/* ========================================
   Chat Section - Side Panel
======================================== */
.chat-section {
    display: flex;
    flex-direction: column;
    width: 360px;
    background: var(--bg-base);
    flex-shrink: 0;
    position: relative;
    overflow: hidden;
    min-height: 0;
}

.chat-section.hidden {
    display: none;
}

/* ========================================
   Chat Header
======================================== */
.chat-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-4) var(--space-5);
    height: 64px;
    flex-shrink: 0;
}

.chat-header-left {
    display: flex;
    align-items: center;
    gap: var(--space-3);
}

.chat-collapse-btn {
    width: 32px;
    height: 32px;
    border-radius: var(--radius-md);
    background: transparent;
    color: var(--text-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-fast);
}

.chat-collapse-btn:hover {
    background: var(--bg-hover);
    color: var(--text-secondary);
}

.chat-collapse-btn svg {
    width: 18px;
    height: 18px;
}

.tutor-avatar {
    width: 36px;
    height: 36px;
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-hover) 100%);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
}

.tutor-avatar svg {
    width: 18px;
    height: 18px;
    stroke: var(--accent-text);
}

.tutor-info h2 {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-primary);
}

.tutor-info .status {
    font-size: 12px;
    color: var(--text-tertiary);
}

/* ========================================
   Chat Body
======================================== */
.chat-body {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-height: 0;
    padding: 0 var(--space-4);
}

/* Messages Container */
.chat-messages {
    flex: 1;
    overflow-y: auto;
    padding: var(--space-4) 0;
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
    min-height: 0;
}

/* Message Bubble */
.message {
    display: flex;
    gap: var(--space-3);
    animation: fadeIn 0.2s ease;
}

.message-avatar {
    width: 28px;
    height: 28px;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.message-avatar svg {
    width: 14px;
    height: 14px;
    stroke: var(--text-tertiary);
}

.message-content {
    flex: 1;
    padding: var(--space-2) 0;
    background: transparent;
    font-size: 13px;
    line-height: 1.7;
    color: var(--text-primary);
}

.message-content p {
    margin-bottom: var(--space-2);
}

.message-content p:last-child {
    margin-bottom: 0;
}

/* User Message */
.message.user {
    flex-direction: row-reverse;
}

.message.user .message-content {
    background: transparent;
    color: var(--text-secondary);
    text-align: right;
}

.message.user .message-avatar {
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-hover) 100%);
}

.message.user .message-avatar svg {
    stroke: var(--accent-text);
}

/* ========================================
   Chat Input Area
======================================== */
.chat-input-area {
    display: flex;
    gap: var(--space-2);
    padding: var(--space-4) 0;
}

#chatInput {
    flex: 1;
    padding: var(--space-3) var(--space-4);
    border-radius: var(--radius-md);
    background: var(--bg-hover);
    font-size: 13px;
    color: var(--text-primary);
    transition: var(--transition-fast);
}

[data-theme="dark"] #chatInput {
    background: rgba(255, 255, 255, 0.03);
}

#chatInput:focus {
    background: var(--bg-active);
}

[data-theme="dark"] #chatInput:focus {
    background: rgba(255, 255, 255, 0.06);
}

#chatInput::placeholder {
    color: var(--text-placeholder);
}

.send-btn {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-lg);
    background: var(--accent);
    color: var(--accent-text);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-fast);
}

.send-btn:hover:not(:disabled) {
    opacity: 0.9;
}

.send-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

.send-btn svg {
    width: 18px;
    height: 18px;
}

/* ========================================
   Follow-up Suggestion Chips
======================================== */
.follow-up-suggestions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2);
    padding: var(--space-3) 0 var(--space-1);
    animation: fadeIn 0.3s ease;
}

.suggestion-chip {
    padding: var(--space-2) var(--space-3);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-default);
    background: var(--bg-secondary);
    color: var(--text-secondary);
    font-size: 12px;
    line-height: 1.4;
    cursor: pointer;
    transition: var(--transition-fast);
    text-align: left;
    max-width: 100%;
}

.suggestion-chip:hover {
    background: var(--bg-hover);
    border-color: var(--accent);
    color: var(--text-primary);
}

.suggestion-chip:active {
    transform: scale(0.97);
}

/* ========================================
   KaTeX Math Rendering
======================================== */
.katex-mathml {
    position: absolute;
    clip: rect(1px, 1px, 1px, 1px);
    padding: 0;
    border: 0;
    height: 1px;
    width: 1px;
    overflow: hidden;
}

.katex {
    color: inherit;
    font-size: 1.05em;
}

.katex-display {
    margin: 0.75em 0;
    padding: 0.25em 0;
    overflow-x: auto;
    overflow-y: visible;
    -webkit-overflow-scrolling: touch;
    max-width: 100%;
}

.katex-display > .katex {
    white-space: nowrap;
}

.katex {
    overflow-wrap: break-word;
    max-width: 100%;
}

.md-content p > .katex-display:only-child {
    margin-top: 0;
    margin-bottom: 0;
}

.katex .frac-line {
    border-bottom-width: 0.04em;
}

.katex .mfrac .frac-line {
    min-width: 100%;
}

/* ========================================
   Rich Markdown Content
======================================== */
.md-content {
    line-height: 1.75;
    word-wrap: break-word;
    overflow-wrap: break-word;
}

.md-content > *:first-child {
    margin-top: 0;
}

.md-content > *:last-child {
    margin-bottom: 0;
}

/* Headings */
.md-content h1,
.md-content h2,
.md-content h3 {
    color: var(--text-primary);
    font-weight: 700;
    line-height: 1.3;
    margin-top: 1.4em;
    margin-bottom: 0.6em;
}

.md-content h1 { font-size: 1.35em; }
.md-content h2 { font-size: 1.2em; }
.md-content h3 { font-size: 1.05em; }

.md-content > h1:first-child,
.md-content > h2:first-child,
.md-content > h3:first-child {
    margin-top: 0;
}

/* Paragraphs */
.md-content p {
    margin: 0 0 0.75em;
}

.md-content p:last-child {
    margin-bottom: 0;
}

/* Lists */
.md-content ol,
.md-content ul {
    margin: 0.5em 0 1em;
    padding-left: 1.5em;
}

.md-content li {
    margin-bottom: 0.35em;
    line-height: 1.65;
}

.md-content li > p {
    margin-bottom: 0.3em;
}

.md-content ol ol,
.md-content ul ul,
.md-content ol ul,
.md-content ul ol {
    margin-top: 0.25em;
    margin-bottom: 0.25em;
}

/* Bold & italic */
.md-content strong {
    font-weight: 600;
    color: var(--text-primary);
}

.md-content em {
    font-style: italic;
}

/* Inline code */
.md-content code {
    background: var(--bg-hover);
    padding: 0.15em 0.4em;
    border-radius: var(--radius-sm);
    font-size: 0.9em;
    font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
    color: var(--text-primary);
}

/* Code blocks */
.md-content pre {
    background: var(--bg-secondary);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    padding: var(--space-3) var(--space-4);
    overflow-x: auto;
    margin: 0.75em 0;
    font-size: 0.875em;
    line-height: 1.6;
}

.md-content pre code {
    background: transparent;
    padding: 0;
    border-radius: 0;
    font-size: inherit;
}

/* Horizontal rule */
.md-content hr {
    border: none;
    border-top: 1px solid var(--border-default);
    margin: 1.25em 0;
}

/* Callout boxes */
.callout {
    border-radius: var(--radius-md);
    padding: var(--space-3) var(--space-4);
    margin: 0.75em 0;
    border-left: 4px solid;
}

.callout > *:first-child {
    margin-top: 0;
}

.callout > *:last-child {
    margin-bottom: 0;
}

.callout p {
    margin: 0.3em 0;
}

.callout-info {
    background: rgba(234, 179, 8, 0.08);
    border-left-color: #eab308;
    color: var(--text-primary);
}

[data-theme="dark"] .callout-info {
    background: rgba(234, 179, 8, 0.1);
}

.callout-warning {
    background: rgba(239, 68, 68, 0.08);
    border-left-color: #ef4444;
    color: var(--text-primary);
}

[data-theme="dark"] .callout-warning {
    background: rgba(239, 68, 68, 0.1);
}

.callout-tip {
    background: rgba(34, 197, 94, 0.08);
    border-left-color: #22c55e;
    color: var(--text-primary);
}

[data-theme="dark"] .callout-tip {
    background: rgba(34, 197, 94, 0.1);
}

/* Tables */
.md-content .table-wrap {
    overflow-x: auto;
    margin: 1em 0;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-default);
}

.md-content table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.875em;
    white-space: nowrap;
}

.md-content th,
.md-content td {
    padding: 10px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border-default);
}

.md-content th {
    background: var(--bg-secondary);
    font-weight: 600;
    font-size: 0.8em;
    text-transform: uppercase;
    letter-spacing: 0.03em;
    color: var(--text-secondary);
}

.md-content td {
    color: var(--text-primary);
}

.md-content tbody tr:last-child td {
    border-bottom: none;
}

.md-content tbody tr:hover {
    background: var(--bg-hover);
}

[data-theme="dark"] .md-content th {
    background: var(--bg-elevated);
}

[data-theme="dark"] .md-content .table-wrap {
    border-color: rgba(255, 255, 255, 0.08);
}

/* ========================================
   Math Symbol Keyboard
======================================== */
.math-keyboard {
    background: var(--bg-elevated);
    border-radius: var(--radius-lg);
    padding: var(--space-2) var(--space-3) var(--space-3);
    margin-bottom: var(--space-2);
    box-shadow: var(--shadow-md);
}

.math-kb-tabs {
    display: flex;
    gap: 2px;
    margin-bottom: var(--space-2);
    padding-bottom: var(--space-2);
    border-bottom: 1px solid var(--bg-active);
    align-items: center;
}

.math-kb-close {
    margin-left: auto;
    width: 26px;
    height: 26px;
    min-width: 26px;
    border-radius: var(--radius-sm);
    background: transparent;
    color: var(--text-secondary);
    font-size: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    flex-shrink: 0;
    transition: var(--transition-fast);
}

.math-kb-close:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

.math-kb-tab {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1px;
    padding: var(--space-1) var(--space-3);
    border-radius: var(--radius-sm) var(--radius-sm) 0 0;
    background: transparent;
    color: var(--text-secondary);
    font-size: 10px;
    font-weight: 600;
    line-height: 1.3;
    transition: var(--transition-fast);
    border-bottom: 2px solid transparent;
    white-space: nowrap;
    cursor: pointer;
}

.math-kb-tab:hover {
    color: var(--text-primary);
    background: var(--bg-hover);
}

.math-kb-tab.active {
    color: var(--accent);
    border-bottom-color: var(--accent);
}

.math-kb-panel {
    /* visible by default, toggled via .hidden */
}

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

.math-kb-btn {
    min-height: 34px;
    padding: 2px 1px;
    border-radius: var(--radius-sm);
    background: var(--bg-elevated);
    color: var(--text-primary);
    font-size: 12px;
    font-weight: 500;
    text-align: center;
    transition: var(--transition-fast);
    font-family: inherit;
    cursor: pointer;
    line-height: 1.2;
    overflow: hidden;
    white-space: nowrap;
    text-overflow: ellipsis;
}

.math-kb-btn:hover {
    background: var(--bg-active);
}

.math-kb-btn:active {
    transform: scale(0.93);
}

.math-kb-number {
    background: var(--accent);
    color: var(--accent-text);
}

.math-kb-number:hover {
    background: var(--accent-hover);
    color: var(--accent-text);
}

/* Toggle button */
.math-kb-toggle {
    width: 34px;
    height: 34px;
    min-width: 34px;
    border-radius: var(--radius-md);
    background: transparent;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-fast);
    flex-shrink: 0;
    cursor: pointer;
}

.math-kb-toggle:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

.math-kb-toggle.active {
    background: var(--accent-subtle);
    color: var(--accent);
}

.math-kb-toggle svg {
    width: 17px;
    height: 17px;
    stroke: currentColor;
}

/* Responsive: shrink grid on small screens */
@media (max-width: 560px) {
    .math-kb-grid {
        grid-template-columns: repeat(7, minmax(0, 1fr));
    }
    .math-kb-tab {
        padding: var(--space-1) var(--space-2);
        font-size: 9px;
    }
    .math-kb-tabs {
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        scrollbar-width: none;
    }
    .math-kb-tabs::-webkit-scrollbar {
        display: none;
    }
}

@media (max-width: 900px) {
    .chat-section {
        border-top: 1px solid var(--border-subtle);
    }
}

@media (max-width: 600px) {
    .message-content {
        font-size: 14px;
    }

    .md-content pre {
        font-size: 0.8em;
        padding: var(--space-2) var(--space-3);
    }

    .md-content th,
    .md-content td {
        padding: 8px 10px;
        font-size: 0.8em;
    }

    .md-content table {
        font-size: 0.8em;
    }

    .katex-display {
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }

    .math-keyboard {
        padding: var(--space-2);
        border-radius: var(--radius-md);
    }
}