:root {
  color-scheme: light;
  --home-bg: #f5f5f7;
  --home-surface: rgba(255, 255, 255, 0.86);
  --home-surface-solid: #ffffff;
  --home-text: #1d1d1f;
  --home-text-2: #515154;
  --home-text-3: #6e6e73;
  --home-line: rgba(29, 29, 31, 0.11);
  --home-line-strong: rgba(29, 29, 31, 0.18);
  --home-blue: #0066cc;
  --home-blue-hover: #004f9f;
  --home-blue-soft: #eaf3ff;
  --home-orange: #a44700;
  --home-orange-soft: #fff3e6;
  --home-green: #18794e;
  --home-green-soft: #eaf8f0;
  --home-red: #b42318;
  --home-shadow: 0 18px 48px rgba(29, 29, 31, 0.08);
  --home-font: -apple-system, BlinkMacSystemFont, "SF Pro Text", "SF Pro Display", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --home-mono: ui-monospace, "SFMono-Regular", Menlo, Monaco, Consolas, monospace;
  --home-shell: min(1180px, calc(100% - 48px));
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --home-bg: #0e0e10;
  --home-surface: rgba(29, 29, 31, 0.86);
  --home-surface-solid: #1c1c1e;
  --home-text: #f5f5f7;
  --home-text-2: #d1d1d6;
  --home-text-3: #a1a1a6;
  --home-line: rgba(255, 255, 255, 0.12);
  --home-line-strong: rgba(255, 255, 255, 0.2);
  --home-blue: #2997ff;
  --home-blue-hover: #66b5ff;
  --home-blue-soft: rgba(41, 151, 255, 0.14);
  --home-orange: #ffb340;
  --home-orange-soft: rgba(255, 159, 10, 0.14);
  --home-green: #5bd58c;
  --home-green-soft: rgba(48, 209, 88, 0.14);
  --home-red: #ff6961;
  --home-shadow: 0 18px 54px rgba(0, 0, 0, 0.34);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]):not([data-theme="dark"]) {
    color-scheme: dark;
    --home-bg: #0e0e10;
    --home-surface: rgba(29, 29, 31, 0.86);
    --home-surface-solid: #1c1c1e;
    --home-text: #f5f5f7;
    --home-text-2: #d1d1d6;
    --home-text-3: #a1a1a6;
    --home-line: rgba(255, 255, 255, 0.12);
    --home-line-strong: rgba(255, 255, 255, 0.2);
    --home-blue: #2997ff;
    --home-blue-hover: #66b5ff;
    --home-blue-soft: rgba(41, 151, 255, 0.14);
    --home-orange: #ffb340;
    --home-orange-soft: rgba(255, 159, 10, 0.14);
    --home-green: #5bd58c;
    --home-green-soft: rgba(48, 209, 88, 0.14);
    --home-red: #ff6961;
    --home-shadow: 0 18px 54px rgba(0, 0, 0, 0.34);
  }
}

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

html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at 12% 4%, color-mix(in srgb, var(--home-blue) 10%, transparent), transparent 30rem),
    var(--home-bg);
  color: var(--home-text);
  font-family: var(--home-font);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: inherit; }

button, a { -webkit-tap-highlight-color: transparent; }

button { font: inherit; }

.skip-link {
  position: fixed;
  top: 10px;
  left: 12px;
  z-index: 100;
  transform: translateY(-160%);
  padding: 9px 14px;
  border-radius: 10px;
  background: var(--home-text);
  color: var(--home-bg);
  text-decoration: none;
}

.skip-link:focus { transform: translateY(0); }

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  border-bottom: 1px solid var(--home-line);
  background: color-mix(in srgb, var(--home-bg) 82%, transparent);
  -webkit-backdrop-filter: saturate(160%) blur(22px);
  backdrop-filter: saturate(160%) blur(22px);
}

.site-header__inner {
  width: var(--home-shell);
  min-height: 58px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 650;
  letter-spacing: -0.02em;
  text-decoration: none;
  white-space: nowrap;
}

.brand__mark {
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  border-radius: 9px;
  background: var(--home-text);
  color: var(--home-bg);
  font-family: var(--home-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: -0.05em;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 22px;
  margin-left: auto;
  font-size: 14px;
  color: var(--home-text-2);
}

.site-nav a {
  text-decoration: none;
  transition: color 140ms ease;
}

.site-nav a:hover { color: var(--home-text); }

.appearance-toggle {
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border: 0;
  border-radius: 50%;
  background: transparent;
  color: var(--home-text-2);
  cursor: pointer;
  flex: 0 0 44px;
}

.appearance-toggle:hover { background: var(--home-line); color: var(--home-text); }
.appearance-toggle svg { width: 19px; height: 19px; fill: none; stroke: currentColor; stroke-width: 1.8; }

main { overflow: clip; }

.hero {
  width: var(--home-shell);
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(320px, 0.85fr);
  gap: clamp(42px, 7vw, 96px);
  align-items: center;
  padding: clamp(76px, 10vw, 132px) 0 clamp(72px, 9vw, 112px);
}

.hero > * { min-width: 0; }

.eyebrow {
  margin: 0 0 14px;
  color: var(--home-blue);
  font-size: 13px;
  font-weight: 650;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.hero h1 {
  max-width: 12ch;
  margin: 0;
  font-size: clamp(44px, 6.1vw, 78px);
  line-height: 1.04;
  letter-spacing: -0.055em;
  text-wrap: balance;
}

.hero__lede {
  max-width: 34em;
  margin: 28px 0 0;
  color: var(--home-text-2);
  font-size: clamp(18px, 1.4vw, 22px);
  line-height: 1.65;
  overflow-wrap: anywhere;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 34px;
}

.button {
  min-height: 46px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 0 20px;
  border: 1px solid transparent;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  transition: background 140ms ease, color 140ms ease, border-color 140ms ease, transform 140ms ease;
}

.button:hover { transform: translateY(-1px); }
.button--primary { background: var(--home-blue); color: #fff; }
.button--primary:hover { background: var(--home-blue-hover); }
.button--secondary { border-color: var(--home-line-strong); background: var(--home-surface); color: var(--home-text); }
.button--secondary:hover { border-color: color-mix(in srgb, var(--home-blue) 42%, var(--home-line)); }

.hero__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 24px;
  margin-top: 34px;
  color: var(--home-text-3);
  font-size: 13px;
}

.hero__meta span { display: inline-flex; align-items: center; gap: 7px; }
.hero__meta i { width: 5px; height: 5px; border-radius: 50%; background: var(--home-blue); }

.today-card {
  position: relative;
  padding: 30px;
  border: 1px solid var(--home-line);
  border-radius: 28px;
  background: var(--home-surface);
  box-shadow: var(--home-shadow);
  overflow: hidden;
}

.today-card::before {
  content: "";
  position: absolute;
  inset: 0 0 auto;
  height: 4px;
  background: linear-gradient(90deg, #007aff, #5ac8fa 46%, #30d158);
}

.today-card__top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 20px;
}

.today-card__label { margin: 0; color: var(--home-text-3); font-size: 13px; }
.today-card h2 { margin: 4px 0 0; font-size: 25px; line-height: 1.25; letter-spacing: -0.025em; }
.today-card__badge { padding: 5px 10px; border-radius: 999px; background: var(--home-orange-soft); color: var(--home-orange); font-size: 12px; font-weight: 650; white-space: nowrap; }

.today-list { list-style: none; margin: 26px 0 0; padding: 0; }
.today-list li {
  display: grid;
  grid-template-columns: 28px minmax(0, 1fr) auto;
  gap: 12px;
  align-items: center;
  padding: 14px 0;
  border-top: 1px solid var(--home-line);
}
.today-list__n { color: var(--home-text-3); font-family: var(--home-mono); font-size: 12px; }
.today-list strong { display: block; font-size: 15px; }
.today-list small { display: block; margin-top: 2px; color: var(--home-text-3); font-size: 12px; }
.today-list__tag { color: var(--home-blue); font-size: 12px; font-weight: 650; }

.section {
  padding: clamp(72px, 8vw, 104px) 0;
  border-top: 1px solid var(--home-line);
}

.section--tinted { background: color-mix(in srgb, var(--home-surface-solid) 44%, transparent); }

.section__inner { width: var(--home-shell); margin: 0 auto; }

.section__head {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 32px;
  margin-bottom: 34px;
}

.section__head h2 { margin: 0; font-size: clamp(32px, 4vw, 48px); line-height: 1.1; letter-spacing: -0.045em; }
.section__head p { max-width: 38em; margin: 0; color: var(--home-text-2); font-size: 16px; }

.priority-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
}

.priority-item {
  min-height: 174px;
  padding: 22px;
  border: 1px solid var(--home-line);
  border-radius: 20px;
  background: var(--home-surface-solid);
}

.priority-item__subject { color: var(--home-blue); font-size: 12px; font-weight: 700; letter-spacing: 0.06em; text-transform: uppercase; }
.priority-item h3 { margin: 14px 0 7px; font-size: 20px; line-height: 1.3; letter-spacing: -0.025em; }
.priority-item p { margin: 0; color: var(--home-text-3); font-size: 14px; line-height: 1.55; }

.course-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; }

.course-card {
  --course-accent: var(--home-blue);
  position: relative;
  min-height: 330px;
  display: flex;
  flex-direction: column;
  padding: 30px;
  border: 1px solid var(--home-line);
  border-radius: 26px;
  background: var(--home-surface-solid);
  overflow: hidden;
  transition: border-color 160ms ease, box-shadow 160ms ease, transform 160ms ease;
}

.course-card:hover { transform: translateY(-2px); border-color: color-mix(in srgb, var(--course-accent) 38%, var(--home-line)); box-shadow: var(--home-shadow); }
.course-card::after { content: ""; position: absolute; right: -70px; top: -90px; width: 230px; height: 230px; border-radius: 50%; background: color-mix(in srgb, var(--course-accent) 9%, transparent); pointer-events: none; }
.course-card--ds { --course-accent: #007aff; }
.course-card--os { --course-accent: #248a3d; }
.course-card--co { --course-accent: #c85c00; }
.course-card--net { --course-accent: #7d4bc4; }

.course-card__head { display: flex; align-items: flex-start; justify-content: space-between; gap: 24px; }
.course-card__mark { width: 48px; height: 48px; display: grid; place-items: center; border-radius: 15px; background: color-mix(in srgb, var(--course-accent) 12%, var(--home-surface-solid)); color: var(--course-accent); font-family: var(--home-mono); font-size: 13px; font-weight: 750; }
.course-card__score { color: var(--home-text-3); font-size: 13px; }
.course-card h3 { margin: 28px 0 9px; font-size: clamp(25px, 2.5vw, 34px); line-height: 1.15; letter-spacing: -0.04em; }
.course-card__desc { max-width: 36em; margin: 0; color: var(--home-text-2); font-size: 15px; }
.course-card__topics { display: flex; flex-wrap: wrap; gap: 7px; margin-top: 19px; }
.course-card__topics span { padding: 5px 9px; border-radius: 999px; background: var(--home-bg); color: var(--home-text-3); font-size: 12px; }

.course-card__footer { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 18px; align-items: end; margin-top: auto; padding-top: 30px; }
.course-progress__label { display: flex; align-items: center; justify-content: space-between; gap: 16px; color: var(--home-text-3); font-size: 12px; }
.course-progress__track { height: 5px; margin-top: 8px; border-radius: 999px; background: var(--home-line); overflow: hidden; }
.course-progress__fill { display: block; width: 0; height: 100%; border-radius: inherit; background: var(--course-accent); transition: width 280ms ease; }
.course-card__link { min-height: 44px; display: inline-flex; align-items: center; gap: 7px; color: var(--course-accent); font-size: 14px; font-weight: 650; text-decoration: none; }
.course-card__link::after { content: "›"; font-size: 22px; line-height: 1; transition: transform 140ms ease; }
.course-card__link:hover::after { transform: translateX(2px); }

.learning-loop { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0; border: 1px solid var(--home-line); border-radius: 24px; background: var(--home-surface-solid); overflow: hidden; }
.loop-step { min-height: 210px; padding: 28px; border-right: 1px solid var(--home-line); }
.loop-step:last-child { border-right: 0; }
.loop-step__n { color: var(--home-blue); font-family: var(--home-mono); font-size: 13px; }
.loop-step h3 { margin: 34px 0 8px; font-size: 21px; letter-spacing: -0.025em; }
.loop-step p { margin: 0; color: var(--home-text-3); font-size: 14px; }

.extra-course {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  padding: 24px 28px;
  margin-top: 18px;
  border: 1px solid var(--home-line);
  border-radius: 20px;
  background: var(--home-surface);
}
.extra-course h3 { margin: 0 0 3px; font-size: 19px; }
.extra-course p { margin: 0; color: var(--home-text-3); font-size: 14px; }
.extra-course a { color: var(--home-blue); font-size: 14px; font-weight: 650; text-decoration: none; white-space: nowrap; }

.site-footer { padding: 38px 0 54px; border-top: 1px solid var(--home-line); color: var(--home-text-3); font-size: 13px; }
.site-footer__inner { width: var(--home-shell); margin: 0 auto; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.site-footer p { margin: 0; }
.site-footer a { color: var(--home-blue); text-decoration: none; }

:focus-visible { outline: 3px solid color-mix(in srgb, var(--home-blue) 45%, transparent); outline-offset: 3px; }

@media (max-width: 980px) {
  .site-nav a { display: none; }
  .hero { grid-template-columns: 1fr; gap: 48px; }
  .hero h1 { max-width: 13ch; }
  .today-card { max-width: 680px; }
  .priority-grid, .learning-loop { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .loop-step:nth-child(2) { border-right: 0; }
  .loop-step:nth-child(-n+2) { border-bottom: 1px solid var(--home-line); }
}

@media (max-width: 720px) {
  :root { --home-shell: calc(100% - 32px); }
  body { font-size: 16px; }
  .site-header__inner { min-height: 54px; }
  .brand__text { font-size: 15px; }
  .site-nav { gap: 4px; }
  .appearance-toggle { display: grid; }
  .hero { padding: 60px 0 72px; }
  .hero h1 { font-size: clamp(40px, 12.5vw, 58px); }
  .hero__lede { margin-top: 22px; }
  .hero__actions { margin-top: 28px; }
  .button { width: 100%; }
  .today-card { padding: 24px 20px; border-radius: 22px; }
  .today-list li { grid-template-columns: 24px minmax(0, 1fr); }
  .today-list__tag { display: none; }
  .section { padding: 68px 0; }
  .section__head { display: block; margin-bottom: 28px; }
  .section__head p { margin-top: 14px; }
  .priority-grid, .course-grid, .learning-loop { grid-template-columns: 1fr; }
  .priority-item { min-height: 0; }
  .course-card { min-height: 360px; padding: 24px 20px; border-radius: 22px; }
  .course-card__footer { grid-template-columns: 1fr; }
  .course-card__link { justify-content: flex-start; }
  .loop-step { min-height: 0; border-right: 0; border-bottom: 1px solid var(--home-line); }
  .loop-step:last-child { border-bottom: 0; }
  .loop-step h3 { margin-top: 18px; }
  .extra-course { align-items: flex-start; flex-direction: column; gap: 14px; }
  .site-footer__inner { align-items: flex-start; flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.001ms !important; animation-iteration-count: 1 !important; transition-duration: 0.001ms !important; }
}

@media (prefers-reduced-transparency: reduce) {
  .site-header, .today-card, .extra-course { background: var(--home-surface-solid); -webkit-backdrop-filter: none; backdrop-filter: none; }
}