:root {
	--heat: 0;
	--ink: #e9f4fb;
	--muted: #9fbccd;
	--accent: #7fd6ff;
	--warm: #ff9a5a;
	--card: rgba(12, 32, 52, .62);
	--line: rgba(160, 210, 235, .18);
	color-scheme: dark;
}

* { box-sizing: border-box; }

html, body { margin: 0; }

body {
	min-height: 100vh;
	display: flex;
	flex-direction: column;
	font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
	color: var(--ink);
	background: #081a2e;
}

/* Polar sky that warms up as more ice is lost (--heat goes 0 → 1). */
.sky {
	position: fixed;
	inset: 0;
	z-index: -1;
	background:
		radial-gradient(60% 40% at 20% 10%, rgba(80, 230, 180, .16), transparent 70%),
		radial-gradient(50% 35% at 80% 0%, rgba(120, 140, 255, .14), transparent 70%),
		linear-gradient(#071628 0%, #0f2c47 55%, #2a5672 100%);
}
.sky::before {
	content: "";
	position: absolute;
	inset: -10%;
	background:
		radial-gradient(40% 30% at 30% 20%, rgba(90, 255, 190, .12), transparent 70%),
		radial-gradient(35% 25% at 70% 15%, rgba(140, 120, 255, .10), transparent 70%);
	animation: aurora 24s ease-in-out infinite alternate;
}
.sky::after {
	content: "";
	position: absolute;
	inset: 0;
	background: linear-gradient(rgba(120, 40, 0, .5), rgba(200, 90, 20, .75));
	opacity: calc(var(--heat) * .75);
}

@keyframes aurora {
	from { transform: translate(-3%, 0) scale(1); }
	to   { transform: translate(4%, 3%) scale(1.08); }
}

main {
	width: min(1120px, 100% - 2rem);
	margin: 0 auto;
	padding-top: clamp(1.5rem, 5vh, 3.5rem);
}

header { text-align: center; margin-bottom: 1.2rem; }

.panel { display: grid; gap: 1rem; }
.panel > * { min-width: 0; }
@media (min-width: 900px) {
	.panel { grid-template-columns: 1.1fr 1fr; align-items: stretch; }
	.result { margin-top: 0 !important; display: flex; flex-direction: column; justify-content: center; }
}

.eyebrow {
	margin: 0 0 .4rem;
	font-size: .78rem;
	letter-spacing: .14em;
	text-transform: uppercase;
	color: var(--accent);
}

.intro {
	max-width: 46rem;
	margin: .7rem auto 0;
	color: var(--muted);
	text-wrap: balance;
}

h1 {
	margin: 0;
	font-size: clamp(1.6rem, 4.2vw, 2.6rem);
	line-height: 1.15;
	font-weight: 700;
	text-wrap: balance;
}

.card {
	background: var(--card);
	border: 1px solid var(--line);
	border-radius: 18px;
	padding: 1.25rem 1.4rem;
	backdrop-filter: blur(10px);
	-webkit-backdrop-filter: blur(10px);
	box-shadow: 0 20px 50px -25px rgba(0, 0, 0, .6);
}

/* The form reads as a sentence. */
.sentence {
	margin: 0;
	display: flex;
	flex-wrap: wrap;
	align-items: center;
	gap: .5rem .55rem;
	font-size: 1.1rem;
}

input, select {
	font: inherit;
	color: var(--ink);
	background: rgba(255, 255, 255, .07);
	border: 1px solid var(--line);
	border-radius: 10px;
	padding: .35rem .6rem;
	transition: border-color .2s, background .2s;
}
input:hover, select:hover { background: rgba(255, 255, 255, .11); }
input:focus-visible, select:focus-visible, summary:focus-visible, .presets button:focus-visible {
	outline: 2px solid var(--accent);
	outline-offset: 2px;
}
select option, select optgroup { background: #0f2c47; color: var(--ink); }
input[type=number] { width: 5.5rem; }
select { max-width: 100%; }

.unit-input { display: inline-flex; align-items: center; gap: .35rem; }
[hidden] { display: none !important; }

.presets {
	display: flex;
	flex-wrap: wrap;
	gap: .45rem;
	margin-top: 1rem;
	padding-top: .9rem;
	border-top: 1px solid var(--line);
}
.presets button {
	font: inherit;
	font-size: .85rem;
	color: var(--muted);
	background: transparent;
	border: 1px solid var(--line);
	border-radius: 999px;
	padding: .25rem .8rem;
	cursor: pointer;
	transition: color .2s, border-color .2s, background .2s;
}
.presets button:hover { color: var(--ink); border-color: var(--accent); background: rgba(127, 214, 255, .08); }

.result { text-align: center; }

.headline { margin: 0; }
.area {
	display: block;
	font-size: clamp(2.4rem, 8vw, 4.2rem);
	font-weight: 800;
	line-height: 1.1;
	letter-spacing: -.02em;
	font-variant-numeric: tabular-nums;
	white-space: nowrap;
}
.area > span { display: inline-block; transition: min-width .6s ease; }
.area .num {
	text-align: right;
	background: linear-gradient(90deg, #ffffff, #c4ecff);
	-webkit-background-clip: text;
	background-clip: text;
	color: transparent;
}
.area .unit { text-align: left; margin-left: .2em; color: var(--accent); }
.area.measure { position: absolute; left: -9999px; top: 0; visibility: hidden; }
.headline { position: relative; }
.of { color: var(--muted); font-size: 1.05rem; }

.compare { margin: .35rem 0 0; font-size: 1.05rem; min-height: 1.6em; }

.stats {
	display: grid;
	grid-template-columns: repeat(3, 1fr);
	gap: .5rem;
	margin: 1rem 0 0;
	padding-top: .9rem;
	border-top: 1px solid var(--line);
}
.stats dt { font-size: .75rem; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.stats dd { margin: 0; font-weight: 600; font-variant-numeric: tabular-nums; }

/* Scene */
#scene {
	display: block;
	width: 100%;
	flex: 1 0 clamp(260px, 42vh, 460px);
	margin-top: -1rem;
	pointer-events: none;
}

.wave { animation: drift 9s linear infinite; }
.wave.w2 { animation-duration: 13s; animation-direction: reverse; }
.wave.w3 { animation-duration: 17s; }
@keyframes drift { to { transform: translateX(120px); } }

.ripple { fill: none; stroke: #cdeefc; }

#penguin .tear { opacity: 0; }
#penguin.sad .tear { animation: tear 2.6s ease-in infinite; }
@keyframes tear {
	0%   { opacity: 0; transform: translateY(0); }
	20%  { opacity: 1; }
	80%  { opacity: 1; transform: translateY(16px); }
	100% { opacity: 0; transform: translateY(20px); }
}
#penguin .wing { transform-origin: -22px -44px; }
#penguin .wing.r { transform-origin: 22px -44px; }
#penguin.shiver { animation: shiver .18s linear infinite alternate; }
@keyframes shiver {
	from { transform: scale(1.15); }
	to   { transform: scale(1.15) translateX(.8px); }
}

.below {
	background: #0b2236;
	padding: 1.5rem 1rem 1rem;
}
.method { width: min(1120px, 100%); margin: 0 auto; background: rgba(255, 255, 255, .03); }
.method summary { cursor: pointer; font-weight: 600; }
.method h2 { font-size: 1rem; margin: 1.2rem 0 .3rem; }
.method li { margin-bottom: .45rem; }
.method p, .method li { color: #c8dce8; font-size: .95rem; }
a { color: var(--accent); }

footer { text-align: center; color: var(--muted); font-size: .85rem; padding: 1rem 0 .5rem; }

@media (max-width: 560px) {
	.sentence { font-size: 1rem; }
	.stats { grid-template-columns: 1fr; text-align: center; }
	#country { max-width: 100%; }
}

@media (prefers-reduced-motion: reduce) {
	.sky::before, .wave, #penguin.sad .tear, #penguin.shiver { animation: none; }
}