/* ==========================================================================
   Chấm bài tự động — CSE426
   Bảng màu: giấy kẻ lạnh, mực xanh đậm, điểm nhấn cobalt.
   Chữ: Be Vietnam Pro (giao diện) + JetBrains Mono (mã nguồn, số liệu).
   ========================================================================== */

:root {
  --paper:      #eef1f6;
  --surface:    #ffffff;
  --surface-2:  #f7f9fc;
  --ink:        #131d2b;
  --ink-2:      #3d4a5e;
  --muted:      #6b7a90;
  --rule:       #d5dce7;
  --rule-soft:  #e6ebf2;

  --accent:     #2f53d6;
  --accent-ink: #1d3aa8;
  --accent-bg:  #e8edfd;

  --ac:   #0e8a5f;  --ac-bg:   #e2f4ec;
  --wa:   #cb3527;  --wa-bg:   #fbe8e6;
  --tle:  #a8710f;  --tle-bg:  #fcf0dc;
  --re:   #6d4ab5;  --re-bg:   #eee9fa;
  --idle: #9aa8bc;  --idle-bg: #eaeef4;

  --sans: "Be Vietnam Pro", "Segoe UI", system-ui, sans-serif;
  --mono: "JetBrains Mono", "Cascadia Mono", "Consolas", ui-monospace, monospace;

  --r: 6px;
  --shadow: 0 1px 2px rgba(19, 29, 43, .06), 0 8px 24px -12px rgba(19, 29, 43, .18);
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.6;
}

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

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 3px;
}

.wrap { max-width: 940px; margin: 0 auto; padding: 0 20px; }

/* --- Thanh đầu trang ----------------------------------------------------- */

.masthead {
  background: var(--ink);
  color: #fff;
  border-bottom: 3px solid var(--accent);
}
.masthead-in {
  display: flex; align-items: center; justify-content: space-between;
  gap: 16px; min-height: 58px; flex-wrap: wrap;
}
.brand { display: flex; align-items: baseline; gap: 10px; color: #fff; }
.brand:hover { text-decoration: none; }
.brand-code {
  font-family: var(--mono); font-weight: 700; font-size: 13px;
  letter-spacing: .08em;
  background: var(--accent); padding: 2px 7px; border-radius: 3px;
}
.brand-name { font-weight: 600; letter-spacing: -.01em; }
.nav { display: flex; gap: 20px; font-size: 14px; }
.nav a + a { margin-left: 20px; }
@supports (gap: 20px) { .nav a + a { margin-left: 0; } }
.nav a { color: #c3cee2; }
.nav a:hover { color: #fff; text-decoration: none; }

/* --- Tiêu đề trang ------------------------------------------------------- */

.page-head { padding: 34px 0 22px; }
.eyebrow {
  font-family: var(--mono); font-size: 11px; font-weight: 500;
  letter-spacing: .14em; text-transform: uppercase; color: var(--muted);
}
h1 {
  font-size: clamp(24px, 4vw, 33px); font-weight: 800;
  letter-spacing: -.025em; line-height: 1.2; margin: 6px 0 0;
}
h2 { font-size: 18px; font-weight: 600; letter-spacing: -.01em; margin: 30px 0 12px; }
h3 { font-size: 15px; font-weight: 600; margin: 20px 0 8px; }
.lead { color: var(--ink-2); max-width: 62ch; margin-top: 10px; }

/* --- Thẻ & khối ---------------------------------------------------------- */

.card {
  background: var(--surface);
  border: 1px solid var(--rule);
  border-radius: var(--r);
  padding: 20px;
  margin-bottom: 18px;
}
.card-tight { padding: 14px 16px; }

/* --- Danh sách bài tập --------------------------------------------------- */

.chapter { margin-bottom: 26px; }
.chapter-head {
  display: flex; align-items: center; gap: 12px;
  padding-bottom: 8px; border-bottom: 1px solid var(--rule);
  margin-bottom: 2px;
}
.chapter-head h2 { margin: 0; }
.chapter-count {
  font-family: var(--mono); font-size: 12px; color: var(--muted); margin-left: 12px;
}
@supports (gap: 12px) { .chapter-count { margin-left: 0; } }
.prob-row {
  display: flex; align-items: center; gap: 14px;
  padding: 13px 4px; border-bottom: 1px solid var(--rule-soft);
}
.prob-row:hover { background: var(--surface); }
.prob-id {
  font-family: var(--mono); font-size: 12px; font-weight: 700;
  color: var(--accent-ink); background: var(--accent-bg);
  padding: 3px 7px; border-radius: 3px; white-space: nowrap;
}
.prob-title { flex: 1; font-weight: 500; }
.prob-title a { color: var(--ink); }
.prob-meta { font-family: var(--mono); font-size: 12px; color: var(--muted); white-space: nowrap; }

/* --- Biểu mẫu ------------------------------------------------------------ */

.field { margin-bottom: 14px; }
label {
  display: block; font-size: 13px; font-weight: 500;
  color: var(--ink-2); margin-bottom: 5px;
}
input[type=text], select, textarea {
  width: 100%; font-family: var(--sans); font-size: 14px;
  color: var(--ink); background: var(--surface);
  border: 1px solid var(--rule); border-radius: var(--r);
  padding: 9px 11px;
}
input[type=text]:focus, select:focus, textarea:focus {
  border-color: var(--accent); outline: none;
  box-shadow: 0 0 0 3px var(--accent-bg);
}
.row-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }

.editor-wrap { border: 1px solid var(--rule); border-radius: var(--r); overflow: hidden; }
.editor-bar {
  display: flex; align-items: center; justify-content: space-between;
  gap: 10px; padding: 7px 11px; background: var(--surface-2);
  border-bottom: 1px solid var(--rule);
  font-family: var(--mono); font-size: 11px; color: var(--muted);
}
textarea.code {
  display: block; width: 100%; min-height: 320px; resize: vertical;
  font-family: var(--mono); font-size: 13px; line-height: 1.65;
  border: 0; border-radius: 0; padding: 12px 14px;
  tab-size: 4; white-space: pre; overflow-wrap: normal; overflow-x: auto;
}
textarea.code:focus { box-shadow: none; }
.editor-wrap.drag { border-color: var(--accent); background: var(--accent-bg); }

.btn {
  display: inline-flex; align-items: center; gap: 8px;
  font-family: var(--sans); font-size: 14px; font-weight: 600;
  color: #fff; background: var(--accent);
  border: 0; border-radius: var(--r); padding: 11px 20px; cursor: pointer;
}
.btn:hover { background: var(--accent-ink); text-decoration: none; }
.btn:disabled { background: var(--idle); cursor: not-allowed; }
.btn-ghost {
  color: var(--ink-2); background: transparent; border: 1px solid var(--rule);
  font-weight: 500; padding: 9px 16px;
}
.btn-ghost:hover { background: var(--surface-2); color: var(--ink); }
.actions { display: flex; align-items: center; gap: 14px; margin-top: 16px; flex-wrap: wrap; }
.hint { font-size: 13px; color: var(--muted); }
.err {
  color: var(--wa); background: var(--wa-bg);
  border: 1px solid #f0c8c3; border-radius: var(--r);
  padding: 10px 13px; font-size: 14px; margin-bottom: 14px;
}

/* --- Đề bài -------------------------------------------------------------- */

.statement { color: var(--ink-2); }
.statement h2 { font-size: 16px; margin: 22px 0 8px; color: var(--ink); }
.statement code {
  font-family: var(--mono); font-size: 13px;
  background: var(--surface-2); border: 1px solid var(--rule-soft);
  padding: 1px 5px; border-radius: 3px;
}
.statement pre {
  background: var(--surface-2); border: 1px solid var(--rule);
  border-radius: var(--r); padding: 12px 14px; overflow-x: auto;
}
.statement pre code { background: none; border: 0; padding: 0; }
.statement ul { padding-left: 20px; }

.sample-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.sample-box { border: 1px solid var(--rule); border-radius: var(--r); overflow: hidden; }
.sample-box header {
  font-family: var(--mono); font-size: 11px; letter-spacing: .1em;
  text-transform: uppercase; color: var(--muted);
  background: var(--surface-2); border-bottom: 1px solid var(--rule);
  padding: 6px 11px;
}
.sample-box pre {
  margin: 0; padding: 11px 13px; font-family: var(--mono);
  font-size: 13px; line-height: 1.6; overflow-x: auto; background: var(--surface);
}

/* --- DẢI TEST (phần đặc trưng của giao diện) ------------------------------ */

.verdict-panel {
  background: var(--surface); border: 1px solid var(--rule);
  border-radius: var(--r); overflow: hidden; margin-bottom: 20px;
}
.verdict-top {
  display: flex; align-items: center; gap: 22px;
  padding: 20px 22px; border-bottom: 1px solid var(--rule-soft); flex-wrap: wrap;
}
.score-block { display: flex; align-items: baseline; gap: 3px; }
.score-now {
  font-family: var(--mono); font-weight: 700; font-size: 46px;
  letter-spacing: -.04em; line-height: 1; font-variant-numeric: tabular-nums;
}
.score-max { font-family: var(--mono); font-size: 20px; color: var(--muted); letter-spacing: -.02em; }
.verdict-meta { flex: 1; min-width: 190px; }
.verdict-label { font-size: 17px; font-weight: 600; letter-spacing: -.01em; }
.verdict-sub { font-size: 13px; color: var(--muted); font-family: var(--mono); }

.strip {
  display: flex; flex-wrap: wrap; gap: 4px;
  padding: 16px 22px; background: var(--surface-2);
  border-bottom: 1px solid var(--rule-soft);
}
.cell {
  width: 40px; height: 40px; border-radius: 3px;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  font-family: var(--mono); font-size: 11px; font-weight: 700; line-height: 1.15;
  background: var(--idle-bg); color: var(--idle);
  border: 1px solid transparent;
  transition: background .18s ease, color .18s ease, border-color .18s ease;
}
.cell small { font-size: 9px; font-weight: 500; opacity: .8; }
.cell.pending { animation: pulse 1.4s ease-in-out infinite; }
.cell.AC  { background: var(--ac-bg);  color: var(--ac);  border-color: #b9e2d1; }
.cell.WA  { background: var(--wa-bg);  color: var(--wa);  border-color: #f0c8c3; }
.cell.TLE { background: var(--tle-bg); color: var(--tle); border-color: #efd9ab; }
.cell.MLE { background: var(--tle-bg); color: var(--tle); border-color: #efd9ab; }
.cell.RE, .cell.SE { background: var(--re-bg); color: var(--re); border-color: #d6cbef; }

@keyframes pulse { 0%, 100% { opacity: .45; } 50% { opacity: 1; } }
@media (prefers-reduced-motion: reduce) {
  .cell.pending { animation: none; opacity: .6; }
  .cell { transition: none; }
}

/* --- Bảng chi tiết test -------------------------------------------------- */

table.grid { width: 100%; border-collapse: collapse; font-size: 14px; }
table.grid th {
  text-align: left; font-family: var(--mono); font-size: 11px;
  letter-spacing: .1em; text-transform: uppercase; color: var(--muted);
  font-weight: 500; padding: 9px 12px; border-bottom: 1px solid var(--rule);
  background: var(--surface-2);
}
table.grid td { padding: 9px 12px; border-bottom: 1px solid var(--rule-soft); vertical-align: top; }
table.grid tr:last-child td { border-bottom: 0; }
.num { font-family: var(--mono); font-variant-numeric: tabular-nums; white-space: nowrap; }
.note { color: var(--muted); font-size: 13px; }

.tag {
  display: inline-block; font-family: var(--mono); font-size: 11px; font-weight: 700;
  padding: 2px 7px; border-radius: 3px; letter-spacing: .02em;
}
.tag.AC { background: var(--ac-bg); color: var(--ac); }
.tag.WA { background: var(--wa-bg); color: var(--wa); }
.tag.TLE, .tag.MLE { background: var(--tle-bg); color: var(--tle); }
.tag.RE, .tag.CE, .tag.SE { background: var(--re-bg); color: var(--re); }
.tag.pending { background: var(--idle-bg); color: var(--idle); }

pre.log {
  font-family: var(--mono); font-size: 12.5px; line-height: 1.6;
  background: #1b2534; color: #e4eaf3; border-radius: var(--r);
  padding: 14px 16px; overflow-x: auto; white-space: pre-wrap;
}
pre.code-view {
  font-family: var(--mono); font-size: 13px; line-height: 1.65;
  background: var(--surface-2); border: 1px solid var(--rule);
  border-radius: var(--r); padding: 14px 16px; overflow-x: auto;
}
.diff-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin-top: 8px; }

/* --- Trống & chân trang -------------------------------------------------- */

.empty {
  border: 1px dashed var(--rule); border-radius: var(--r);
  padding: 30px; text-align: center; color: var(--muted);
}
.foot {
  margin-top: 46px; padding: 18px 0 30px;
  border-top: 1px solid var(--rule);
  font-size: 12.5px; color: var(--muted);
}

@media (max-width: 640px) {
  .row-2, .sample-grid, .diff-grid { grid-template-columns: 1fr; }
  .score-now { font-size: 38px; }
  .cell { width: 34px; height: 34px; }
  .hide-sm { display: none; }
}


/* --- Dự phòng cho trình duyệt cũ không hỗ trợ flex gap (phòng máy dùng bản Windows cũ) --- */
.verdict-top > * + *  { margin-left: 22px; }
.score-block > * + *  { margin-left: 3px; }
.actions > * + *      { margin-left: 14px; }
.strip .cell          { margin: 0 4px 4px 0; }
.chapter-head > * + * { margin-left: 12px; }
@supports (gap: 1px) {
  .verdict-top > * + *  { margin-left: 0; }
  .score-block > * + *  { margin-left: 0; }
  .actions > * + *      { margin-left: 0; }
  .strip .cell          { margin: 0; }
  .chapter-head > * + * { margin-left: 0; }
}


/* --- Nút sao chép trên khối test mẫu --- */
.sample-box header {
  display: flex; align-items: center; justify-content: space-between; gap: 10px;
}
.sao-chep {
  font-family: var(--sans); font-size: 11px; font-weight: 500;
  color: var(--accent-ink); background: transparent;
  border: 1px solid var(--rule); border-radius: 3px;
  padding: 1px 7px; cursor: pointer; text-transform: none; letter-spacing: 0;
}
.sao-chep:hover { background: var(--accent-bg); border-color: var(--accent); }

/* Thông báo sau khi thao tác: sửa tên, xoá, lưu mốc chốt… */
.bao-tin{ margin:14px 0 0; border-left:4px solid var(--ac); }
.bao-ok { border-left-color:#0a7c3f; background:#f2fbf6; }
.bao-loi{ border-left-color:#b3261e; background:#fdf5f4; }