:root {
  --color-bg: #1a1b26;
  --color-surface: #222336;
  --color-text: #c0caf5;
  --color-text-soft: #a9b2d8;
  --color-muted: #737aa2;
  --color-accent: #7aa2f7;
  --color-accent-rgb: 122, 162, 247;
  --color-accent-dim: rgba(122, 162, 247, 0.12);
  --color-border: #2e3150;
  --color-green: #9ece6a;
  --color-purple: #bb9af7;
  --color-yellow: #e0af68;
  --color-cyan: #7dcfff;
  --color-heading: #f2f4fc;
  --color-tagline: #b4bce0;
  --glow-alpha: 0.22;
  --max-width: 760px;
  --font-mono: "JetBrains Mono", "Fira Code", "SF Mono", "Cascadia Code", Consolas, monospace;
}

/* ── Morning theme ── */
[data-theme="morning"] {
  --color-bg: #f4f7fc;
  --color-surface: #ffffff;
  --color-text: #2c3654;
  --color-text-soft: #4b5677;
  --color-muted: #7f8aa8;
  --color-accent: #2e7de9;
  --color-accent-rgb: 46, 125, 233;
  --color-accent-dim: rgba(46, 125, 233, 0.10);
  --color-border: #d6deec;
  --color-green: #4e8a2a;
  --color-purple: #7847bd;
  --color-yellow: #b07a1c;
  --color-cyan: #0e7fa6;
  --color-heading: #1c2540;
  --color-tagline: #4b5677;
  --color-bird: #3a4766;
  --glow-alpha: 0.08;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* ── Shooting stars ── */
.container { position: relative; z-index: 1; }

.shooting-star {
  position: absolute;
  top: 0;
  left: 0;
  height: 1.5px;
  width: var(--len, 110px);
  background: linear-gradient(90deg,
    rgba(192, 202, 245, 0) 0%,
    rgba(122, 162, 247, 0.35) 60%,
    rgba(255, 255, 255, 0.7) 100%);
  border-radius: 999px;
  transform-origin: left center;
  filter: drop-shadow(0 0 4px rgba(122, 162, 247, 0.4));
  pointer-events: none;
  z-index: 0;
  opacity: 0;
  animation: shoot var(--dur, 1.2s) ease-in forwards;
}

@keyframes shoot {
  0%   { opacity: 0; transform: rotate(var(--angle)) translateX(0); }
  15%  { opacity: 0.7; }
  100% { opacity: 0; transform: rotate(var(--angle)) translateX(var(--travel)); }
}

/* ── Birds (morning) ── */
.bird {
  position: absolute;
  top: 0;
  left: 0;
  width: var(--size, 18px);
  height: calc(var(--size, 18px) * 0.55);
  pointer-events: none;
  z-index: 0;
  opacity: 0;
  animation: fly var(--dur, 10s) linear forwards;
}

.bird .bird-body {
  width: 100%;
  height: 100%;
  animation: soar var(--cycle, 2.6s) ease-in-out var(--phase, 0s) infinite;
}

.bird svg {
  width: 100%;
  height: 100%;
  overflow: visible;
  fill: none;
  stroke: var(--color-bird, #3a4766);
  stroke-width: 2.6;
  stroke-linecap: round;
  stroke-linejoin: round;
  transform: scaleX(var(--dir, 1)) rotate(var(--tilt, 0deg));
}

.bird .body { fill: var(--color-bird, #3a4766); stroke: none; }

.bird .wing {
  transform-origin: 20px 12px;
  animation: flap var(--cycle, 2.6s) ease-in-out var(--phase, 0s) infinite;
}
.bird .wing.left { --s: -1; }
.bird .wing.right { --s: 1; }

/* three wingbeats, then a glide with wings held in a shallow V */
@keyframes flap {
  0%   { transform: rotate(calc(var(--s) * -30deg)); }
  7%   { transform: rotate(calc(var(--s) * 32deg)); }
  16%  { transform: rotate(calc(var(--s) * -30deg)); }
  23%  { transform: rotate(calc(var(--s) * 32deg)); }
  32%  { transform: rotate(calc(var(--s) * -30deg)); }
  39%  { transform: rotate(calc(var(--s) * 32deg)); }
  50%  { transform: rotate(calc(var(--s) * -16deg)); }
  88%  { transform: rotate(calc(var(--s) * -14deg)); }
  100% { transform: rotate(calc(var(--s) * -30deg)); }
}

/* rise while flapping, sink while gliding */
@keyframes soar {
  0%   { transform: translateY(0); }
  48%  { transform: translateY(calc(-1 * var(--lift, 3px))); }
  100% { transform: translateY(0); }
}

@keyframes fly {
  0%   { opacity: 0; transform: translate(0, 0); }
  6%   { opacity: var(--op, 0.8); }
  94%  { opacity: var(--op, 0.8); }
  100% { opacity: 0; transform: translate(var(--travel), var(--drop, 0px)); }
}

@media (prefers-reduced-motion: reduce) {
  .shooting-star, .bird { display: none; }
}

body {
  font-family: var(--font-mono);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.75;
  padding: 3rem 1.5rem 4rem;
  font-size: 14px;
  transition: background-color 0.4s ease, color 0.4s ease;
}

::selection {
  background: var(--color-accent);
  color: var(--color-bg);
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
}

/* ── Header ── */
header {
  position: relative;
  overflow: hidden;
  padding: 1.5rem 1.5rem 2rem;
  margin: -1.5rem -1.5rem 2rem;
  border-bottom: 1px solid var(--color-border);
  border-radius: 12px 12px 0 0;
}

header::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 0;
  background:
    radial-gradient(ellipse at 75% -10%, rgba(122, 162, 247, 0.14), transparent 55%),
    radial-gradient(ellipse at 10% 120%, rgba(187, 154, 247, 0.10), transparent 55%);
  pointer-events: none;
}

header > * { position: relative; z-index: 1; }

/* clear morning sky: deeper blue overhead, lighter toward the horizon */
[data-theme="morning"] header::before {
  background: linear-gradient(180deg, #a9d1f1 0%, #c3dff5 30%, #dfeefa 58%, #eff5fc 82%, var(--color-bg) 100%);
}

/* soft cumulus clouds drifting across the morning sky (built in main.js) */
.clouds {
  position: absolute;
  inset: 0;
  z-index: 0;
  overflow: hidden;
  pointer-events: none;
  display: none;
}

[data-theme="morning"] .clouds { display: block; }

.cloud {
  position: absolute;
  left: 0;
  top: var(--top);
  width: var(--w);
  height: var(--h);
  opacity: var(--op, 0.7);
  filter: blur(var(--blur, 2px));
  animation: cloud-drift var(--cd, 160s) linear var(--cdelay, 0s) infinite;
  will-change: transform;
}

@keyframes cloud-drift {
  from { transform: translateX(calc(-1 * var(--w))); }
  to   { transform: translateX(var(--travel)); }
}

@media (prefers-reduced-motion: reduce) {
  .cloud { animation: none; transform: translateX(calc(var(--travel) * 0.45)); }
}

[data-theme="morning"] .starfield { display: none; }
[data-theme="morning"] header { border-bottom-color: transparent; }
[data-theme="morning"] footer { border-top-color: transparent; }
[data-theme="morning"] header .links a { color: #5f6c8f; }

/* ── Theme toggle ── */
.theme-toggle {
  position: absolute;
  top: 1.1rem;
  right: 1.1rem;
  z-index: 2;
  width: 34px;
  height: 34px;
  padding: 0;
  border-radius: 50%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  color: var(--color-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.25s ease;
}

.theme-toggle:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
  box-shadow: 0 0 12px rgba(var(--color-accent-rgb), 0.15);
}

.theme-toggle svg {
  width: 16px;
  height: 16px;
  fill: currentColor;
}

.theme-toggle .icon-moon { display: none; }
[data-theme="morning"] .theme-toggle .icon-sun { display: none; }
[data-theme="morning"] .theme-toggle .icon-moon { display: block; }

.starfield {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
}

.starfield .star {
  position: absolute;
  width: var(--size, 2px);
  height: var(--size, 2px);
  border-radius: 50%;
  background: #fff;
  opacity: 0;
  box-shadow: 0 0 var(--glow, 3px) rgba(192, 202, 245, 0.7);
  animation: twinkle var(--tw, 4s) ease-in-out var(--delay, 0s) infinite;
}

@keyframes twinkle {
  0%, 100% { opacity: 0.15; }
  50%      { opacity: var(--base, 0.85); }
}

@media (prefers-reduced-motion: reduce) {
  .starfield .star { animation: none; opacity: var(--base, 0.6); }
}

header .bio {
  color: var(--color-text-soft);
  font-size: 0.85rem;
  margin-top: 0.75rem;
  line-height: 1.8;
  text-align: justify;
}

header h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.2rem;
  padding-right: 3rem;
  color: var(--color-heading);
}

header .tagline {
  color: var(--color-tagline);
  font-size: 0.9rem;
}

header .links {
  margin-top: 1rem;
  display: flex;
  gap: 1rem;
  align-items: center;
}

header .links a {
  color: var(--color-muted);
  text-decoration: none;
  transition: color 0.2s ease;
  display: flex;
}

header .links a:hover {
  color: var(--color-accent);
}

header .links a svg {
  width: 20px;
  height: 20px;
  fill: currentColor;
}

/* ── Navigation ── */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-bg);
  transition: background-color 0.4s ease;
  display: flex;
  gap: 0.6rem;
  padding: 0.75rem 0;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

nav a {
  color: var(--color-text);
  text-decoration: none;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.5rem 1.15rem;
  border-radius: 8px;
  background: var(--color-accent-dim);
  border: 1px solid transparent;
  transition: all 0.25s ease;
}

nav a:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
  background: rgba(var(--color-accent-rgb), 0.08);
  box-shadow: 0 0 12px rgba(var(--color-accent-rgb), 0.15);
}

/* ── Sections ── */
section {
  margin-bottom: 3rem;
}

section h2 {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-accent);
  text-shadow: 0 0 16px rgba(var(--color-accent-rgb), var(--glow-alpha));
  margin-bottom: 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

section h2::before {
  content: "#";
  color: var(--color-accent);
  font-weight: 700;
  opacity: 0.7;
}

section h2::after {
  content: "";
  flex: 1;
  height: 1px;
  background: linear-gradient(90deg, var(--color-border), transparent);
}

/* ── Entry items ── */
.entry {
  margin-bottom: 1.25rem;
  padding-left: 1rem;
  border-left: 2px solid var(--color-border);
  transition: border-color 0.2s ease;
}

.entry.inline {
  display: flex;
  gap: 1rem;
  align-items: baseline;
}

.entry.inline .date {
  flex-shrink: 0;
  min-width: 5.5rem;
  margin-bottom: 0;
}

.entry:hover {
  border-left-color: var(--color-accent);
}

.entry .date {
  font-size: 0.75rem;
  color: var(--color-purple);
  font-weight: 600;
  margin-bottom: 0.2rem;
}

.entry .title {
  font-weight: 600;
  font-size: 0.92rem;
  color: var(--color-text);
}

.entry .title a {
  color: var(--color-text);
  text-decoration: none;
}

.entry .title a:hover {
  color: var(--color-accent);
}

.entry .detail {
  color: var(--color-text-soft);
  font-size: 0.82rem;
  margin-top: 0.15rem;
  text-align: justify;
}

.entry .detail a {
  color: var(--color-accent);
  text-decoration: none;
}

.entry .detail a:hover { text-decoration: underline; }

.entry .highlight {
  display: block;
  margin-top: 0.5rem;
  padding: 0.35rem 0.7rem;
  font-size: 0.82rem;
  color: var(--color-text);
  background: var(--color-accent-dim);
  border-left: 3px solid var(--color-accent);
  border-radius: 0 6px 6px 0;
}

/* ── Type tag ── */
.entry .tag {
  display: inline-block;
  font-size: 0.68rem;
  font-weight: 600;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  margin-top: 0.3rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.entry .tag.grant {
  color: var(--color-green);
  background: rgba(158, 206, 106, 0.12);
}

.entry .tag.fellowship {
  color: var(--color-purple);
  background: rgba(187, 154, 247, 0.12);
}

.entry .tag.invited {
  color: var(--color-accent);
  background: var(--color-accent-dim);
}

.entry .tag.seminar {
  color: var(--color-cyan);
  background: rgba(125, 207, 255, 0.12);
}

.entry .tag.award {
  color: var(--color-yellow);
  background: rgba(224, 175, 104, 0.12);
}

.entry .tag + .tag {
  margin-left: 0.15rem;
}

.entry.inline .tag {
  margin-top: 0;
}

.entry.inline .tag:last-of-type {
  margin-right: 0.35rem;
}

/* ── Section note ── */
.section-note {
  color: var(--color-text-soft);
  font-size: 0.82rem;
}

.section-note a {
  color: var(--color-accent);
  text-decoration: none;
}

.section-note a:hover { text-decoration: underline; }

/* ── Back to top ── */
.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  color: var(--color-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  opacity: 0;
  pointer-events: none;
  transition: all 0.25s ease;
}

.back-to-top.visible {
  opacity: 1;
  pointer-events: auto;
}

.back-to-top:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
  box-shadow: 0 0 12px rgba(var(--color-accent-rgb), 0.15);
}

.back-to-top svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

/* ── Footer ── */
footer {
  position: relative;
  overflow: hidden;
  margin: 3rem -1.5rem 0;
  padding: 2.25rem 1.5rem;
  border-top: 1px solid var(--color-border);
  border-radius: 0 0 12px 12px;
  color: var(--color-muted);
  font-size: 0.75rem;
  text-align: center;
}

footer::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 0;
  background:
    radial-gradient(ellipse at 25% 130%, rgba(122, 162, 247, 0.12), transparent 55%),
    radial-gradient(ellipse at 90% -20%, rgba(187, 154, 247, 0.10), transparent 55%);
  pointer-events: none;
}

footer > * { position: relative; z-index: 1; }

[data-theme="morning"] footer::before {
  background: linear-gradient(0deg, #a9d1f1 0%, #c3dff5 30%, #dfeefa 58%, #eff5fc 82%, var(--color-bg) 100%);
}

/* ── Responsive ── */
@media (max-width: 600px) {
  body { padding: 1.5rem 1rem 3rem; }
  header h1 { font-size: 1.4rem; }
  nav { gap: 0.25rem; }
  .back-to-top { bottom: 1.25rem; right: 1.25rem; }
}