/*
  张开 Kai Zhang 个人网站
  ============================================================
  这是全站唯一的样式文件。通常你只需要修改 HTML 文字和图片。

  如果要微调视觉，最常修改的是下方 :root 中的：
  --paper      页面背景
  --ink        正文颜色
  --brick      强调色
  --moss       内页标题背景
*/

:root {
  --paper: #f1efe8;
  --paper-deep: #e4dfd3;
  --paper-bright: #f8f6ef;
  --ink: #181914;
  --ink-soft: #55574e;
  --moss: #202821;
  --moss-deep: #11150f;
  --brick: #984433;
  --brick-dark: #703125;
  --rule: rgba(24, 25, 20, 0.2);

  --serif: "Songti SC", "Noto Serif CJK SC", "Source Han Serif SC",
    "STSong", "SimSun", Georgia, serif;
  --sans: "PingFang SC", "Noto Sans CJK SC", "Source Han Sans SC",
    "Microsoft YaHei", Arial, sans-serif;
  --display: "Bodoni 72", Didot, "Times New Roman", var(--serif);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 72px;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.68;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

/* 很轻的纸张纹理 */
body::before {
  position: fixed;
  inset: 0;
  z-index: 9999;
  pointer-events: none;
  content: "";
  opacity: 0.032;
  background-image: repeating-linear-gradient(
    0deg,
    rgba(0, 0, 0, 0.12) 0,
    rgba(0, 0, 0, 0.12) 1px,
    transparent 1px,
    transparent 3px
  );
  mix-blend-mode: multiply;
}

::selection {
  color: var(--paper-bright);
  background: var(--brick);
}

a {
  color: inherit;
  text-decoration: none;
}

button {
  color: inherit;
}

p,
h1,
h2,
h3,
figure {
  margin: 0;
}

ul,
ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

img {
  display: block;
  max-width: 100%;
}

/*
  中文默认显示。
  script.js 会把 data-language 从 zh 改为 en。
*/
.lang.en {
  display: none;
}

html[data-language="en"] .lang.zh {
  display: none !important;
}

html[data-language="en"] .lang.en {
  display: revert;
}

.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 1000;
  padding: 7px 11px;
  color: var(--paper-bright);
  background: var(--ink);
  transform: translateY(-180%);
}

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

/* ==========================================================
   顶部导航
   ========================================================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  display: grid;
  grid-template-columns: minmax(230px, 1fr) auto minmax(95px, 1fr);
  align-items: center;
  min-height: 72px;
  padding: 0 clamp(24px, 4vw, 66px);
  border-bottom: 1px solid var(--rule);
  background: rgba(241, 239, 232, 0.94);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
}

.wordmark {
  display: flex;
  align-items: center;
  width: fit-content;
  line-height: 1;
}

.wordmark-cn {
  font-family: var(--serif);
  font-size: 1.28rem;
  font-weight: 700;
  letter-spacing: 0.1em;
}

.wordmark-rule {
  width: 27px;
  height: 1px;
  margin: 0 11px;
  background: var(--ink);
}

.wordmark-en {
  font-family: var(--display);
  font-size: 0.84rem;
  font-style: italic;
}

.main-nav {
  display: flex;
  gap: clamp(22px, 2.7vw, 42px);
}

.main-nav a {
  position: relative;
  padding: 8px 0;
  color: var(--ink-soft);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  white-space: nowrap;
}

.main-nav a::after {
  position: absolute;
  right: 0;
  bottom: 1px;
  left: 0;
  height: 1px;
  content: "";
  background: var(--brick);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 220ms ease;
}

.main-nav a:hover,
.main-nav a:focus-visible,
.main-nav a.is-active {
  color: var(--ink);
}

.main-nav a:hover::after,
.main-nav a:focus-visible::after,
.main-nav a.is-active::after {
  transform: scaleX(1);
  transform-origin: left;
}

.language-button {
  justify-self: end;
  padding: 8px 0;
  border: 0;
  background: transparent;
  cursor: pointer;
  font-family: var(--sans);
  font-size: 0.72rem;
  letter-spacing: 0.07em;
}

.language-button span {
  opacity: 0.36;
}

.language-button i {
  padding: 0 6px;
  font-style: normal;
  opacity: 0.3;
}

html[data-language="zh"] .language-choice[data-choice="zh"],
html[data-language="en"] .language-choice[data-choice="en"] {
  opacity: 1;
}

.menu-button {
  display: none;
}

/* ==========================================================
   首页
   ========================================================== */

.home-page {
  display: grid;
  grid-template-columns: minmax(570px, 1.08fr) minmax(440px, 0.92fr);
  gap: clamp(46px, 5.5vw, 88px);
  min-height: calc(100svh - 72px);
  padding: clamp(30px, 3.6vw, 52px) clamp(28px, 5vw, 78px);
  border-bottom: 1px solid var(--rule);
}

.home-about {
  align-self: center;
}

.home-portrait {
  width: clamp(145px, 13vw, 178px);
  margin-bottom: 23px;
}

.home-portrait .home-image-frame {
  aspect-ratio: 4 / 5;
}

.home-image-frame {
  position: relative;
  overflow: hidden;
  background: var(--moss);
}

.home-image-frame > img,
.portrait-placeholder {
  width: 100%;
  height: 100%;
}

.home-image-frame > img {
  position: relative;
  z-index: 2;
  object-fit: cover;
  filter: saturate(0.76) contrast(1.02);
  transition: filter 350ms ease, transform 650ms ease;
}

.home-image-frame:hover > img {
  filter: saturate(0.92) contrast(1.01);
  transform: scale(1.02);
}

.portrait-image > img {
  position: absolute;
  inset: 0;
}

/* 未放入个人照片时显示的占位框 */
.portrait-placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--paper);
  background:
    radial-gradient(circle at 60% 28%, rgba(255, 255, 255, 0.08), transparent 22%),
    linear-gradient(150deg, #34453b, #111813);
}

.portrait-placeholder::before {
  position: absolute;
  inset: 14px;
  border: 1px solid rgba(255, 255, 255, 0.2);
  content: "";
}

.portrait-placeholder span {
  font-family: var(--display);
  font-size: 1rem;
  font-style: italic;
  letter-spacing: 0.18em;
}

.portrait-placeholder small {
  margin-top: 8px;
  font-size: 0.5rem;
  letter-spacing: 0.25em;
  opacity: 0.55;
}

.home-about-copy {
  max-width: 950px;
}

.home-about-copy p {
  color: var(--ink-soft);
  font-family: var(--serif);
  font-size: clamp(0.92rem, 1.05vw, 1.02rem);
  line-height: 1.78;
  text-align: justify;
}

.home-about-copy p + p {
  margin-top: 12px;
}

.home-details {
  display: grid;
  grid-template-columns: minmax(0, 1.45fr) minmax(180px, 0.55fr);
  gap: clamp(32px, 4vw, 65px);
  margin-top: 25px;
  padding-top: 20px;
  border-top: 1px solid var(--rule);
}

.home-details h2 {
  margin-bottom: 9px;
  color: var(--brick);
  font-family: var(--serif);
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.06em;
}

.compact-list li {
  display: grid;
  grid-template-columns: 88px 1fr;
  gap: 12px;
  padding: 5px 0;
  border-bottom: 1px solid var(--rule);
  font-size: 0.75rem;
  line-height: 1.5;
}

.compact-list time,
.compact-language-list em {
  color: var(--ink-soft);
  font-family: var(--display);
  font-style: italic;
}

.compact-language-list li {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  padding: 5px 0;
  border-bottom: 1px solid var(--rule);
  font-size: 0.75rem;
  line-height: 1.5;
}

.home-roman {
  align-self: center;
}

.home-roman .home-image-frame {
  height: min(710px, calc(100svh - 138px));
  min-height: 540px;
}

.roman-image > img {
  object-position: 59% center;
}

.image-label {
  position: absolute;
  right: 12px;
  bottom: 11px;
  left: 12px;
  z-index: 3;
  padding-top: 7px;
  border-top: 1px solid rgba(255, 255, 255, 0.48);
  color: var(--paper-bright);
  font-size: 0.48rem;
  letter-spacing: 0.16em;
}

.home-portrait figcaption,
.home-roman figcaption {
  min-height: 39px;
  padding-top: 10px;
  border-bottom: 1px solid var(--ink);
  font-size: 0.66rem;
  letter-spacing: 0.04em;
}

.home-portrait figcaption a,
.home-roman figcaption a,
.pending-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.home-portrait figcaption a span,
.home-roman figcaption a span {
  color: var(--brick);
}

.pending-link {
  color: var(--ink-soft);
}

/* ==========================================================
   内页公共标题
   标题区刻意保持紧凑，进入页面即可看到正文。
   ========================================================== */

.page-masthead {
  display: grid;
  grid-template-columns: minmax(130px, 0.28fr) 1fr;
  align-items: center;
  min-height: 148px;
  padding: 27px clamp(28px, 6vw, 94px);
  color: var(--paper-bright);
  background:
    linear-gradient(125deg, rgba(255, 255, 255, 0.025), transparent 48%),
    var(--moss);
}

.page-index {
  display: flex;
  align-items: center;
  gap: 12px;
  font-family: var(--display);
  font-size: 0.61rem;
  letter-spacing: 0.16em;
  opacity: 0.65;
}

.page-index span {
  width: 34px;
  height: 1px;
  background: currentColor;
}

.page-masthead h1 {
  font-family: var(--serif);
  font-size: clamp(2.35rem, 4.1vw, 3.8rem);
  font-weight: 400;
  letter-spacing: -0.035em;
  line-height: 1;
}

.content-page {
  padding: clamp(40px, 5vw, 62px) clamp(28px, 6vw, 94px);
}

/* ==========================================================
   研究
   ========================================================== */

.research-page {
  padding-top: clamp(36px, 4vw, 52px);
}

.research-list-section {
  max-width: 1320px;
  margin-left: auto;
}

.research-list-section + .research-list-section {
  margin-top: clamp(46px, 5vw, 68px);
}

.list-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--ink);
}

.list-heading h2 {
  font-family: var(--serif);
  font-size: clamp(1.45rem, 2.2vw, 2.25rem);
  font-weight: 400;
}

.list-heading > span {
  color: var(--brick);
  font-family: var(--display);
  font-size: 0.7rem;
}

.publication-list li {
  display: grid;
  grid-template-columns: 40px 72px 1fr;
  gap: 15px;
  align-items: start;
  padding: 17px 0;
  border-bottom: 1px solid var(--rule);
}

.entry-index {
  color: var(--brick);
  font-family: var(--display);
  font-size: 0.61rem;
}

.publication-list time,
.conference-list time {
  font-family: var(--display);
  font-size: 0.86rem;
  font-style: italic;
}

.publication-list p,
.conference-list p {
  max-width: 1080px;
  font-family: var(--serif);
  font-size: 0.96rem;
  line-height: 1.64;
}

.conference-list li {
  display: grid;
  grid-template-columns: 95px 1fr;
  gap: 26px;
  padding: 16px 0;
  border-bottom: 1px solid var(--rule);
}

/* ==========================================================
   教学
   ========================================================== */

.simple-page {
  min-height: 42vh;
}

.simple-page > p {
  max-width: 980px;
  font-family: var(--serif);
  font-size: 1.02rem;
  line-height: 1.75;
}

/* ==========================================================
   研究之外
   ========================================================== */

.beyond-page {
  display: grid;
  grid-template-columns: 1.05fr 0.9fr 1.05fr;
  padding-top: clamp(38px, 4vw, 52px);
  padding-bottom: clamp(44px, 5vw, 64px);
}

.beyond-page article {
  min-height: 290px;
  padding: 26px clamp(22px, 2.8vw, 40px);
  border-top: 1px solid var(--ink);
  border-bottom: 1px solid var(--ink);
}

.beyond-page article + article {
  border-left: 1px solid var(--rule);
}

.beyond-page article:first-child {
  color: var(--paper-bright);
  background: var(--brick-dark);
}

.beyond-index {
  color: var(--brick);
  font-family: var(--display);
  font-size: 0.64rem;
  letter-spacing: 0.13em;
}

.beyond-page article:first-child .beyond-index {
  color: rgba(255, 255, 255, 0.65);
}

.beyond-page h2 {
  margin: 27px 0 13px;
  font-family: var(--serif);
  font-size: clamp(1.45rem, 2.2vw, 2.2rem);
  font-weight: 400;
}

.beyond-page p {
  color: var(--ink-soft);
  font-family: var(--serif);
  font-size: 0.92rem;
  line-height: 1.68;
}

.beyond-page article:first-child p {
  color: rgba(255, 255, 255, 0.78);
}

.beyond-page article > a {
  display: inline-block;
  margin-top: 20px;
  padding-bottom: 2px;
  border-bottom: 1px solid var(--ink);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.beyond-page article > a span {
  margin-left: 7px;
  color: var(--brick);
}

.blog-card h2 {
  margin-bottom: 7px;
}

.blog-list li {
  border-bottom: 1px solid var(--rule);
}

.blog-list a,
.blog-empty {
  display: grid;
  grid-template-columns: 42px 1fr auto;
  gap: 9px;
  align-items: center;
  min-height: 43px;
  font-family: var(--serif);
  font-size: 0.78rem;
  line-height: 1.45;
}

.blog-list time {
  color: var(--brick);
  font-family: var(--display);
  font-size: 0.68rem;
  font-style: italic;
}

.blog-list a > span:last-child {
  color: var(--brick);
}

.blog-empty {
  color: var(--ink-soft);
  opacity: 0.72;
}

/* ==========================================================
   页脚
   ========================================================== */

.site-footer {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 32px;
  padding: 40px clamp(28px, 6vw, 94px) 20px;
  color: var(--paper);
  background: var(--moss-deep);
}

.footer-identity > span {
  font-family: var(--serif);
  font-size: 2.1rem;
  letter-spacing: 0.07em;
}

.footer-identity p {
  font-family: var(--display);
  font-size: 0.88rem;
  font-style: italic;
}

.footer-email {
  align-self: start;
  margin-top: 10px;
  padding-bottom: 2px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.38);
  font-size: 0.72rem;
}

.footer-bottom {
  display: flex;
  grid-column: 1 / -1;
  align-items: center;
  justify-content: space-between;
  margin-top: 16px;
  padding-top: 15px;
  border-top: 1px solid rgba(255, 255, 255, 0.15);
  font-size: 0.59rem;
  letter-spacing: 0.07em;
  opacity: 0.62;
}

/*
  英文统一字号与行距，避免局部忽大忽小。
*/
html[data-language="en"] .home-about-copy p,
html[data-language="en"] .publication-list p,
html[data-language="en"] .conference-list p,
html[data-language="en"] .simple-page > p,
html[data-language="en"] .beyond-page p {
  font-size: 0.96rem;
  line-height: 1.68;
}

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--brick);
  outline-offset: 4px;
}

/* ==========================================================
   平板
   ========================================================== */

@media (max-width: 1120px) {
  .site-header {
    grid-template-columns: 1fr auto;
  }

  .main-nav {
    position: absolute;
    top: 71px;
    right: 0;
    left: 0;
    display: none;
    flex-direction: column;
    gap: 0;
    padding: 14px clamp(24px, 4vw, 66px) 23px;
    border-bottom: 1px solid var(--rule);
    background: var(--paper);
  }

  .main-nav.is-open {
    display: flex;
  }

  .main-nav a {
    padding: 12px 0;
    border-bottom: 1px solid var(--rule);
  }

  .menu-button {
    display: flex;
    align-items: center;
    gap: 11px;
    justify-self: end;
    padding: 8px 0;
    border: 0;
    background: transparent;
    cursor: pointer;
    font-family: var(--sans);
    font-size: 0.68rem;
    letter-spacing: 0.12em;
  }

  .menu-button i {
    width: 17px;
    height: 8px;
    border-top: 1px solid currentColor;
    border-bottom: 1px solid currentColor;
  }

  .language-button {
    position: absolute;
    right: clamp(90px, 13vw, 140px);
  }

  .home-page {
    grid-template-columns: minmax(0, 1.06fr) minmax(365px, 0.94fr);
    gap: 38px;
    padding-right: 32px;
    padding-left: 32px;
  }

  .home-details {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .beyond-page {
    grid-template-columns: 1fr 1fr;
  }

  .beyond-page article:first-child {
    grid-column: 1 / -1;
  }

  .beyond-page article:nth-child(2) {
    border-left: 0;
  }
}

@media (max-width: 860px) {
  .home-page {
    grid-template-columns: 1fr;
    gap: 44px;
    padding: 52px 28px 62px;
  }

  .home-details {
    grid-template-columns: 1.35fr 0.65fr;
  }

  .home-roman {
    width: min(100%, 680px);
  }

  .home-roman .home-image-frame {
    height: auto;
    min-height: 0;
    aspect-ratio: 4 / 3;
  }

  .home-roman .roman-image > img {
    object-position: center;
  }
}

/* ==========================================================
   手机
   ========================================================== */

@media (max-width: 620px) {
  html {
    scroll-padding-top: 64px;
  }

  body {
    font-size: 15px;
  }

  .site-header {
    min-height: 64px;
    padding: 0 19px;
  }

  .wordmark-cn {
    font-size: 1.18rem;
  }

  .wordmark-rule {
    width: 16px;
    margin: 0 8px;
  }

  .wordmark-en {
    font-size: 0.71rem;
  }

  .main-nav {
    top: 63px;
    padding-right: 19px;
    padding-left: 19px;
  }

  .menu-button span {
    display: none;
  }

  .language-button {
    right: 55px;
  }

  .home-page {
    gap: 38px;
    min-height: 0;
    padding: 42px 20px 52px;
  }

  .home-about-copy p,
  html[data-language="en"] .home-about-copy p {
    font-size: 0.94rem;
    line-height: 1.72;
    text-align: left;
  }

  .home-details {
    grid-template-columns: 1fr;
    gap: 22px;
  }

  .compact-list li {
    grid-template-columns: 78px 1fr;
  }

  .home-portrait {
    width: min(44vw, 170px);
    margin-bottom: 22px;
  }

  .home-portrait figcaption,
  .home-roman figcaption {
    overflow-wrap: anywhere;
    font-size: 0.59rem;
  }

  .image-label {
    font-size: 0.4rem;
    letter-spacing: 0.1em;
  }

  .page-masthead {
    grid-template-columns: 1fr;
    gap: 16px;
    min-height: 0;
    padding: 24px 20px 27px;
  }

  .page-masthead h1 {
    font-size: clamp(2.25rem, 11vw, 3.2rem);
  }

  .content-page {
    padding: 36px 20px 48px;
  }

  .research-list-section + .research-list-section {
    margin-top: 48px;
  }

  .publication-list li {
    grid-template-columns: 31px 1fr;
    gap: 6px 12px;
    padding: 17px 0;
  }

  .publication-list time {
    grid-column: 2;
    grid-row: 1;
  }

  .publication-list p {
    grid-column: 1 / -1;
    margin-top: 5px;
  }

  .conference-list li {
    grid-template-columns: 62px 1fr;
    gap: 15px;
  }

  .beyond-page {
    grid-template-columns: 1fr;
    padding: 36px 20px 48px;
  }

  .beyond-page article:first-child {
    grid-column: auto;
  }

  .beyond-page article {
    min-height: 0;
    padding: 24px 22px 29px;
  }

  .beyond-page article + article {
    border-top: 0;
    border-left: 0;
  }

  .site-footer {
    grid-template-columns: 1fr;
    gap: 20px;
    padding: 36px 20px 19px;
  }

  .footer-email {
    justify-self: start;
    margin-top: 0;
  }

  .footer-bottom {
    grid-column: 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}