:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary: #f3f4f6;
    --text-main: #1f2937;
    --text-muted: #6b7280;
    --bg-main: #f8fafc;
    --bg-card: #ffffff;
    --success: #10b981;
    --success-bg: #d1fae5;
    --error: #ef4444;
    --error-bg: #fee2e2;
    --warning: #f59e0b;
    --border: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --radius: 0.5rem;
}

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

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

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* Header */
.header {
    background-color: var(--bg-card);
    border-bottom: 1px solid var(--border);
    padding: 1rem 0;
    margin-bottom: 2rem;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
}

.nav-link {
    color: var(--text-muted);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

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

/* Cards */
.card {
    background: var(--bg-card);
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    border: 1px solid var(--border);
}

/* Forms */
.form-group {
    margin-bottom: 1rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-main);
}

.form-control {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-family: inherit;
    font-size: 1rem;
    transition: border-color 0.2s;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius);
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    border: none;
    transition: all 0.2s;
}

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

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

.w-100 {
    width: 100%;
}

/* Utilities */
.hidden {
    display: none !important;
}

.mt-4 {
    margin-top: 1.5rem;
}

.mb-4 {
    margin-bottom: 1.5rem;
}

.text-muted {
    color: var(--text-muted);
}

.text-warning {
    color: var(--warning);
}

/* Loading Spinner */
.spinner {
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255,255,255,0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
    margin-left: 10px;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Response Section */
.response-section h3 {
    margin-bottom: 1rem;
    color: var(--text-main);
}

.thinking-container {
    margin-bottom: 1.5rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
}

.toggle-btn {
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    background: var(--secondary);
    border: none;
    cursor: pointer;
    font-weight: 500;
    color: var(--text-main);
}

.toggle-btn:hover {
    background: #e5e7eb;
}

.chevron {
    transition: transform 0.3s;
}

.toggle-btn.active .chevron {
    transform: rotate(180deg);
}

.thinking-content {
    padding: 1rem;
    background: #fcfcfc;
    border-top: 1px solid var(--border);
    font-size: 0.95rem;
    color: var(--text-muted);
}

.step {
    position: relative;
    padding-left: 2rem;
    margin-bottom: 1rem;
}

.step::before {
    content: counter(step-counter);
    counter-increment: step-counter;
    position: absolute;
    left: 0;
    top: 0;
    width: 1.5rem;
    height: 1.5rem;
    background: var(--primary);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    font-weight: bold;
}

.step:last-child {
    margin-bottom: 0;
}

.thinking-content {
    counter-reset: step-counter;
}

.final-answer-box {
    background: var(--success-bg);
    border: 1px solid var(--success);
    border-radius: var(--radius);
    padding: 1.5rem;
    text-align: center;
}

.final-answer-box h4 {
    color: var(--success);
    margin-bottom: 0.5rem;
    text-transform: uppercase;
    font-size: 0.85rem;
    letter-spacing: 0.05em;
}

.final-answer-text {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-main);
}

/* History */
.history-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.history-item {
    background: var(--bg-card);
    padding: 1rem;
    border-radius: var(--radius);
    border: 1px solid var(--border);
}

.history-topic {
    font-size: 0.8rem;
    background: var(--secondary);
    padding: 0.2rem 0.5rem;
    border-radius: 1rem;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
    display: inline-block;
}

/* Dashboard Specific */
.dashboard-main {
    max-width: 1200px;
}

.filter-controls {
    display: flex;
    gap: 1rem;
    align-items: flex-end;
}

.filter-controls .form-group {
    margin-bottom: 0;
    flex: 1;
}

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

.stat-title {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-main);
}

.dashboard-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

.table-responsive {
    overflow-x: auto;
}

.data-table {
    width: 100%;
    border-collapse: collapse;
}

.data-table th, .data-table td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

.data-table th {
    font-weight: 600;
    color: var(--text-muted);
    background-color: var(--secondary);
}

.status-badge {
    display: inline-block;
    padding: 0.25rem 0.5rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 600;
}

.status-correct {
    background-color: var(--success-bg);
    color: var(--success);
}

.status-incorrect {
    background-color: var(--error-bg);
    color: var(--error);
}

/* Responsive */
@media (max-width: 768px) {
    .dashboard-grid {
        grid-template-columns: 1fr;
    }
    .filter-controls {
        flex-direction: column;
        align-items: stretch;
    }
}