:root {
  color-scheme: dark;
  --ink: #f2f0ed;
  --muted: #a3a3a3;
  --paper: #191919;
  --surface: #212121;
  --surface-strong: #0d0d0d;
  --surface-soft: #2a292a;
  --card: #212121;
  --line: #403f40;
  --line-strong: #666;
  --accent: #b83642;
  --accent-deep: #602127;
  --accent-soft: #d7a5aa;
  --light-panel: #fafafa;
  --light-ink: #252324;
  --success: #75b69e;
  --danger: #e46f78;
  --shadow: 0 18px 55px rgba(0, 0, 0, .3);
  --display: Georgia, "Times New Roman", "Noto Serif TC", serif;
  --sans: "Open Sans", Inter, "Noto Sans TC", system-ui, sans-serif;
}

* { box-sizing: border-box; }
html { background: var(--paper); color: var(--ink); font-family: var(--sans); scroll-behavior: smooth; }
body {
  min-width: 320px;
  margin: 0;
  background:
    linear-gradient(90deg, transparent calc(50% - 1px), rgba(255,255,255,.018) 50%, transparent calc(50% + 1px)),
    radial-gradient(circle at 12% 8%, #303030 0, transparent 26rem),
    var(--paper);
  line-height: 1.65;
}
::selection { background: var(--accent); color: #fff; }

a {
  color: inherit;
  text-decoration: none;
  transition: color .12s ease;
}
a:hover, a:focus-visible, .link-button:hover, .link-button:focus-visible {
  color: hsl(var(--random-hue, 354) 60% 62%);
}
.random-hover-content { display: inline-block; transform: rotate(0); transform-origin: center; transition: transform .14s cubic-bezier(.2,.8,.2,1), background-color .12s ease, border-color .12s ease, color .12s ease; }
a:hover > .random-hover-content, a:focus-visible > .random-hover-content, button:hover > .random-hover-content, button:focus-visible > .random-hover-content { transform: rotate(var(--random-angle, 3deg)); }

.topbar {
  position: sticky;
  z-index: 50;
  top: 0;
  min-height: 72px;
  padding: 0 max(24px, calc((100vw - 1240px) / 2));
  border-bottom: 1px solid var(--line);
  background: rgba(13, 13, 13, .94);
  display: flex;
  align-items: stretch;
  justify-content: space-between;
  backdrop-filter: blur(16px);
}
.brand {
  position: relative;
  display: flex;
  max-width: 300px;
  padding: 0 22px 0 0;
  align-items: center;
  font-family: var(--display);
  font-size: 1.08rem;
  line-height: 1.2;
}
.brand::before {
  width: 10px;
  height: 10px;
  margin-right: 13px;
  border: 1px solid var(--accent);
  content: "";
  transform: rotate(45deg);
}
.topbar nav { display: flex; align-items: stretch; gap: 0; font-size: .78rem; letter-spacing: .035em; }
.topbar nav > a, .topbar nav > form { display: flex; align-items: stretch; }
.topbar nav > a { position: relative; padding: 0 13px; align-items: center; }
.topbar nav > a::after {
  position: absolute;
  right: 13px;
  bottom: 0;
  left: 13px;
  height: 2px;
  background: currentColor;
  content: "";
  transform: scaleX(0);
  transform-origin: left;
  transition: transform .16s ease;
}
.topbar nav > a:hover::after, .topbar nav > a:focus-visible::after { transform: scaleX(1); }
.nav-divider { width: 1px; height: 28px; margin: auto 10px; background: var(--line); flex: 0 0 1px; }
.signed-in-user {
  display: flex;
  min-width: 115px;
  margin-left: 10px;
  padding: 0 16px;
  border-left: 1px solid var(--line);
  align-items: flex-start;
  flex-direction: column;
  justify-content: center;
  line-height: 1.2;
  white-space: nowrap;
}
.signed-in-user strong { font-family: var(--display); font-size: .9rem; font-weight: 400; }
.signed-in-user small { margin-top: 3px; color: var(--accent-soft); font-size: .64rem; letter-spacing: .08em; }

.shell { width: min(1240px, 100%); min-height: calc(100vh - 132px); margin: auto; padding: 58px 28px 100px; }
footer { padding: 30px; border-top: 1px solid var(--line); color: var(--muted); font-size: .72rem; letter-spacing: .08em; text-align: center; text-transform: uppercase; }

h1, h2, h3 { font-family: var(--display); font-weight: 400; }
h1 { margin: .18em 0; font-size: clamp(2.35rem, 6vw, 4.9rem); letter-spacing: -.045em; line-height: .98; }
h2 { margin: 1.8em 0 .8em; font-size: clamp(1.45rem, 3vw, 2rem); line-height: 1.16; }
h3 { margin: .5em 0; font-size: 1.25rem; line-height: 1.28; }
p { margin: .55em 0; }
small { display: block; }
.muted, small { color: var(--muted); }
.eyebrow {
  color: var(--accent-soft);
  font-size: .67rem;
  font-weight: 700;
  letter-spacing: .18em;
  text-transform: uppercase;
}
.eyebrow::before { margin-right: 8px; color: var(--accent); content: "◆"; font-size: .62rem; }

.hero {
  position: relative;
  min-height: 330px;
  margin-bottom: 58px;
  padding: clamp(34px, 6vw, 72px);
  overflow: hidden;
  border: 1px solid var(--line);
  background: linear-gradient(125deg, rgba(255,255,255,.035), transparent 60%), var(--surface-strong);
  box-shadow: var(--shadow);
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
}
.hero::after {
  position: absolute;
  right: -70px;
  bottom: -140px;
  width: 340px;
  height: 340px;
  border: 1px solid var(--accent-deep);
  content: "";
  transform: rotate(38deg);
  pointer-events: none;
}
.hero > * { position: relative; z-index: 1; }
.hero p { max-width: 700px; color: #c8c6c6; }
.hero.compact { min-height: 230px; padding: 40px 46px; }
.section-title, .page-heading { display: flex; margin-bottom: 28px; align-items: flex-end; justify-content: space-between; gap: 28px; }
.section-title h1, .section-title h2, .page-heading h1 { margin: 0; }

.card-grid, .assignment-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(270px, 1fr)); gap: 1px; background: var(--line); border: 1px solid var(--line); }
.course-card, .assignment-card, .panel, .article, .comment {
  border: 1px solid var(--line);
  background: var(--card);
  box-shadow: var(--shadow);
}
.course-card, .assignment-card { padding: 28px; box-shadow: none; transition: background .16s ease, border-color .16s ease; }
.card-grid > .course-card, .assignment-grid > .assignment-card { border: 0; }
.course-card:hover, .assignment-card:hover { border-color: var(--accent); background: #292829; }
.course-card p, .assignment-card p { color: var(--muted); }
.course-card p { min-height: 3em; }
.arrow { color: var(--accent-soft); font-size: .78rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; }
.profile-link { --hover-lightness: 40%; text-decoration: none; }
.profile-link > .random-hover-content { padding: 7px 9px; border: 1px solid transparent; background: transparent; display: inline-grid; }
.profile-link:hover, .profile-link:focus-visible { color: #fff; text-decoration: none; }
.profile-link:hover > .random-hover-content, .profile-link:focus-visible > .random-hover-content { border-color: hsl(var(--random-hue, 354) 60% var(--hover-lightness)); background: hsl(var(--random-hue, 354) 60% var(--hover-lightness)); }
.assignment-card { display: flex; justify-content: space-between; gap: 20px; }
.assignment-card p { display: -webkit-box; overflow: hidden; -webkit-box-orient: vertical; -webkit-line-clamp: 2; }
.panel, .article, .comment { padding: clamp(22px, 4vw, 36px); }

.list { display: grid; gap: 1px; border: 1px solid var(--line); background: var(--line); }
.list-row { padding: 16px 19px; background: var(--surface); display: flex; align-items: center; justify-content: space-between; gap: 18px; }
.list a.list-row:hover { background: #2c2b2c; }
.with-avatar { display: flex; align-items: center; gap: 13px; }
.with-avatar img, .person img { width: 48px; height: 48px; border: 1px solid var(--line); border-radius: 50%; object-fit: cover; filter: grayscale(1); }
.people-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 1px; border: 1px solid var(--line); background: var(--line); }
.person { padding: 17px; background: var(--surface); display: flex; align-items: center; gap: 14px; }
.person:hover { background: #2c2b2c; }

.status { display: inline-block; padding: 4px 9px; border: 1px solid var(--line-strong); color: #d0cece; background: transparent; font-size: .68rem; font-weight: 700; letter-spacing: .04em; white-space: nowrap; }
.status.done { border-color: #456f60; color: #9bd7c0; }
.status.open { border-color: var(--accent); color: var(--accent-soft); }
.status.late { border-color: #8b4248; color: #f09aa1; }
.actions, .inline { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; }

.button, button:not(.link-button) {
  --button-bg: var(--accent);
  --button-ink: #fff;
  --hover-lightness: 40%;
  position: relative;
  z-index: 0;
  min-height: 42px;
  padding: 11px 18px;
  border: 0;
  border-radius: 0;
  background: transparent;
  color: var(--button-ink);
  cursor: pointer;
  font: 700 .75rem/1.2 var(--sans);
  letter-spacing: .055em;
  text-transform: uppercase;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  isolation: isolate;
}
.button::before, button:not(.link-button)::before {
  position: absolute;
  z-index: -1;
  inset: 0;
  border: 1px solid color-mix(in srgb, var(--button-bg), white 12%);
  background: var(--button-bg);
  content: "";
  transform: rotate(0);
  transition: transform .14s cubic-bezier(.2,.8,.2,1), background-color .12s ease, border-color .12s ease;
}
.button:hover, .button:focus-visible, button:not(.link-button):hover, button:not(.link-button):focus-visible { color: var(--button-ink); }
.button > .random-hover-content, button > .random-hover-content { display: inline-flex; align-items: center; justify-content: center; }
.button:hover::before, .button:focus-visible::before, button:not(.link-button):hover::before, button:not(.link-button):focus-visible::before {
  border-color: hsl(var(--random-hue, 354) 60% var(--hover-lightness));
  background: hsl(var(--random-hue, 354) 60% var(--hover-lightness));
  transform: rotate(var(--random-angle, 3deg));
}
.button.secondary, button.secondary, button.danger {
  --button-bg: #e7e5e2;
  --button-ink: #201f20;
  --hover-lightness: 76%;
}
.button.ghost, .button.ghost-dark {
  --button-bg: transparent;
  --button-ink: var(--ink);
  --hover-lightness: 76%;
}
.button.ghost::before, .button.ghost-dark::before { border-color: var(--line-strong); }
button.danger { --button-bg: var(--accent-deep); --button-ink: #fff; --hover-lightness: 40%; }
button.small, .button.small { min-height: 32px; padding: 7px 11px; font-size: .66rem; }
.full { width: 100%; margin-top: 14px; }
.link-button { padding: 0 13px; border: 0; background: none; color: inherit; cursor: pointer; font: inherit; }
button:disabled { opacity: .4; cursor: not-allowed; }
button:disabled::before { transform: none !important; background: #555 !important; border-color: #666 !important; }
button:disabled > .random-hover-content { transform: none !important; }

.stack { display: grid; gap: 17px; }
.form-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; }
.span-2 { grid-column: span 2; }
label { color: #c8c5c5; font-size: .72rem; font-weight: 700; letter-spacing: .045em; display: grid; gap: 7px; }
input, textarea, select {
  width: 100%;
  padding: 12px 13px;
  border: 1px solid var(--line);
  border-radius: 0;
  outline: 0;
  background: #111;
  color: var(--ink);
  font: inherit;
  transition: border-color .12s ease, box-shadow .12s ease;
}
input:focus, textarea:focus, select:focus { border-color: var(--accent); box-shadow: inset 3px 0 0 var(--accent); }
input[type="file"] { padding: 8px; }
input[type="checkbox"] { accent-color: var(--accent); }
textarea { resize: vertical; }
.check { grid-auto-flow: column; align-items: center; justify-content: start; }
.check input { width: auto; }
.auth-card, .narrow { max-width: 540px; margin: 36px auto; padding: clamp(30px, 6vw, 54px); border: 1px solid var(--line); background: var(--surface); box-shadow: var(--shadow); }
.auth-card { border-top: 3px solid var(--accent); }
.narrow-left { max-width: 760px; }
.two-column, .info-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; align-items: start; }
.breadcrumb { margin-bottom: 28px; color: var(--accent-soft); font-size: .78rem; font-weight: 700; letter-spacing: .04em; }
.deadline { min-width: 250px; display: grid; }
.deadline small { margin-top: 11px; color: var(--accent-soft); }

.table-wrap { overflow-x: auto; border: 1px solid var(--line); background: var(--surface); box-shadow: var(--shadow); }
table { width: 100%; border-collapse: collapse; }
th, td { padding: 14px 16px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: middle; }
th { background: #101010; color: var(--muted); font-size: .66rem; letter-spacing: .11em; text-transform: uppercase; }
tbody tr { transition: background .12s ease; }
tbody tr:hover { background: #2a292a; }
tbody tr:last-child td { border-bottom: 0; }
td small { margin-top: 3px; }

.article header, .comment header { display: flex; align-items: center; justify-content: space-between; }
.article-body { max-width: 800px; padding: 34px 0; font-size: 1.06rem; }
.comment-list { display: grid; gap: 1px; border: 1px solid var(--line); background: var(--line); }
.comment { border: 0; box-shadow: none; }
.score-chip { padding: 5px 10px; border: 1px solid var(--accent); color: var(--accent-soft); font-weight: 800; }
.score { color: var(--accent-soft); font: 400 4rem/1 var(--display); }
.score small { display: inline; font: 1rem var(--sans); }
.distribution { display: flex; align-items: flex-end; gap: 12px; }
.distribution span { display: grid; gap: 5px; text-align: center; }
.distribution i { width: 22px; height: calc(5px + var(--count) * 12px); border: 1px solid var(--accent); background: var(--accent-deep); }

.profile-hero { display: grid; grid-template-columns: 230px 1fr; margin-bottom: 42px; align-items: center; gap: 45px; }
.profile-hero > img, .avatar-large { width: 220px; height: 220px; border: 1px solid var(--line); border-radius: 0; object-fit: cover; filter: grayscale(1); }
.profile-bio { margin-bottom: 28px; border-top: 3px solid var(--accent); }
.profile-bio .markdown-body { max-width: 860px; }
.clean-list { padding: 0; list-style: none; }
.clean-list li { padding: 10px 0; border-bottom: 1px solid var(--line); display: flex; justify-content: space-between; gap: 20px; }
.stats { display: grid; grid-template-columns: repeat(4, 1fr); margin-bottom: 30px; gap: 1px; border: 1px solid var(--line); background: var(--line); }
.stats div { padding: 28px; background: var(--surface-strong); }
.stats strong { color: var(--accent-soft); font: 400 2.5rem var(--display); display: block; }
.alert { margin-bottom: 24px; padding: 15px 18px; border: 1px solid var(--line); background: var(--surface); }
.alert.success { border-left: 4px solid var(--success); color: #bde2d4; }
.alert.error { border-left: 4px solid var(--danger); color: #f3b6bb; }
.empty { padding: 72px 30px; text-align: center; }
.preline { white-space: pre-line; }
.break { overflow-wrap: anywhere; }
.compact-list { max-height: 480px; overflow: auto; }
code { padding: 2px 6px; background: #090909; color: var(--accent-soft); font-size: .9em; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .001ms !important; animation-duration: .001ms !important; }
  .button:hover::before, .button:focus-visible::before, button:not(.link-button):hover::before, button:not(.link-button):focus-visible::before { transform: none; }
  a:hover > .random-hover-content, a:focus-visible > .random-hover-content, button:hover > .random-hover-content, button:focus-visible > .random-hover-content { transform: none; }
}

@media (max-width: 900px) {
  .topbar { padding: 0 16px; }
  .brand { max-width: 220px; }
  .topbar nav > a, .link-button { padding-right: 8px; padding-left: 8px; }
  .signed-in-user { min-width: auto; padding: 0 10px; }
}

@media (max-width: 760px) {
  .topbar { position: relative; padding: 15px 17px; align-items: flex-start; flex-direction: column; gap: 12px; }
  .brand { max-width: none; min-height: 34px; }
  .topbar nav { width: 100%; overflow-x: auto; padding-bottom: 3px; align-items: center; }
  .topbar nav > a, .link-button { min-height: 38px; white-space: nowrap; }
  .nav-divider { margin: auto 5px; }
  .signed-in-user { margin-left: 5px; min-height: 38px; }
  .shell { padding: 36px 17px 76px; }
  .hero { min-height: 300px; padding: 32px 25px; display: block; }
  .hero .actions { margin-top: 24px; }
  .hero.compact { padding: 30px 25px; }
  .section-title, .page-heading { display: block; }
  .section-title > .button, .page-heading > .button, .page-heading > .actions { margin-top: 20px; }
  .two-column, .info-grid, .profile-hero, .form-grid { grid-template-columns: 1fr; }
  .span-2 { grid-column: auto; }
  .stats { grid-template-columns: 1fr 1fr; }
  .assignment-card { display: block; }
  .profile-hero > img, .avatar-large { width: 150px; height: 150px; }
  .article header { align-items: flex-start; flex-direction: column; gap: 18px; }
}