/* LitFinder: shared design system and page styles */

:root {
    --bg: #f6f7fb;
    --surface: #ffffff;
    --surface-2: #f1f3f9;
    --border: #e3e6ef;
    --text: #151a2d;
    --text-2: #4a5170;
    --text-3: #7a819c;
    --primary: #3d5afe;
    --primary-hover: #2f49e0;
    --primary-soft: #eef1ff;
    --accent: #0f9d76;
    --accent-soft: #e6f6f1;
    --warn: #b7791f;
    --warn-soft: #fdf5e6;
    --danger: #d64545;
    --danger-soft: #fdeeee;
    --shadow-sm: 0 1px 2px rgba(20, 26, 50, 0.06);
    --shadow: 0 4px 16px rgba(20, 26, 50, 0.08);
    --radius: 14px;
    --radius-sm: 9px;
    --font: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
    --mono: ui-monospace, SFMono-Regular, Menlo, monospace;
    color-scheme: light;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #0f1220;
        --surface: #171b2e;
        --surface-2: #1f2439;
        --border: #2b3150;
        --text: #e8eaf5;
        --text-2: #b4b9d1;
        --text-3: #858ba8;
        --primary: #7b8fff;
        --primary-hover: #95a5ff;
        --primary-soft: #232a4f;
        --accent: #3ccf9f;
        --accent-soft: #173a31;
        --warn: #e8b04a;
        --warn-soft: #3a2f17;
        --danger: #f07b7b;
        --danger-soft: #3e1f25;
        --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
        --shadow: 0 4px 18px rgba(0, 0, 0, 0.35);
        color-scheme: dark;
    }
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
    margin: 0;
    font-family: var(--font);
    font-size: 15px;
    line-height: 1.6;
    color: var(--text);
    background: var(--bg);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

main { flex: 1; }

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

h1, h2, h3, h4 { line-height: 1.25; margin: 0 0 0.5em; }

.container { width: 100%; max-width: 1080px; margin: 0 auto; padding: 0 20px; }
.container.narrow { max-width: 820px; }

.sr-only {
    position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
    overflow: hidden; clip: rect(0, 0, 0, 0); border: 0;
}

:focus-visible { outline: 2px solid var(--primary); outline-offset: 2px; border-radius: 4px; }

/* ---------------------------------------------------------------- header */

.site-header {
    position: sticky;
    top: 0;
    z-index: 20;
    background: color-mix(in srgb, var(--surface) 88%, transparent);
    backdrop-filter: saturate(160%) blur(10px);
    border-bottom: 1px solid var(--border);
}

.site-header .container { display: flex; align-items: center; justify-content: space-between; height: 60px; }

.brand { display: flex; align-items: center; gap: 10px; color: var(--text); font-weight: 700; font-size: 18px; }
.brand:hover { text-decoration: none; }
.brand-mark {
    width: 32px; height: 32px; border-radius: 9px;
    display: grid; place-items: center;
    background: linear-gradient(135deg, var(--primary), #8a5cf6);
    color: #fff; font-size: 15px;
}

.site-nav { display: flex; gap: 4px; }
.site-nav a {
    color: var(--text-2); font-weight: 500; font-size: 14px;
    padding: 7px 12px; border-radius: 8px;
}
.site-nav a:hover { background: var(--surface-2); color: var(--text); text-decoration: none; }
.site-nav a.active { color: var(--primary); background: var(--primary-soft); }
.nav-count {
    display: inline-block; min-width: 18px; padding: 0 5px; margin-left: 4px;
    border-radius: 9px; background: var(--primary); color: #fff;
    font-size: 11px; line-height: 18px; text-align: center;
}
.nav-count:empty { display: none; }

.site-footer { border-top: 1px solid var(--border); padding: 22px 0; margin-top: 48px; color: var(--text-3); font-size: 13px; }
.site-footer .container { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.site-footer a { color: var(--text-2); }

/* --------------------------------------------------------------- buttons */

.btn {
    display: inline-flex; align-items: center; justify-content: center; gap: 8px;
    font: inherit; font-weight: 600; font-size: 14px;
    padding: 9px 16px; border-radius: var(--radius-sm);
    border: 1px solid transparent; cursor: pointer;
    transition: background 0.15s, border-color 0.15s, color 0.15s, transform 0.05s;
    white-space: nowrap;
}
.btn:hover { text-decoration: none; }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: 0.55; cursor: not-allowed; }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover:not(:disabled) { background: var(--primary-hover); }
.btn-ghost { background: transparent; color: var(--text-2); border-color: var(--border); }
.btn-ghost:hover:not(:disabled) { background: var(--surface-2); color: var(--text); }
.btn-sm { padding: 6px 11px; font-size: 13px; }
.btn-lg { padding: 12px 22px; font-size: 15px; }
.btn-icon { padding: 7px; width: 34px; height: 34px; }

/* ------------------------------------------------------------------ chips */

.chip {
    display: inline-flex; align-items: center; gap: 6px;
    padding: 5px 11px; border-radius: 999px;
    background: var(--surface-2); color: var(--text-2);
    border: 1px solid var(--border);
    font: inherit; font-size: 13px; cursor: pointer;
    transition: background 0.15s, color 0.15s, border-color 0.15s;
}
.chip:hover { border-color: var(--primary); color: var(--primary); }
.chip-static { cursor: default; }
.chip-static:hover { border-color: var(--border); color: var(--text-2); }
.chip .fa-xmark { font-size: 11px; opacity: 0.6; }

.badge {
    display: inline-flex; align-items: center; gap: 5px;
    padding: 2px 9px; border-radius: 999px;
    font-size: 12px; font-weight: 600;
    background: var(--surface-2); color: var(--text-2);
}
.badge-oa { background: var(--accent-soft); color: var(--accent); }
.badge-type { background: var(--primary-soft); color: var(--primary); }

/* ----------------------------------------------------------------- forms */

.field-label { display: block; font-size: 13px; font-weight: 600; color: var(--text-2); margin-bottom: 6px; }

.input, select.input {
    width: 100%; font: inherit; font-size: 14px; color: var(--text);
    background: var(--surface); border: 1px solid var(--border);
    border-radius: var(--radius-sm); padding: 8px 11px;
    transition: border-color 0.15s, box-shadow 0.15s;
}
.input:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-soft); }

.check { display: inline-flex; align-items: center; gap: 8px; font-size: 14px; color: var(--text-2); cursor: pointer; }
.check input { width: 16px; height: 16px; accent-color: var(--primary); }

/* Search box shared by home and results pages */
.search-box {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 14px;
    transition: border-color 0.15s, box-shadow 0.15s;
}
.search-box:focus-within { border-color: var(--primary); box-shadow: 0 0 0 4px var(--primary-soft), var(--shadow); }

.search-box textarea {
    width: 100%; border: 0; resize: none; background: transparent;
    font: inherit; font-size: 17px; line-height: 1.5; color: var(--text);
    padding: 4px 6px; min-height: 30px; max-height: 220px;
}
.search-box textarea:focus { outline: none; }
.search-box textarea::placeholder { color: var(--text-3); }

.search-box-bar {
    display: flex; align-items: center; justify-content: space-between; gap: 10px;
    margin-top: 10px; flex-wrap: wrap;
}
.search-box-left { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }

.segmented {
    display: inline-flex; padding: 3px; gap: 2px;
    background: var(--surface-2); border-radius: 10px; border: 1px solid var(--border);
}
.segmented button {
    font: inherit; font-size: 13px; font-weight: 600;
    border: 0; background: transparent; color: var(--text-2);
    padding: 5px 12px; border-radius: 7px; cursor: pointer;
    display: inline-flex; align-items: center; gap: 6px;
}
.segmented button[aria-pressed="true"] { background: var(--surface); color: var(--text); box-shadow: var(--shadow-sm); }

.kbd-hint { color: var(--text-3); font-size: 12px; }
.kbd-hint kbd {
    font-family: var(--mono); font-size: 11px;
    padding: 1px 5px; border-radius: 4px;
    border: 1px solid var(--border); background: var(--surface-2);
}

.mode-help { font-size: 13px; color: var(--text-3); margin: 10px 4px 0; }

.filters-panel {
    display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 14px;
    border-top: 1px dashed var(--border); margin-top: 12px; padding-top: 14px;
}
.filters-panel[hidden] { display: none; }
.filters-panel .check { align-self: end; padding-bottom: 8px; }
.filters-note { grid-column: 1 / -1; font-size: 12px; color: var(--text-3); margin: -4px 0 0; }

.form-error {
    display: flex; gap: 10px; align-items: flex-start;
    margin-top: 12px; padding: 10px 14px; border-radius: var(--radius-sm);
    background: var(--danger-soft); color: var(--danger); font-size: 14px;
}
.form-error[hidden] { display: none; }

/* ------------------------------------------------------------------ home */

.hero { padding: 64px 0 28px; text-align: center; }
.hero h1 { font-size: clamp(30px, 5vw, 44px); letter-spacing: -0.02em; margin-bottom: 12px; }
.hero h1 .grad {
    background: linear-gradient(90deg, var(--primary), #8a5cf6);
    -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero p { color: var(--text-2); font-size: 17px; max-width: 640px; margin: 0 auto; }

.home-search { margin-top: 8px; }

.suggestions { margin-top: 18px; }
.suggestions h2 { font-size: 13px; font-weight: 600; color: var(--text-3); text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 10px; }
.chip-row { display: flex; flex-wrap: wrap; gap: 8px; }

.how { padding: 48px 0 8px; }
.how h2 { text-align: center; font-size: 24px; margin-bottom: 24px; }
.how-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.how-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; }
.how-card .step {
    width: 34px; height: 34px; border-radius: 10px; display: grid; place-items: center;
    background: var(--primary-soft); color: var(--primary); font-weight: 700; margin-bottom: 12px;
}
.how-card h3 { font-size: 16px; }
.how-card p { color: var(--text-2); font-size: 14px; margin: 0; }
.how-agent {
    margin-top: 16px; display: flex; gap: 14px; align-items: flex-start;
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px 20px;
}
.how-agent i { color: #8a5cf6; font-size: 20px; margin-top: 3px; }
.how-agent p { margin: 0; color: var(--text-2); font-size: 14px; }

/* --------------------------------------------------------------- results */

.results-top { padding: 22px 0 6px; }

.results-meta {
    display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap;
    margin: 18px 0 12px;
}
.results-meta .count { font-weight: 600; }
.results-meta .muted { color: var(--text-3); font-weight: 400; }
.toolbar { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.toolbar select.input { width: auto; padding: 6px 10px; font-size: 13px; }

.query-plan {
    display: flex; align-items: center; gap: 8px; flex-wrap: wrap;
    font-size: 13px; color: var(--text-3); margin-top: 12px;
}
.query-plan .chip { font-size: 12px; padding: 3px 10px; }

.refine-panel {
    display: flex; gap: 16px; align-items: flex-end; flex-wrap: wrap;
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
    padding: 14px 16px; margin-bottom: 14px;
}
.refine-panel[hidden] { display: none; }
.refine-panel .field { min-width: 110px; }
.refine-panel .input { width: 110px; }

.results-layout { display: grid; grid-template-columns: minmax(0, 1fr); gap: 18px; }
.results-layout.with-side { grid-template-columns: minmax(0, 1fr) 300px; }

.paper-list { display: flex; flex-direction: column; gap: 12px; }

.paper {
    position: relative;
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
    padding: 18px 20px 16px 58px;
    transition: border-color 0.15s, box-shadow 0.15s;
}
.paper.no-rank { padding-left: 20px; }
.paper:hover { border-color: color-mix(in srgb, var(--primary) 35%, var(--border)); box-shadow: var(--shadow-sm); }

.paper-rank {
    position: absolute; left: 18px; top: 19px;
    width: 26px; height: 26px; border-radius: 8px;
    display: grid; place-items: center;
    background: var(--surface-2); color: var(--text-3);
    font-size: 12px; font-weight: 700;
}

.paper-title { font-family: var(--serif); font-size: 19px; font-weight: 600; line-height: 1.35; margin: 0 40px 4px 0; }
.paper-title a { color: var(--text); }
.paper-title a:hover { color: var(--primary); text-decoration: none; }

.paper-byline { color: var(--text-2); font-size: 14px; margin-bottom: 8px; }
.paper-byline .venue { font-style: italic; }
.dot::before { content: "·"; margin: 0 7px; color: var(--text-3); }

.paper-badges { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 10px; }

.paper-abstract { color: var(--text-2); font-size: 14px; margin: 0; }
.paper-abstract.clamped {
    display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden;
}
.paper-abstract.missing { color: var(--text-3); font-style: italic; }
.link-btn {
    font: inherit; font-size: 13px; font-weight: 600; color: var(--primary);
    background: none; border: 0; padding: 0; cursor: pointer;
}
.link-btn:hover { text-decoration: underline; }

.paper-reason {
    margin-top: 12px; padding: 10px 12px; border-radius: var(--radius-sm);
    background: color-mix(in srgb, #8a5cf6 10%, var(--surface)); color: var(--text-2); font-size: 14px;
    border-left: 3px solid #8a5cf6;
}
.paper-reason strong { color: var(--text); }

.paper-actions { display: flex; gap: 6px; flex-wrap: wrap; margin-top: 12px; }

.save-toggle {
    position: absolute; right: 14px; top: 14px;
    background: none; border: 0; cursor: pointer; font-size: 17px;
    color: var(--text-3); width: 34px; height: 34px; border-radius: 8px;
}
.save-toggle:hover { background: var(--surface-2); color: var(--primary); }
.save-toggle[aria-pressed="true"] { color: var(--primary); }

/* Agent panels */
.agent-card {
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
    padding: 18px 20px; margin-bottom: 14px;
}
.agent-card h2 { font-size: 15px; display: flex; align-items: center; gap: 8px; }
.agent-card h2 i { color: #8a5cf6; }
.agent-summary { color: var(--text); font-size: 15px; margin: 0; }
.agent-stats { display: flex; gap: 14px; flex-wrap: wrap; color: var(--text-3); font-size: 12px; margin-top: 12px; }

.trace { margin-top: 12px; }
.trace summary { cursor: pointer; font-size: 13px; font-weight: 600; color: var(--text-2); }
.trace ol { margin: 10px 0 0; padding-left: 0; list-style: none; display: flex; flex-direction: column; gap: 6px; }
.trace li {
    display: grid; grid-template-columns: 54px 1fr; gap: 8px;
    font-size: 12px; padding: 7px 10px; border-radius: 8px; background: var(--surface-2);
}
.trace li.error { background: var(--danger-soft); }
.trace .step-no { color: var(--text-3); font-weight: 600; }
.trace code { font-family: var(--mono); font-size: 12px; color: var(--text); word-break: break-word; }
.trace .result { color: var(--text-3); display: block; }

.side-card {
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
    padding: 16px 18px; position: sticky; top: 76px;
}
.side-card h2 { font-size: 14px; display: flex; gap: 8px; align-items: center; }
.person { padding: 10px 0; border-top: 1px solid var(--border); }
.person:first-of-type { border-top: 0; padding-top: 2px; }
.person-name { font-weight: 600; }
.person-meta { font-size: 12px; color: var(--text-3); }
.person-reason { font-size: 13px; color: var(--text-2); margin-top: 4px; }

/* Loading state */
.loading-card {
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
    padding: 22px; display: flex; gap: 18px; align-items: flex-start; margin-bottom: 14px;
}
.spinner {
    width: 26px; height: 26px; flex: none; border-radius: 50%;
    border: 3px solid var(--primary-soft); border-top-color: var(--primary);
    animation: spin 0.9s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.loading-text h2 { font-size: 16px; margin-bottom: 4px; }
.loading-text p { margin: 0; color: var(--text-3); font-size: 14px; }
.loading-steps { list-style: none; padding: 0; margin: 12px 0 0; display: flex; flex-direction: column; gap: 6px; font-size: 14px; }
.loading-steps li { color: var(--text-3); display: flex; gap: 8px; align-items: center; }
.loading-steps li.active { color: var(--text); font-weight: 600; }
.loading-steps li.done { color: var(--accent); }
.loading-steps i { width: 16px; text-align: center; }

.skeleton { border-radius: var(--radius); border: 1px solid var(--border); background: var(--surface); padding: 20px; }
.skeleton .bar {
    height: 12px; border-radius: 6px; margin-bottom: 10px;
    background: linear-gradient(90deg, var(--surface-2), var(--border), var(--surface-2));
    background-size: 200% 100%; animation: shimmer 1.4s ease-in-out infinite;
}
@keyframes shimmer { to { background-position: -200% 0; } }

/* Empty / error states */
.state {
    text-align: center; padding: 48px 24px; background: var(--surface);
    border: 1px dashed var(--border); border-radius: var(--radius);
}
.state i.big { font-size: 34px; color: var(--text-3); margin-bottom: 12px; }
.state h2 { font-size: 18px; }
.state p { color: var(--text-2); max-width: 520px; margin: 0 auto 16px; }
.state.error i.big { color: var(--danger); }

/* ----------------------------------------------------------- publication */

.back-link { display: inline-flex; gap: 8px; align-items: center; font-size: 14px; margin: 22px 0 14px; color: var(--text-2); }

.pub-header { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 26px 28px; }
.pub-header h1 { font-family: var(--serif); font-size: clamp(22px, 3.2vw, 30px); font-weight: 600; margin-bottom: 10px; }
.pub-authors { color: var(--text-2); margin-bottom: 4px; }
.pub-venue { color: var(--text-3); font-size: 14px; }
.pub-stats { display: flex; gap: 26px; flex-wrap: wrap; margin: 18px 0; }
.stat .value { font-size: 20px; font-weight: 700; }
.stat .label { font-size: 12px; color: var(--text-3); text-transform: uppercase; letter-spacing: 0.05em; }

.pub-grid { display: grid; grid-template-columns: minmax(0, 1fr) 300px; gap: 18px; margin-top: 18px; }
.panel { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px 24px; margin-bottom: 18px; }
.panel h2 { font-size: 16px; }
.pub-abstract { font-size: 15.5px; line-height: 1.75; color: var(--text); margin: 0; }
.topic-list { display: flex; flex-wrap: wrap; gap: 6px; }

.analysis-grid { display: grid; gap: 14px; }
.analysis-grid h3 { font-size: 13px; text-transform: uppercase; letter-spacing: 0.05em; color: var(--text-3); margin-bottom: 4px; }
.analysis-grid ul { margin: 0; padding-left: 18px; color: var(--text-2); }
.analysis-grid p { margin: 0; color: var(--text-2); }
.note { font-size: 12px; color: var(--text-3); }

.related-list { list-style: none; margin: 0; padding: 0; }
.related-list li { padding: 10px 0; border-top: 1px solid var(--border); font-size: 14px; }
.related-list li:first-child { border-top: 0; padding-top: 0; }
.related-list .meta { font-size: 12px; color: var(--text-3); }

/* ----------------------------------------------------------------- toast */

.toast {
    position: fixed; left: 50%; bottom: 24px; transform: translate(-50%, 20px);
    background: var(--text); color: var(--bg);
    padding: 10px 16px; border-radius: 10px; font-size: 14px; box-shadow: var(--shadow);
    opacity: 0; pointer-events: none; transition: opacity 0.2s, transform 0.2s; z-index: 50;
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }

.page-title { padding: 30px 0 6px; }
.page-title h1 { font-size: 28px; margin-bottom: 4px; }
.page-title p { color: var(--text-2); margin: 0; }

/* ------------------------------------------------------------ responsive */

@media (max-width: 900px) {
    .results-layout.with-side, .pub-grid { grid-template-columns: minmax(0, 1fr); }
    .side-card { position: static; }
    .how-grid { grid-template-columns: 1fr; }
    .filters-panel { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 560px) {
    body { font-size: 14px; }
    .container { padding: 0 16px; }
    .site-nav a span.label { display: none; }
    .hero { padding: 40px 0 20px; }
    .search-box textarea { font-size: 16px; }
    .kbd-hint { display: none; }
    .query-plan { flex-wrap: nowrap; overflow-x: auto; padding-bottom: 4px; }
    .query-plan > * { flex: none; }
    .paper, .paper.no-rank { padding: 16px 16px 14px 16px; }
    .paper-rank { position: static; margin-bottom: 8px; }
    .paper-title { font-size: 17px; }
    .filters-panel { grid-template-columns: 1fr; }
    .pub-header { padding: 20px; }
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after { animation: none !important; transition: none !important; }
}