/* =====================================================================
   TANGENT personal site — theme
   Based on qando design language: white bg, dark ink, fluid clamp sizing,
   768/769 breakpoints, generous whitespace, thin dividers.
   Monochrome palette faithful to qando repo.
===================================================================== */
:root {
  --bg:        #ffffff;
  --paper:     #ffffff;
  --ink:       #262627;
  --ink-soft:  #555;
  --muted:     #f0f0f0;
  --line:      #e6e6e6;
  --accent:    #262627;   /* monochrome, faithful to qando repo palette */
  --accent-dk: #111111;
  --ja_sans:   "Noto Sans SC", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --en_sans:   "Noto Sans SC", "PingFang SC", "Helvetica Neue", Arial, sans-serif;
  --tdu: 0.3s;
  --hh: clamp(0rem, 6.94vw, 6.25rem);
  --maxw: 1280px;
  --pad: clamp(1rem, 5vw, 5rem);
}
@media (max-width: 768px) {
  :root { --hh: clamp(0rem, 20.27vw, 4.75rem); }
}
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--ja_sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: clip;
}
body.wait_splash { overflow: hidden; height: 100vh; }
a { color: inherit; text-decoration: none; transition: color var(--tdu); }
a:hover { color: var(--accent); }
img { max-width: 100%; height: auto; display: block; }
ul { margin: 0; padding: 0; list-style: none; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }

/* ---------- typography helpers ---------- */
.en { font-family: var(--en_sans); }
.sec_head { display: flex; align-items: baseline; gap: 1rem; margin-bottom: clamp(2rem, 5vw, 4rem); }
.sec_head .num { font-family: var(--en_sans); font-size: 0.8rem; color: var(--accent); letter-spacing: 0.1em; }
.sec_head .title { font-size: clamp(1.5rem, 4vw, 2.5rem); font-weight: 700; letter-spacing: 0.02em; }
.sec_head .sub { margin-left: auto; font-size: 0.8rem; color: var(--ink-soft); }
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 var(--pad); }
.section { padding: clamp(4rem, 10vw, 8rem) 0; border-top: 1px solid var(--line); }

/* ---------- header ---------- */
.header { position: fixed; top: 0; left: 0; right: 0; z-index: 100; height: var(--hh); display: flex; align-items: center; padding: 0 var(--pad); color: var(--ink); transition: background var(--tdu), color var(--tdu), box-shadow var(--tdu); }
.header.short { background: var(--paper); box-shadow: 0 1px 0 var(--line); }
.header.opened { background: transparent; box-shadow: none; }
.header.opened, .header.opened .header_nav a, .header.opened .lang_toggle { color: #fff; }
.header_logo { display: inline-flex; align-items: center; height: calc(var(--hh) * 0.6); }
.header_logo img { height: 100%; width: auto; display: block; }
@media (max-width: 768px) {
  .header_logo { height: calc(var(--hh) * 0.5); }
}
.header_nav { margin-left: auto; display: flex; gap: clamp(1rem, 2.5vw, 2.2rem); }
.header_nav a { font-size: 0.82rem; letter-spacing: 0.05em; position: relative; }
.header_nav a::after { content: ""; position: absolute; left: 0; bottom: -4px; width: 0; height: 1px; background: currentColor; transition: width var(--tdu); }
.header_nav a:hover::after { width: 100%; }
.header_btn { display: none; }
.lang_toggle { margin-left: 1.3rem; font-family: var(--en_sans); font-size: 0.74rem; letter-spacing: 0.1em; color: inherit; background: none; border: 1px solid currentColor; border-radius: 999px; padding: 0.28em 0.72em; cursor: pointer; line-height: 1; transition: background var(--tdu), color var(--tdu); }
.lang_toggle:hover { background: var(--ink); color: #fff; }
@media (max-width: 768px) {
  .header_nav { position: fixed; inset: 0; background: var(--ink); flex-direction: column; justify-content: center; align-items: center; gap: 1.5rem; transform: translateY(-100%); transition: transform 0.5s cubic-bezier(0.7,0,0.3,1); }
  .header.opened .header_nav { transform: translateY(0); }
  .header_nav a { font-size: 1.4rem; }
  .header_btn { display: flex; flex-direction: column; gap: 6px; margin-left: auto; width: 28px; }
  .header_btn span { display: block; height: 1px; background: var(--ink); transition: transform var(--tdu), background var(--tdu); }
  .header.opened .header_btn span { background: #fff; }
  .header.opened .header_btn span:nth-child(1) { transform: translateY(3.5px) rotate(45deg); }
  .header.opened .header_btn span:nth-child(2) { transform: translateY(-3.5px) rotate(-45deg); }
  .header.opened .lang_toggle:hover { background: #fff; color: var(--ink); }
}

/* ---------- splash overlay ---------- */
.splash { position: fixed; inset: 0; z-index: 200; background: var(--bg); display: flex; align-items: center; justify-content: center; pointer-events: none; }
.splash_copy { font-family: var(--ja_sans); font-size: clamp(1rem, 2.2vw, 1.4rem); letter-spacing: 0.04em; text-align: center; opacity: 0; }
.splash_logo { font-family: var(--en_sans); font-weight: 700; font-size: clamp(2rem, 6vw, 4rem); letter-spacing: 0.2em; color: var(--accent); opacity: 0; }
body.splash_fase1 .splash_copy { opacity: 1; transition: opacity 0.4s; }
body.splash_fase2 .splash_copy { opacity: 0; transition: opacity 0.3s; }
body.splash_fase2 .splash_logo { opacity: 1; transition: opacity 0.4s 0.05s; }
body.splash_fase3 .splash { background: var(--accent); transition: background 0.3s; }
body.splash_fase3 .splash_logo { color: #fff; }
body:not(.wait_splash) .splash { opacity: 0; transition: opacity 0.4s; }
body.done_splash .splash { display: none; }

/* ---------- firstview ---------- */
.firstview { position: relative; height: 100vh; min-height: 600px; display: flex; align-items: center; justify-content: center; }
.firstview_canvas { position: absolute; inset: 0; width: 100%; height: 100%; }
.firstview_meta { position: absolute; left: var(--pad); bottom: clamp(1.5rem, 4vw, 3rem); right: var(--pad); display: flex; justify-content: space-between; align-items: flex-end; pointer-events: none; }
.firstview_tagline { font-family: var(--en_sans); font-size: clamp(0.85rem, 1.4vw, 1rem); letter-spacing: 0.08em; color: var(--ink-soft); }
.firstview_sub { position: absolute; left: 0; right: 0; top: 62%; text-align: center; font-size: clamp(0.8rem, 1.25vw, 0.95rem); letter-spacing: 0.14em; color: var(--ink-soft); pointer-events: none; }
.firstview_scroll { font-family: var(--en_sans); font-size: 0.75rem; letter-spacing: 0.15em; color: var(--ink-soft); }
.firstview_scroll::after { content: ""; display: block; width: 1px; height: 40px; background: var(--ink-soft); margin: 8px auto 0; animation: scrolldown 1.8s infinite; }
@keyframes scrolldown { 0% { transform: scaleY(0); transform-origin: top; } 50% { transform: scaleY(1); transform-origin: top; } 51% { transform-origin: bottom; } 100% { transform: scaleY(0); transform-origin: bottom; } }
body:not(.done_splash) .firstview_meta,
body:not(.done_splash) .firstview_sub { opacity: 0; }

/* ---------- about ---------- */
.about_grid { display: grid; grid-template-columns: minmax(0, 0.8fr) 1fr; gap: clamp(2rem, 6vw, 5rem); align-items: start; }
.about_portrait_wrap { position: sticky; top: 100px; }
.about_portrait { width: 100%; aspect-ratio: 3/4; object-fit: cover; border-radius: 4px; display: block; }
.about_copy h2 { font-size: clamp(1.6rem, 4vw, 2.8rem); line-height: 1.35; margin: 0 0 1.5rem; }
.about_copy p { color: var(--ink-soft); margin: 0 0 1rem; line-height: 1.7; }
.about_tags { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 1.5rem; }
.about_tags span { font-size: 0.78rem; padding: 0.4rem 0.9rem; border: 1px solid var(--line); border-radius: 999px; color: var(--ink-soft); }
.about_meta { font-size: 0.85rem; margin-top: 2.5rem; padding-top: 1.5rem; border-top: 1px solid var(--line); }
.about_meta dt { font-family: var(--en_sans); color: var(--accent); margin-top: 1.2rem; letter-spacing: 0.08em; }
.about_meta dt:first-of-type { margin-top: 0; }
.about_meta dd { margin: 0.2rem 0 0; color: var(--ink-soft); }
@media (max-width: 768px) { .about_grid { grid-template-columns: 1fr; } .about_portrait_wrap { position: static; max-width: 320px; margin: 0 auto 2rem; } }

/* ---------- ai builder (swiper cards) ---------- */
.ai_carousel { overflow: visible; }
.ai_card { background: var(--muted); border-radius: 4px; overflow: hidden; transition: transform var(--tdu); }
.ai_card:hover { transform: translateY(-6px); }
.ai_card_thumb { aspect-ratio: 16/10; background: var(--line); }
.thumb_placeholder { display: flex; align-items: center; justify-content: center; height: 100%; font-size: 0.78rem; color: #999; letter-spacing: 0.1em; }
.ai_card_thumb img { width: 100%; height: 100%; object-fit: cover; }
.ai_card_body { padding: 1.2rem 1.4rem 1.6rem; }
.ai_card_tag { font-family: var(--en_sans); font-size: 0.72rem; color: var(--accent); letter-spacing: 0.1em; }
.ai_card_title { font-size: 1.15rem; font-weight: 700; margin: 0.4rem 0; line-height: 1.3; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; min-height: 3em; }
.ai_card_desc { font-size: 0.85rem; color: var(--ink-soft); line-height: 1.5; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; min-height: 4.5em; }
.ai_card_meta { display: flex; gap: 1rem; margin-top: 0.8rem; font-size: 0.72rem; color: var(--ink-soft); }
.ai_nav { display: flex; gap: clamp(0.8rem, 1.2vw, 1.2rem); justify-content: flex-end; margin-top: clamp(1rem, 2vw, 1.8rem); }
.ai_arrow { position: relative; width: clamp(2.6rem, 3.5vw, 3.4rem); height: 2.4rem; display: inline-flex; align-items: center; justify-content: center; background: none; border: 0; cursor: pointer; transition: opacity var(--tdu); }
.ai_arrow svg { width: clamp(1.5rem, 2.2vw, 1.9rem); height: auto; fill: var(--ink); display: block; }
.ai_arrow_prev svg { transform: scaleX(-1); }
.ai_arrow:hover { opacity: .45; }
.ai_card_link { color: var(--ink-soft); text-decoration: none; transition: color var(--tdu); letter-spacing: 0.03em; }
.ai_card_link:hover { color: var(--ink); }
.vh { position: absolute !important; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }
@media (max-width: 768px) { .ai_nav { justify-content: center; } }

/* ---------- AI subpage ---------- */
.ai_hero { padding: calc(var(--hh) + clamp(2rem, 6vw, 4rem)) 0 clamp(1.5rem, 4vw, 3rem); }
.ai_hero h1 { font-size: clamp(2.5rem, 8vw, 5rem); font-weight: 700; margin: 0; line-height: 1; }
.ai_hero_sub { color: var(--ink-soft); margin: 1rem 0 0; font-size: clamp(0.95rem, 1.6vw, 1.05rem); max-width: 48ch; }
.ai_hero_count { font-family: var(--en_sans); color: var(--ink-soft); margin: 0.8rem 0 0; font-size: 0.9rem; }
.ai_grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: clamp(1.2rem, 2.5vw, 2rem); }
@media (max-width: 600px) { .ai_grid { grid-template-columns: 1fr; } }

/* ---------- section "view all" link (homepage photo / articles) ---------- */
.viewall_link { font-size: 0.8rem; color: var(--ink-soft); letter-spacing: 0.05em; text-decoration: none; transition: color var(--tdu); white-space: nowrap; align-self: center; }
.viewall_link:hover { color: var(--ink); }

/* ---------- photography ---------- */
.photo_tools { display: flex; gap: 1rem; align-items: center; flex-wrap: wrap; margin-bottom: 2rem; }
.photo_view_toggle { display: flex; border: 1px solid var(--line); border-radius: 999px; overflow: hidden; }
.photo_view_toggle button { padding: 0.5rem 1.2rem; font-size: 0.8rem; transition: all var(--tdu); }
.photo_view_toggle button.active { background: var(--ink); color: #fff; }
.photo_filters { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.photo_filters button { font-size: 0.78rem; padding: 0.4rem 0.9rem; border: 1px solid var(--line); border-radius: 999px; color: var(--ink-soft); transition: all var(--tdu); }
.photo_filters button.active { border-color: var(--ink); color: var(--ink); background: var(--muted); }

/* photography landing (homepage category cards) */
.photo_landing { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: clamp(1rem, 2vw, 1.6rem); }
@media (max-width: 480px) { .photo_landing { grid-template-columns: 1fr; } }
.photo_card { display: block; position: relative; overflow: hidden; border-radius: 4px; background: var(--muted); transition: transform var(--tdu); }
.photo_card:hover { transform: translateY(-6px); }
.photo_card_thumb { aspect-ratio: 4/5; overflow: hidden; }
.photo_card_thumb img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.7s, opacity .4s ease; opacity: 0; }
.photo_card_thumb img.loaded { opacity: 1; }
.photo_card:hover .photo_card_thumb img { transform: scale(1.06); }
.photo_card_body { position: absolute; left: 0; right: 0; bottom: 0; padding: 1.2rem; color: #fff; background: linear-gradient(to top, rgba(0,0,0,0.75), transparent); }
.photo_card_num { font-size: 0.72rem; letter-spacing: 0.1em; opacity: 0.8; }
.photo_card_title { font-size: 1.25rem; font-weight: 700; margin: 0.2rem 0 0.3rem; }
.photo_card_title .en { font-size: 0.7rem; opacity: 0.7; font-weight: 400; margin-left: 0.4rem; }
.photo_card_meta { font-size: 0.74rem; opacity: 0.85; margin: 0; }
.photo_card_link { display: inline-block; margin-top: 0.5rem; font-size: 0.74rem; letter-spacing: 0.08em; }

/* photography subpage hero */
.photo_hero { padding: calc(var(--hh) + clamp(2rem, 6vw, 4rem)) 0 clamp(1.5rem, 4vw, 3rem); }
.back_link { display: inline-block; font-size: 0.8rem; color: var(--ink-soft); margin-bottom: 1.5rem; letter-spacing: 0.05em; }
.back_link:hover { color: var(--ink); }
.photo_hero h1 { font-size: clamp(2.5rem, 8vw, 5rem); font-weight: 700; margin: 0; line-height: 1; }
.photo_hero_count { font-family: var(--en_sans); color: var(--ink-soft); margin: 0.8rem 0 0; font-size: 0.9rem; }
.photo_grid { columns: 3; column-gap: clamp(0.5rem, 1.5vw, 1.2rem); }
@media (max-width: 900px) { .photo_grid { columns: 2; } }
@media (max-width: 560px) { .photo_grid { columns: 1; } }
.photo_item { break-inside: avoid; margin-bottom: clamp(0.5rem, 1.5vw, 1.2rem); position: relative; cursor: pointer; overflow: hidden; border-radius: 2px; background: var(--muted); min-height: 180px; }
.photo_item img { width: 100%; transition: transform 0.6s, opacity .4s ease; filter: grayscale(0); opacity: 0; }
.photo_item img.loaded { opacity: 1; }
.photo_item.skeleton::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.55), transparent);
  transform: translateX(-100%);
  animation: photo-skel 1.4s infinite linear;
}
@keyframes photo-skel { 100% { transform: translateX(100%); } }
.photo_sentinel { height: 1px; width: 100%; }
.photo_item:hover img { transform: scale(1.04); }
.photo_item .photo_info { position: absolute; left: 0.8rem; bottom: 0.8rem; font-size: 0.72rem; color: #fff; text-shadow: 0 1px 4px rgba(0,0,0,0.6); opacity: 0; transition: opacity var(--tdu); }
.photo_item:hover .photo_info { opacity: 1; }
.photo_time_group { margin-bottom: 2.5rem; }
.photo_time_group h3 { font-family: var(--en_sans); font-size: 1.2rem; margin: 0 0 1rem; padding-bottom: 0.5rem; border-bottom: 1px solid var(--line); }
.photo_grid.hidden { display: none; }
.photo_time_view.hidden { display: none; }

/* lightbox */
.lightbox { position: fixed; inset: 0; z-index: 300; background: rgba(0,0,0,0.92); display: flex; align-items: center; justify-content: center; opacity: 0; pointer-events: none; transition: opacity var(--tdu); }
.lightbox.open { opacity: 1; pointer-events: auto; }
.lightbox img { max-width: 90vw; max-height: 85vh; object-fit: contain; }
.lightbox_close { position: absolute; top: 1.5rem; right: 1.5rem; color: #fff; font-size: 2rem; line-height: 1; }
.lightbox_nav { position: absolute; top: 50%; transform: translateY(-50%); color: #fff; font-size: 2.4rem; padding: 1rem; }
.lightbox_nav.prev { left: 1rem; } .lightbox_nav.next { right: 1rem; }
.lightbox_caption { position: absolute; bottom: 1.5rem; left: 0; right: 0; text-align: center; color: #fff; font-size: 0.85rem; }

/* ---------- experiences (timeline) ---------- */
.exp_list { position: relative; }
.exp_list::before { content: ""; position: absolute; left: 8px; top: 0; bottom: 0; width: 1px; background: var(--line); }
.exp_item { position: relative; padding: 0 0 2.5rem 2.5rem; }
.exp_item::before { content: ""; position: absolute; left: 3px; top: 6px; width: 11px; height: 11px; border-radius: 50%; background: var(--accent); }
.exp_date { font-family: var(--en_sans); font-size: 0.8rem; color: var(--accent); letter-spacing: 0.05em; }
.exp_title { font-size: 1.15rem; font-weight: 700; margin: 0.3rem 0 0.5rem; }
.exp_desc { font-size: 0.88rem; color: var(--ink-soft); }
.exp_role { display: inline-block; font-size: 0.72rem; padding: 0.2rem 0.6rem; background: var(--muted); border-radius: 3px; margin-top: 0.5rem; }

/* ---------- articles / blog ---------- */
.blog_list { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.5rem; border-top: 1px solid var(--line); padding-top: 1.5rem; }
.blog_item { display: flex; flex-direction: column; gap: 0.7rem; padding: 1.5rem; border: 1px solid var(--line); border-radius: 6px; cursor: pointer; transition: border-color var(--tdu), transform var(--tdu); background: var(--paper); }
.blog_item:hover { border-color: var(--ink); transform: translateY(-2px); }
.blog_item_head { display: flex; align-items: center; gap: 0.8rem; flex-wrap: wrap; }
.blog_item_date { font-family: var(--en_sans); font-size: 0.74rem; letter-spacing: 0.08em; color: var(--ink-soft); }
.blog_item_tags { display: flex; gap: 0.4rem; flex-wrap: wrap; }
.blog_item_tags span { font-family: var(--en_sans); font-size: 0.66rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink-soft); border: 1px solid var(--line); border-radius: 999px; padding: 0.18em 0.6em; }
.blog_item_title { font-size: 1.2rem; font-weight: 600; line-height: 1.35; }
.blog_item_excerpt { font-size: 0.92rem; color: var(--ink-soft); line-height: 1.6; flex: 1; }
.blog_item_link { font-family: var(--en_sans); font-size: 0.78rem; letter-spacing: 0.06em; color: var(--accent); }
@media (max-width: 700px) { .blog_list { grid-template-columns: 1fr; } }

/* ---------- article page (article.html) ---------- */
.article { padding-top: clamp(5rem, 12vh, 8rem); padding-bottom: 6rem; }
.article_inner { max-width: 720px; margin: 0 auto; padding: 0 var(--pad); }
.article_back { display: inline-block; font-family: var(--en_sans); font-size: 0.8rem; letter-spacing: 0.06em; color: var(--ink-soft); margin-bottom: 2.5rem; transition: color var(--tdu); }
.article_back:hover { color: var(--accent); }
.article_meta { display: flex; align-items: center; gap: 0.8rem; flex-wrap: wrap; margin-bottom: 0.8rem; }
.article_meta .en { font-size: 0.78rem; letter-spacing: 0.08em; color: var(--ink-soft); }
.article_tags { display: inline-flex; gap: 0.4rem; flex-wrap: wrap; }
.article_tags span { font-family: var(--en_sans); font-size: 0.66rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink-soft); border: 1px solid var(--line); border-radius: 999px; padding: 0.18em 0.6em; }
.article_title { font-size: clamp(1.8rem, 4.5vw, 2.6rem); font-weight: 700; line-height: 1.25; margin: 0 0 2rem; }
.article_content { font-size: 1.02rem; line-height: 1.9; color: var(--ink); }
.article_content p { margin: 0 0 1.3em; }
.article_content p:last-child { margin-bottom: 0; }
.article_notfound { padding: 4rem 0; text-align: center; color: var(--ink-soft); }

/* ---------- contact ---------- */
.contact { text-align: center; }
.contact h2 { font-size: clamp(2rem, 7vw, 4.5rem); font-weight: 700; line-height: 1.2; margin: 0 0 1.5rem; }
.contact h2 em { font-style: normal; color: var(--accent); }
.contact .email { display: inline-block; font-family: var(--en_sans); font-size: clamp(1rem, 2vw, 1.3rem); padding: 1rem 2.5rem; border: 1px solid var(--ink); border-radius: 999px; margin-top: 1rem; transition: all var(--tdu); }
.contact .email:hover { background: var(--ink); color: #fff; }
.contact_links { display: flex; gap: 1.5rem; justify-content: center; margin-top: 2rem; font-size: 0.85rem; }

/* ---------- footer ---------- */
.footer { padding: 2.5rem 0; border-top: 1px solid var(--line); }
.footer_inner { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 1rem; }
.footer_copy { font-family: var(--en_sans); font-size: 0.78rem; color: var(--ink-soft); }
.footer_nav { display: flex; gap: 1.5rem; font-size: 0.78rem; }

/* ---------- mousestalker (removed) ---------- */
/* ---------- reveal on scroll ---------- */
.reveal { opacity: 0; transform: translateY(30px); transition: opacity 0.8s, transform 0.8s; }
.reveal.in { opacity: 1; transform: none; }