/* Lá Chắn Số Học Đường — giao diện.
   Bảng màu: giấy vở ô li xanh nhạt, mực xanh đồng phục. Đỏ CHỈ dùng cho mức "nguy hiểm". */
:root {
  --paper: #f5f8fc;
  --sheet: #ffffff;
  --ink: #1b2942;
  --ink-soft: #4a5872;
  --rule: #d4dcea;
  --grid: #e8eef7;
  --blue: #1f4fbf;
  --blue-soft: #e4ecfb;
  --safe: #2c7a4b;
  --safe-bg: #e6f3eb;
  --caution: #a8650c;
  --caution-bg: #fdf1dc;
  --danger: #b8322a;
  --danger-bg: #fbe7e5;
  --mark: #fff0b3;
  --radius-lg: 14px;
  --radius-sm: 6px;
  --font: "Segoe UI", "Noto Sans", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: "Cascadia Mono", Consolas, "DejaVu Sans Mono", monospace;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.55;
  color: var(--ink);
  background-color: var(--paper);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 24px 24px;
}

a { color: var(--blue); }
:focus-visible { outline: 3px solid var(--blue); outline-offset: 2px; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
[hidden] { display: none !important; }

/* ---------- đầu trang ---------- */
.top { background: var(--ink); color: #fff; padding: 14px 20px; }
.top-inner { max-width: 1180px; margin: 0 auto; display: flex; flex-wrap: wrap; gap: 8px 20px; align-items: baseline; justify-content: space-between; }
.brand { font-size: 1.35rem; font-weight: 700; letter-spacing: -0.01em; margin: 0; }
.brand small { display: block; font-size: 0.8rem; font-weight: 400; opacity: 0.75; }
.top nav { display: inline; }
.top nav a { color: #cfe0ff; margin-left: 14px; font-size: 0.9rem; }
.mode-badge { font-size: 0.8rem; border: 1px solid #5d6f92; border-radius: 99px; padding: 2px 10px; }

.privacy {
  max-width: 1148px; margin: 14px auto 0; padding: 10px 16px;
  background: var(--blue-soft); border-left: 4px solid var(--blue); border-radius: var(--radius-sm);
  font-size: 0.92rem;
}
@media (max-width: 1180px) { .privacy { margin: 14px 16px 0; } }

/* ---------- bố cục ---------- */
.layout { max-width: 1180px; margin: 16px auto 40px; padding: 0 16px; display: grid; gap: 18px; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); align-items: start; }
@media (max-width: 860px) { .layout { grid-template-columns: 1fr; } }

.card { background: var(--sheet); border: 1px solid var(--rule); border-radius: var(--radius-lg); padding: 18px; }
.card h2 { font-size: 1.1rem; margin: 0 0 12px; }

/* ---------- tab ---------- */
.tabs { display: flex; gap: 4px; border-bottom: 2px solid var(--rule); margin-bottom: 14px; overflow-x: auto; }
.tab {
  appearance: none; border: 0; background: none; font: inherit; color: var(--ink-soft); white-space: nowrap;
  padding: 9px 14px; cursor: pointer; border-bottom: 3px solid transparent; margin-bottom: -2px;
}
.tab[aria-selected="true"] { color: var(--blue); border-bottom-color: var(--blue); font-weight: 600; }
.tab-count { font-size: 0.75rem; background: var(--blue); color: #fff; border-radius: 99px; padding: 0 6px; margin-left: 4px; }

label { display: block; font-weight: 600; margin: 10px 0 4px; font-size: 0.95rem; }
.hint { color: var(--ink-soft); font-size: 0.85rem; margin: 4px 0 0; }
textarea, input[type="text"], input[type="url"], input[type="password"], input[type="date"], select {
  width: 100%; font: inherit; color: var(--ink); background: #fff;
  border: 1px solid var(--rule); border-radius: var(--radius-sm); padding: 9px 10px;
}
textarea { min-height: 140px; resize: vertical; }
textarea.small { min-height: 80px; }

.file-row { display: flex; flex-wrap: wrap; gap: 8px; }
.file-btn { position: relative; overflow: hidden; }
.file-btn input { position: absolute; inset: 0; opacity: 0; cursor: pointer; }

.preview { margin-top: 12px; border: 1px dashed var(--rule); border-radius: var(--radius-sm); padding: 8px; text-align: center; background: var(--paper); }
.preview img { max-width: 100%; max-height: 280px; border-radius: 4px; }

.progress { height: 6px; background: var(--grid); border-radius: 99px; overflow: hidden; margin-top: 8px; }
.progress > span { display: block; height: 100%; width: 0; background: var(--blue); transition: width .2s; }
.ocr-quality { margin: 6px 0; padding: 7px 9px; border-radius: var(--radius-sm); background: var(--blue-soft); color: var(--ink-soft); font-size: .85rem; }

/* ---------- nút ---------- */
.btn {
  appearance: none; font: inherit; cursor: pointer; border-radius: var(--radius-sm);
  border: 1px solid var(--rule); background: #fff; color: var(--ink); padding: 8px 14px; display: inline-block;
}
.btn:hover { border-color: var(--blue); }
.btn-primary { background: var(--blue); border-color: var(--blue); color: #fff; font-weight: 600; padding: 11px 22px; }
.btn-primary:hover { background: #193f99; }
.btn-danger-outline { color: var(--danger); }
.btn:disabled { opacity: .55; cursor: not-allowed; }
.actions { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin-top: 16px; }
.actions select { width: auto; max-width: 100%; }

fieldset.versions { border: 1px solid var(--rule); border-radius: var(--radius-sm); margin: 14px 0 0; padding: 8px 12px; }
fieldset.versions legend { font-weight: 600; font-size: 0.95rem; padding: 0 4px; }
.versions label { display: inline-flex; gap: 6px; align-items: center; font-weight: 400; margin: 2px 14px 2px 0; }

.status { margin-top: 10px; min-height: 1.4em; font-size: 0.92rem; color: var(--ink-soft); }
.status.error { color: var(--danger); }

/* ---------- kết quả ---------- */
.empty { color: var(--ink-soft); text-align: center; padding: 30px 10px; }
.gauge-wrap { display: flex; gap: 18px; align-items: center; flex-wrap: wrap; }
.gauge { width: 210px; height: auto; flex: none; }
.gauge .track { fill: none; stroke: var(--grid); stroke-width: 18; stroke-linecap: round; }
.gauge .value { fill: none; stroke: var(--safe); stroke-width: 18; stroke-linecap: round; transition: stroke-dasharray .6s ease; }
.gauge .num { font: 700 44px var(--font); fill: var(--ink); }
.gauge .unit { font: 13px var(--font); fill: var(--ink-soft); }
.level-caution .gauge .value { stroke: var(--caution); }
.level-dangerous .gauge .value { stroke: var(--danger); }
@media (prefers-reduced-motion: reduce) { .gauge .value, .progress > span { transition: none; } }

.verdict { font-size: 1.25rem; font-weight: 700; margin: 0; }
.level-safe .verdict { color: var(--safe); }
.level-caution .verdict { color: var(--caution); }
.level-dangerous .verdict { color: var(--danger); }
.meta { font-size: 0.82rem; color: var(--ink-soft); margin-top: 4px; }

.explain { margin: 14px 0; padding: 12px 14px; border-radius: var(--radius-sm); background: var(--safe-bg); }
.level-caution .explain { background: var(--caution-bg); }
.level-dangerous .explain { background: var(--danger-bg); }

h3 { font-size: 1rem; margin: 18px 0 8px; }
.signals { list-style: none; padding: 0; margin: 0; display: grid; gap: 8px; }
.signal { border: 1px solid var(--rule); border-radius: var(--radius-sm); padding: 10px 12px; }
.signal-head { display: flex; justify-content: space-between; gap: 10px; align-items: baseline; }
.signal-title { font-weight: 600; }
.signal-weight { font-size: 0.8rem; color: var(--ink-soft); white-space: nowrap; }
.signal-cat { font-size: 0.82rem; color: var(--blue); }
.signal p { margin: 4px 0 0; font-size: 0.92rem; }
.evidence { font-family: var(--mono); font-size: 0.82rem; background: var(--paper); padding: 1px 6px; border-radius: 4px; margin-right: 4px; word-break: break-all; }

.highlighted { white-space: pre-wrap; word-break: break-word; border: 1px solid var(--rule); border-radius: var(--radius-sm); padding: 10px 12px; background: #fff; max-height: 320px; overflow: auto; }
.highlighted mark { background: var(--mark); border-bottom: 2px solid var(--caution); padding: 0 1px; color: inherit; }
.level-dangerous .highlighted mark { border-bottom-color: var(--danger); }

.urls { list-style: none; padding: 0; margin: 0; font-size: 0.9rem; }
.urls li { padding: 6px 0; border-bottom: 1px solid var(--grid); word-break: break-all; }
.urls code { font-family: var(--mono); }
.tag { display: inline-block; font-size: 0.75rem; border: 1px solid var(--rule); border-radius: 99px; padding: 0 8px; margin: 2px 4px 0 0; }
.tag.ok { border-color: var(--safe); color: var(--safe); }

ol.todo { padding-left: 20px; margin: 0; }
ol.todo li { margin: 4px 0; }
.disclaimer { font-size: 0.82rem; color: var(--ink-soft); border-top: 1px solid var(--rule); margin-top: 16px; padding-top: 10px; }

table.compare { width: 100%; border-collapse: collapse; font-size: 0.92rem; }
table.compare th, table.compare td { border: 1px solid var(--rule); padding: 6px 8px; text-align: left; vertical-align: top; }
table.compare th { background: var(--paper); }
.pill { display: inline-block; border-radius: 99px; padding: 0 8px; font-size: 0.8rem; font-weight: 600; }
.pill.safe { background: var(--safe-bg); color: var(--safe); }
.pill.caution { background: var(--caution-bg); color: var(--caution); }
.pill.dangerous { background: var(--danger-bg); color: var(--danger); }

.footer { max-width: 1180px; margin: 0 auto 30px; padding: 0 16px; font-size: 0.82rem; color: var(--ink-soft); }

/* ---------- public project profile ---------- */
.top { position: sticky; top: 0; z-index: 20; padding: 10px 20px; box-shadow: 0 1px 0 rgba(255,255,255,.08); }
.brand { display: inline-flex; align-items: center; gap: 10px; color: #fff; text-decoration: none; min-width: 250px; }
.brand img { flex: none; }
.brand strong { display: block; font-size: 1rem; line-height: 1.15; }
.brand small { margin-top: 3px; }
.top-actions { display: flex; align-items: center; flex-wrap: wrap; justify-content: flex-end; gap: 9px 13px; }
.site-nav { display: flex; flex-wrap: wrap; gap: 10px; }
.site-nav a, .research-nav { color: #dbeafe; font-size: .82rem; text-decoration: none; white-space: nowrap; }
.site-nav a:hover, .research-nav:hover { color: #fff; text-decoration: underline; }
.language-toggle { border: 1px solid #6681b1; border-radius: 5px; background: transparent; color: #fff; font: inherit; font-size: .78rem; font-weight: 700; padding: 3px 8px; }
.language-toggle:hover { border-color: #fff; }
.project-hero, .story-section, .ownership-section, .contact-section { max-width: 1148px; margin: 18px auto 0; }
.project-hero { display: grid; grid-template-columns: minmax(0, 1.5fr) minmax(280px, .7fr); gap: 24px; padding: 42px 34px; background: linear-gradient(135deg,#103b82,#1f4fbf); color: #fff; border-radius: 8px; overflow: hidden; position: relative; }
.project-hero::after { content: ""; position: absolute; width: 260px; height: 260px; right: -100px; bottom: -160px; border: 36px solid rgba(255,255,255,.09); transform: rotate(18deg); }
.hero-copy, .hero-proof { position: relative; z-index: 1; }.eyebrow { color: #8de5f4; font-size: .76rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; margin: 0 0 8px; }.project-hero h1 { margin: 0; font-size: clamp(2rem,4.2vw,3.45rem); line-height: 1.06; letter-spacing: 0; }.hero-tagline { font-size: 1.25rem; font-weight: 700; margin: 12px 0 6px; }.hero-summary { margin: 0; max-width: 720px; color: #e6efff; }.hero-buttons { display: flex; flex-wrap: wrap; gap: 9px; margin-top: 22px; }.hero-buttons .btn { text-decoration: none; }.hero-buttons .btn:not(.btn-primary) { color: #fff; background: transparent; border-color: #a6c7ff; }.hero-proof { padding: 18px; border: 1px solid rgba(255,255,255,.28); background: rgba(8,28,66,.25); border-radius: 7px; display: grid; align-content: start; gap: 5px; }.hero-proof strong { font-size: 1.02rem; }.hero-proof span:not(.proof-kicker) { color: #dbeafe; font-size: .9rem; }.hero-proof hr { width: 100%; border: 0; border-top: 1px solid rgba(255,255,255,.25); margin: 10px 0; }.proof-kicker { color: #8de5f4; font-size: .73rem; font-weight: 700; text-transform: uppercase; letter-spacing: .07em; }
.story-section { padding: 40px 0 4px; }.section-heading { max-width: 720px; }.section-heading h2, .split-section h2, .ownership-section h2, .contact-section h2 { font-size: 1.75rem; line-height: 1.18; margin: 0; }.feature-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 14px; margin-top: 20px; }.feature-card { background: var(--sheet); border: 1px solid var(--rule); border-radius: 8px; padding: 20px; }.feature-no { color: var(--blue); font-family: var(--mono); font-size: .8rem; font-weight: 700; }.feature-card h3 { margin-top: 12px; }.feature-card p { margin: 0; color: var(--ink-soft); font-size: .93rem; }.split-section { display: grid; grid-template-columns: 1.2fr .8fr; gap: 28px; align-items: stretch; }.split-section > div { padding: 12px 0; }.split-section > div > p:not(.eyebrow) { max-width: 700px; color: var(--ink-soft); }.achievement-card { border-radius: 8px; border: 1px solid #c8d7ef; background: #edf4ff; padding: 22px; }.achievement-card h3 { font-size: 1.16rem; margin: 10px 0 8px; }.achievement-card p { color: var(--ink-soft); }.verification-note { font-size: .83rem; }.ownership-section { margin-top: 42px; padding: 30px; border-radius: 8px; background: #17243a; color: #fff; display: grid; grid-template-columns: 1.2fr .8fr; gap: 24px; }.ownership-section .eyebrow { color: #8de5f4; }.ownership-section p { color: #d4dfef; }.fingerprint { border-left: 1px solid #526988; padding-left: 24px; display: grid; gap: 4px; align-content: center; font-size: .78rem; color: #b9c9e1; }.fingerprint code { color: #fff; overflow-wrap: anywhere; margin-bottom: 9px; }.ownership-note { grid-column: 1 / -1; border-top: 1px solid #526988; padding-top: 16px; margin: 0; font-weight: 600; }.contact-section { padding: 42px 0 54px; display: grid; grid-template-columns: 1.2fr .8fr; gap: 26px; align-items: center; }.contact-section > div > p:not(.eyebrow) { color: var(--ink-soft); max-width: 680px; }.contact-card { border-left: 4px solid var(--blue); padding: 17px 19px; background: #fff; border-radius: 0 8px 8px 0; box-shadow: 0 4px 20px rgba(31,79,191,.08); display: grid; gap: 4px; }.contact-card strong { font-size: 1.02rem; }.contact-card span { color: var(--ink-soft); font-size: .9rem; }
.footer { max-width: none; margin: 0; padding: 20px max(16px,calc((100vw - 1148px)/2)); background: #102036; color: #d6e0ee; display: flex; justify-content: space-between; gap: 14px; }
@media (max-width: 900px) { .project-hero,.split-section,.ownership-section,.contact-section { grid-template-columns: 1fr; }.feature-grid { grid-template-columns: 1fr; }.fingerprint { border-left: 0; border-top: 1px solid #526988; padding: 18px 0 0; }.site-nav { display: none; }.top-inner { align-items: center; }.top-actions { gap: 8px; }.project-hero,.story-section,.ownership-section,.contact-section { margin-left: 16px; margin-right: 16px; }.story-section { padding-left: 0; padding-right: 0; }.contact-section { padding-bottom: 34px; } }
@media (max-width: 560px) { .top { padding: 9px 14px; }.brand { min-width: 0; }.brand small { display: none; }.mode-badge { display: none; }.project-hero { padding: 28px 22px; }.project-hero h1 { font-size: 2rem; }.hero-tagline { font-size: 1.08rem; }.ownership-section { padding: 22px; }.footer { display: grid; } }

/* ---------- trang nghiên cứu ---------- */
.research-main { max-width: 1180px; margin: 16px auto 40px; padding: 0 16px; display: grid; gap: 16px; }
.grid2 { display: grid; gap: 4px 14px; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); }
.check { display: inline-flex; gap: 6px; align-items: center; font-weight: 400; }
.warn { background: var(--caution-bg); border-left: 4px solid var(--caution); padding: 10px 14px; border-radius: var(--radius-sm); margin: 8px 0; }
.table-wrap { overflow-x: auto; }
table.data { width: 100%; border-collapse: collapse; font-size: 0.88rem; }
table.data th, table.data td { border-bottom: 1px solid var(--rule); padding: 6px 8px; text-align: left; vertical-align: top; }
table.data th { background: var(--paper); }
table.data td.clip { max-width: 300px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.confusion { display: inline-grid; grid-template-columns: auto auto auto; gap: 2px; font-size: 0.85rem; margin: 4px 12px 8px 0; }
.confusion span { padding: 4px 8px; background: var(--paper); text-align: center; }
.confusion span.h { background: transparent; font-weight: 600; }