

.overview-section summary h3 {
    display: inline;
    margin: 0 0 0 10px;
    border-bottom: none;
    padding-bottom: 0;
}

.user-list-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: #fafafa;
    transition: background-color 0.2s;
}

.user-list-item:hover {
    background-color: white;
    box-shadow: 0 2px 4px rgba(0,0,0,0.02);
}


/* Expand/Collapse Overview */
.overview-container {
    position: relative;
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    border: 1px solid var(--border-color);
    margin-bottom: 0px;
    transition: max-height 0.3s ease;
}
.overview-container.collapsed {
    max-height: 200px;
    overflow: hidden;
}
.overview-container.expanded {
    max-height: 5000px; /* large enough for any overview */
    overflow: visible;
}
.overview-fade {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 100px;
    background: linear-gradient(to bottom, rgba(255,255,255,0), rgba(255,255,255,1));
    display: none;
}
.overview-container.collapsed .overview-fade {
    display: block;
}

/* Utility Classes */
.w-100 {
    width: 100%;
}
.icon {
    margin-right: 8px;
    font-size: 1.1em;
    vertical-align: text-bottom;
}

/* Dashboard Layout Grid */
.dashboard-wrapper {
    animation: fadeIn 0.3s ease-out;
}

.dashboard-header {
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.dashboard-header h2 {
    margin: 0 0 0.25rem 0;
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-main);
    letter-spacing: -0.5px;
}

.dashboard-header .text-muted {
    font-size: 1.05rem;
}

.dashboard-grid-2col {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    align-items: start;
}

@media (min-width: 992px) {
    .dashboard-grid-2col {
        grid-template-columns: 1fr 1fr;
    }
}

.card.action-card {
    background: #f8fafc; /* slightly different tint to distinguish input areas */
    box-shadow: inset 0 2px 4px 0 rgba(0, 0, 0, 0.02);
}

.card.data-card {
    border-top: 4px solid var(--primary);
    padding: 2rem;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.75rem;
    margin-bottom: 1.5rem;
}

.card-header h3 {
    margin: 0;
    border-bottom: none;
    padding-bottom: 0;
}

.user-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 10px;
}

.pagination-controls {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-top: 20px;
    align-items: center;
    padding-top: 15px;
    border-top: 1px dashed var(--border-color);
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(5px); }
    to { opacity: 1; transform: translateY(0); }
}
.markdown-scroll-box {
    max-height: 60vh;
    overflow-y: auto;
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgba(0,0,0,0.05);
    border: 1px solid var(--border-color);
}
.markdown-scroll-box::-webkit-scrollbar {
    width: 8px;
}
.markdown-scroll-box::-webkit-scrollbar-track {
    background: #f1f5f9;
    border-radius: 0 12px 12px 0;
}
.markdown-scroll-box::-webkit-scrollbar-thumb {
    background: #0ea5e9;
    border-radius: 4px;
}

.challenge-header-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: #f1f5f9;
    padding: 10px;
    border-radius: 8px;
    margin-bottom: 15px;
}

/* Nested Collapses */
details.nested-collapse {
    background: #f8fafc;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 12px 16px;
    margin-bottom: 12px;
    transition: background 0.2s;
}
details.nested-collapse:hover {
    background: #f1f5f9;
}
details.nested-collapse summary {
    font-weight: 600;
    cursor: pointer;
    outline: none;
    color: var(--text-main);
    display: flex;
    align-items: center;
}
details.nested-collapse summary::before {
    content: '▶';
    font-size: 0.8em;
    margin-right: 8px;
    color: var(--text-muted);
    transition: transform 0.2s;
}
details.nested-collapse[open] summary::before {
    transform: rotate(90deg);
}
details.nested-collapse summary::-webkit-details-marker {
    display: none;
}
details.nested-collapse[open] summary {
    margin-bottom: 12px;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 8px;
}