:root {
    color-scheme: light;
    --primary: #3870e7;
    --primary-hover: #2856c7;
    --primary-soft: #e0e9ff;
    --success: #16a34a;
    --success-soft: #dcfce7;
    --danger: #dc2626;
    --danger-hover: #b91c1c;
    --danger-soft: #fee2e2;
    --bg: #f3f6f8;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --surface: #ffffff;
    --surface-alt: #f8fafc;
    --edit-bg: #fffde7;
    --toast-bg: #0f172a;
    --toast-text: #ffffff;
    --spinner-track: #e2e8f0;
    --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.04), 0 1px 3px rgba(15, 23, 42, 0.06);
    --shadow-md: 0 4px 12px rgba(15, 23, 42, 0.08);
    --shadow-lg: 0 12px 32px rgba(15, 23, 42, 0.14);
    --header-gradient: linear-gradient(135deg, #3870e7 0%, #6b8eff 100%);
    --goal-bg: #fffbeb;
    --goal-border: #fef3c7;
    --goal-text: #92400e;
}

[data-theme="dark"] {
    color-scheme: dark;
    --primary: #7da0ff;
    --primary-hover: #9ab4ff;
    --primary-soft: #1e2a4a;
    --success: #22c55e;
    --success-soft: #14532d;
    --danger: #f87171;
    --danger-hover: #fca5a5;
    --danger-soft: #3f1d1d;
    --bg: #0b1220;
    --text-main: #e2e8f0;
    --text-muted: #94a3b8;
    --border: #1f2937;
    --surface: #111827;
    --surface-alt: #0f172a;
    --edit-bg: #3f2a06;
    --toast-bg: #f1f5f9;
    --toast-text: #0f172a;
    --spinner-track: #1f2937;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.5);
    --shadow-lg: 0 12px 32px rgba(0, 0, 0, 0.6);
    --header-gradient: linear-gradient(135deg, #1e3a8a 0%, #3870e7 100%);
    --goal-bg: #2a210a;
    --goal-border: #4a3a14;
    --goal-text: #fbbf24;
}

* { box-sizing: border-box; }

html, body {
    background: var(--bg);
    margin: 0 !important;
    padding: 0 !important;
    width: 100%;
    height: 100%;
    display: block;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    color: var(--text-main);
    line-height: 1.5;
    accent-color: var(--primary);
    transition: background-color 0.2s ease, color 0.2s ease;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Header */
.top-header {
    width: 100%;
    margin:0;
    background: var(--header-gradient);
    color: #ffffff;
    padding: 56px 0 48px;
    text-align: center;
    box-shadow: var(--shadow-md);
}
.top-header h1 {
    margin: 0 0 8px;
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.01em;
}
.top-header p {
    margin: 0;
    opacity: 0.92;
    font-size: 1rem;
}

/* Tab nav */
.tab-nav {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    margin-bottom: 32px;
    position: sticky;
    top: 0;
    z-index: 10;
}
.nav-wrapper {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 64px;
}
.tabs-group {
    display: flex;
    gap: 4px;
}
.tab-btn {
    background: none;
    border: none;
    padding: 20px 18px;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--text-muted);
    border-bottom: 3px solid transparent;
    margin-bottom: -1px;
    transition: color 0.15s ease, border-color 0.15s ease;
}
.tab-btn:hover { color: var(--text-main); }
.tab-btn.active {
    color: var(--primary);
    border-bottom-color: var(--primary);
}

.utilities-group {
    display: flex;
    align-items: center;
    gap: 12px;
}

.btn-icon-toggle {
    background: var(--surface-alt);
    border: 1px solid var(--border);
    border-radius: 50%;
    width: 38px;
    height: 38px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1rem;
    transition: background-color 0.15s ease, transform 0.15s ease, border-color 0.15s ease;
}
.btn-icon-toggle:hover {
    background: var(--primary-soft);
    border-color: var(--primary);
    transform: translateY(-1px);
}

.auth-btn { display: flex; gap: 8px; }

.btn-login {
    background: none;
    border: 1px solid transparent;
    padding: 8px 16px;
    border-radius: 8px;
    color: var(--text-main);
    font-weight: 600;
    cursor: pointer;
    font-size: 0.9rem;
    transition: background-color 0.15s ease;
}
.btn-login:hover { background: var(--primary-soft); }

.btn-signup {
    background: var(--primary);
    color: #ffffff;
    border: none;
    padding: 8px 18px;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    font-size: 0.9rem;
    box-shadow: var(--shadow-sm);
    transition: background-color 0.15s ease, transform 0.15s ease, box-shadow 0.15s ease;
}
.btn-signup:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-logout {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: transparent;
    color: var(--text-muted);
    border: 1px solid var(--border);
    padding: 8px 14px;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    transition: background-color 0.15s ease, color 0.15s ease, border-color 0.15s ease, transform 0.15s ease, box-shadow 0.15s ease;
}
.btn-logout .btn-logout-icon {
    transition: transform 0.2s ease;
}
.btn-logout:hover {
    background: var(--danger-soft);
    color: var(--danger);
    border-color: var(--danger);
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}
.btn-logout:hover .btn-logout-icon {
    transform: translateX(2px);
}
.btn-logout:active {
    transform: translateY(0);
    background: var(--danger);
    color: #ffffff;
    border-color: var(--danger-hover);
}
.btn-logout:focus-visible {
    outline: 2px solid var(--danger);
    outline-offset: 2px;
}
.btn-logout[hidden] { display: none; }

/* Cards */
.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 28px;
    margin-bottom: 20px;
    box-shadow: var(--shadow-sm);
}
.card h3 {
    margin: 0 0 20px;
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-main);
}

.control-row {
    display: flex;
    align-items: flex-end;
    gap: 20px;
    flex-wrap: wrap;
}
.input-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
    flex: 1;
    min-width: 180px;
}
.input-group label {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-muted);
}
.input-group select {
    appearance: none;
    background-color: var(--surface);
    color: var(--text-main);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 10px 36px 10px 14px;
    font-size: 0.95rem;
    font-weight: 500;
    font-family: inherit;
    cursor: pointer;
    background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'><polyline points='6 9 12 15 18 9'/></svg>");
    background-repeat: no-repeat;
    background-position: right 12px center;
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.input-group select:hover { border-color: var(--text-muted); }
.input-group select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-soft);
}

/* Empty state */
.empty-state {
    text-align: center;
    padding: 56px 20px;
    color: var(--text-muted);
}
.empty-state .icon {
    font-size: 2.5rem;
    margin-bottom: 12px;
    opacity: 0.6;
}
.empty-state h3 {
    margin: 0 0 6px;
    color: var(--text-main);
    font-size: 1.05rem;
    font-weight: 600;
}
.empty-state p { margin: 0; font-size: 0.9rem; }

/* Card header */
.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
    gap: 12px;
}
.badge {
    display: inline-block;
    background: var(--primary-soft);
    color: var(--primary);
    padding: 4px 12px;
    border-radius: 999px;
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 0.02em;
}
.badge.success {
    background: var(--success-soft);
    color: var(--success);
}

/* Math & edit */
.math-container {
    font-size: 1.15rem;
    line-height: 1.7;
    padding: 8px 0 16px;
    color: var(--text-main);
    overflow-wrap: break-word;
}
/* Let wide display equations scroll horizontally instead of overflowing the
   box. Applies everywhere MathJax renders (answer area + chatbot messages). */
mjx-container[display="true"] {
    overflow-x: auto;
    overflow-y: hidden;
    max-width: 100%;
}
.math-view[contenteditable="true"] {
    outline: 2px dashed var(--success);
    background: var(--edit-bg);
    padding: 12px;
    border-radius: 8px;
}
.math-view[contenteditable="true"]:focus {
    outline-style: solid;
    box-shadow: 0 0 0 3px var(--success-soft);
}
.edit-toolbar {
    background: var(--surface-alt);
    border: 1px solid var(--border);
    padding: 12px;
    border-radius: 10px;
    margin-top: 12px;
}
.toolbar-btns {
    display: flex;
    gap: 8px;
    justify-content: flex-end;
}

.action-bar { margin-top: 20px; }

/* Buttons */
button {
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    border: none;
    font-family: inherit;
}
.btn-primary {
    background: var(--primary);
    color: #ffffff;
    padding: 12px 24px;
    font-size: 0.95rem;
    box-shadow: var(--shadow-sm);
    transition: background-color 0.15s ease, transform 0.15s ease, box-shadow 0.15s ease;
}
.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}
.btn-primary:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
    box-shadow: var(--shadow-sm);
}
.btn-primary:disabled:hover {
    background: var(--primary); /* no hover effect while disabled */
    transform: none;
}
.btn-secondary {
    background: var(--success);
    color: #ffffff;
    padding: 12px 24px;
    width: 100%;
    font-size: 0.95rem;
    transition: opacity 0.15s ease, transform 0.15s ease;
}
.btn-secondary:hover { opacity: 0.92; transform: translateY(-1px); }

.btn-edit {
    background: none;
    color: var(--primary);
    text-decoration: none;
    padding: 6px 10px;
    font-size: 0.85rem;
    border-radius: 6px;
    transition: background-color 0.15s ease;
}
.btn-edit:hover { background: var(--primary-soft); }

.btn-cancel {
    background: var(--surface);
    color: var(--text-main);
    border: 1px solid var(--border);
    padding: 8px 16px;
    font-size: 0.9rem;
    transition: background-color 0.15s ease;
}
.btn-cancel:hover { background: var(--bg); }

.btn-submit {
    background: var(--success);
    color: #ffffff;
    padding: 8px 16px;
    font-size: 0.9rem;
    transition: opacity 0.15s ease;
}
.btn-submit:hover { opacity: 0.92; }

/* Toast */
.toast {
    position: fixed;
    bottom: 24px; right: 24px;
    background: var(--toast-bg);
    color: var(--toast-text);
    padding: 12px 22px;
    border-radius: 999px;
    box-shadow: var(--shadow-lg);
    display: none;
    font-weight: 500;
}

/* Loader */
.loader {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
    padding: 32px;
    color: var(--text-muted);
    font-weight: 500;
}
.spinner {
    width: 36px;
    height: 36px;
    border: 3px solid var(--spinner-track);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}
@keyframes spin {
    to { transform: rotate(360deg); }
}

/* History */
.history-list {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    flex-direction: column;
    gap: 12px;
}
.history-item {
    background: var(--surface-alt);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 16px 18px;
}
.history-meta {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 600;
    margin-bottom: 8px;
}
.history-body {
    color: var(--text-main);
    line-height: 1.6;
}

/* Focus ring for keyboard users */
button:focus-visible,
select:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* Responsive */
@media (max-width: 640px) {
    .top-header { padding: 40px 0 32px; }
    .top-header h1 { font-size: 1.5rem; }
    .nav-wrapper {
        flex-direction: column;
        height: auto;
        gap: 12px;
        padding: 12px 0;
    }
    .tabs-group { flex-wrap: wrap; justify-content: center; }
    .tab-btn { padding: 14px 12px; }
    .card { padding: 20px; }
    .control-row { flex-direction: column; align-items: stretch; }
    .btn-primary { width: 100%; }
}
/* Progress Tab Layout */
.stats-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 24px;
}

.stat-card {
    padding: 24px;
    border-radius: 16px;
    color: #ffffff;
    box-shadow: var(--shadow-md);
}

.blue-grad { background: linear-gradient(135deg, #3b82f6, #2563eb); }
.orange-grad { background: linear-gradient(135deg, #f97316, #ea580c); }

.stat-value { font-size: 2.8rem; font-weight: 800; margin: 4px 0; }
.stat-label { font-size: 0.75rem; font-weight: 700; opacity: 0.9; letter-spacing: 1px; }

/* Chart Styling */
.chart-container {
    height: 250px;
    display: flex;
    align-items: flex-end;
    justify-content: space-around;
    padding: 20px;
    border-bottom: 2px solid var(--border);
}

.bar-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 60px;
}

.bar {
    width: 35px;
    background: var(--primary);
    border-radius: 6px 6px 0 0;
    transition: height 0.8s cubic-bezier(0.4, 0, 0.2, 1);
    min-height: 4px; /* So 0 still shows a tiny line */
}

.bar-label {
    font-size: 0.75rem;
    margin-top: 12px;
    font-weight: 600;
    color: var(--text-muted);
}

.goal-card {
    background: var(--goal-bg);
    border: 1px solid var(--goal-border);
    padding: 16px;
    border-radius: 12px;
    text-align: center;
    color: var(--goal-text);
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* =========================================
   Authentication Overlay & Modal
   ========================================= */
.auth-overlay{
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.6);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    opacity: 0; /* Hidden by default*/
    pointer-events: none;
    transition: opacity 0.3s ease;

}

.auth-overlay.active {
    opacity: 1;
    pointer-events: auto;
}
.auth-card{
    position: relative;
    background: var(--surface);
    padding: 2.5rem 2rem;
    border-radius: 16px;
    width: 100%;
    max-width: 400px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border);
    transform: translateY(8px) scale(0.98);
    opacity: 0;
    transition: transform 0.25s ease, opacity 0.25s ease;
}
.auth-overlay.active .auth-card{
    transform: translateY(0) scale(1);
    opacity: 1;
}
.auth-close{
    position: absolute;
    top: 12px;
    right:12px;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 1.5rem;
    line-height: 1;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.15s ease, color 0.15s ease;
}
.auth-close:hover{
    background: var(--surface-alt);
    color: var(--text-main);
}
.auth-card h2{
    margin: 0 0 0.5rem 0;
    color: var(--text-main);
    text-align: center;
    font-size: 1.5rem;
}
.auth-card p{
    margin: 0 0 0.5rem 0;
    color: var(--text-main);
    text-align: center;
    font-size: 0.9rem;
}
.form-group{
    margin-bottom: 1rem;
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 8px;
}
.form-group label{
    font-size: 0.85rem;
    font-weight: 600;
    color:var(--text-muted);
}
.form-group input{
    width: 100%;
    padding: 0.75rem;
    background-color: var(--surface);
    color: var(--text-main);
    border: 1px solid var(--border);
    border-radius: 8px;
    box-sizing: border-box;
    font-size: 1rem;
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.form-group input:focus{
    outline:none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-soft);
}
.password-field{
    position: relative;
    display: flex;
    align-items: center;
}
.password-field input{
    padding-right: 2.75rem;
}
.password-field input::-ms-reveal,
.password-field input::-ms-clear{
    display: none;
}
.toggle-password {
    position: absolute;
    right: 0.5rem;
    top: 50%;
    transform: translateY(-50%);
    background: transparent;
    border: none;
    padding: 4px 8px;
    font-size: 1rem;
    line-height: 1;
    cursor: pointer;
    color: var(--text-muted);
    border-radius: 6px;
    transition: background-color 0.15s ease;
}
.toggle-password:hover{
    background: var(--surface-alt);
}
.form-error{
    color: #dc2626;
    font-size: 0.85rem;
    margin: -0.25rem 0 0.75rem;
    min-height: 1.1rem;
    display: none;
}
.font-error.visible{
    display: block;
}
[data-theme="dark"].font-error{
    color:#f87171;
}
.auth-submit-btn{
    width: 100px;
    padding:12px 24px;
    background: var(--primary);
    color: #ffffff;
    border: none;
    font-weight: 600;
    border-radius: 8px;
    font-size: 0.95rem;
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    transition: background-color 0.15s ease, transform 0.15s ease, box-shadow 0.15s ease;
}
.auth-submit-btn:hover{
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}
.auth-submit-btn:active {
    transform: scale(0.98); 
}
.google-btn{
    width: 100%;
    padding: 0.75rem;
    background-color: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    color: var(--text-main);
    transition: background-color 0.15s ease;
}
.google-btn:hover {
    background-color: var(--surface-alt);
}
.link-btn{
    background: none;
    border: none;
    color: var(--primary);
    font-weight: 600;
    cursor: pointer;
    padding: 0;
    font-size: 0.875rem;
}
.link-btn:hover{
    text-decoration: underline;
}
.forgot{
    text-align: right;
    margin-bottom: 1.5rem;
}
.forgot-link{
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--primary);
    text-decoration: none;
}
.forgot-link:hover{
    text-decoration: underline;
}
.auth-divider{
    display: flex;
    align-items: center;
    margin: 1.5rem 0;
    color: var(--text-muted);
    font-size: 0.875rem;
}
.auth-divider::before,
.auth-divider::after {
    content: "";
    flex: 1;
    border-bottom: 1px solid var(--border);
}
.auth-divider span{
    padding: 0 0.75rem;

}
.auth-toggle{
    margin-top: 1.5rem;
    text-align: center;
    font-size: 0.875rem;
    color: var(--text-muted);
}
.hidden{
    display: none !important;
}

/* Floating "Explain" button */
.explain-selection-btn {
    position: absolute;
    z-index: 50;
    background: var(--primary);
    color: #ffffff;
    border: none;
    border-radius: 999px;
    padding: 6px 12px;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    box-shadow: var(--shadow-md);
    transition: transform 0.12s ease, background-color 0.15s ease;
}
.explain-selection-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
}
.explain-selection-btn[hidden] { display: none; }

/* Side chat panel */
.chat-panel {
    position: fixed;
    top: 0;
    right: 0;
    height: 100vh;
    width: 380px;
    max-width: 90vw;
    background: var(--surface);
    border-left: 1px solid var(--border);
    box-shadow: var(--shadow-lg);
    display: flex;
    flex-direction: column;
    transform: translateX(100%);
    transition: transform 0.25s ease;
    z-index: 200;
}
.chat-panel.open {
    transform: translateX(0);
}
.chat-panel-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    padding: 18px 20px;
    border-bottom: 1px solid var(--border);
    background: var(--header-gradient);
    color: #ffffff;
}
.chat-panel-header h3 {
    margin: 0;
    font-size: 1.05rem;
    font-weight: 700;
}
.chat-panel-header p {
    margin: 4px 0 0;
    font-size: 0.82rem;
    opacity: 0.9;
}
.chat-panel-close {
    background: rgba(255, 255, 255, 0.15);
    color: #ffffff;
    border: none;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    font-size: 1.4rem;
    line-height: 1;
    cursor: pointer;
    transition: background-color 0.15s ease;
}
.chat-panel-close:hover { background: rgba(255, 255, 255, 0.3); }

.chat-messages {
    flex: 1;
    overflow-y: auto;
    padding: 16px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}
.chat-empty {
    color: var(--text-muted);
    font-size: 0.9rem;
    text-align: center;
    padding: 24px 12px;
}
.chat-msg {
    max-width: 88%;
    padding: 10px 14px;
    border-radius: 14px;
    font-size: 0.95rem;
    line-height: 1.55;
    overflow-wrap: anywhere;
    word-break: break-word;
}
.chat-msg.user {
    align-self: flex-end;
    background: var(--primary);
    color: #ffffff;
    border-bottom-right-radius: 4px;
}
.chat-msg.assistant {
    align-self: flex-start;
    background: var(--surface-alt);
    color: var(--text-main);
    border: 1px solid var(--border);
    border-bottom-left-radius: 4px;
}
.chat-msg .chat-selection-tag {
    display: block;
    font-size: 0.75rem;
    opacity: 0.8;
    margin-bottom: 4px;
    font-style: italic;
}
.chat-msg.loading {
    color: var(--text-muted);
    font-style: italic;
}

.chat-form {
    display: flex;
    gap: 8px;
    padding: 12px;
    border-top: 1px solid var(--border);
    background: var(--surface);
}
.chat-form textarea {
    flex: 1;
    resize: none;
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 10px 12px;
    font-family: inherit;
    font-size: 0.95rem;
    background: var(--surface-alt);
    color: var(--text-main);
}
.chat-form textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-soft);
}
.chat-send-btn {
    background: var(--primary);
    color: #ffffff;
    border: none;
    border-radius: 10px;
    padding: 0 16px;
    cursor: pointer;
    font-size: 1.1rem;
    transition: background-color 0.15s ease;
}
.chat-send-btn:hover { background: var(--primary-hover); }
.chat-send-btn:disabled {
    background: var(--text-muted);
    cursor: not-allowed;
}