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

:root {
	--bg:      #1c1c1c;
	--bg2:     #252525;
	--bg3:     #2e2e2e;
	--bg4:     #383838;
	--border:  #3a3a3a;
	--border2: #484848;
	--accent:  #4e9fd4;
	--text:    #d4d4d4;
	--muted:   #6a6a6a;
	--sans:    Helvetica Neue, Helvetica, Arial, sans-serif;
}

html, body {
	background: var(--bg);
	color: var(--text);
	font-family: var(--sans);
	font-size: 13px;
	font-weight: 400;
	min-height: 100vh;
	-webkit-font-smoothing: antialiased;
}

body { padding: 36px 20px 60px; }
.container { max-width: 560px; margin: 0 auto; }

/* Header */
header {
	margin-bottom: 32px;
	border-bottom: 1px solid var(--border);
	padding-bottom: 20px;
}
.app-name {
	font-size: 10px; font-weight: 500;
	letter-spacing: 0.14em; text-transform: uppercase;
	color: var(--muted); margin-bottom: 8px;
}
h1 { font-size: 20px; font-weight: 300; color: #e8e8e8; }
h1 strong { font-weight: 500; }
.subtitle { margin-top: 6px; font-size: 11px; color: var(--muted); line-height: 1.6; }

/* Panel */
.panel {
	background: var(--bg2);
	border: 1px solid var(--border);
	border-radius: 4px;
	margin-bottom: 2px;
}
.panel-title {
	font-size: 9px; font-weight: 600;
	letter-spacing: 0.13em; text-transform: uppercase;
	color: var(--muted);
	padding: 12px 18px;
	border-bottom: 1px solid var(--border);
}
.panel-body { padding: 16px 18px; }

/* Fields */
.field { margin-bottom: 12px; }
.field:last-child { margin-bottom: 0; }

label {
	display: block;
	font-size: 11px; color: var(--muted);
	margin-bottom: 5px; letter-spacing: 0.01em;
}

input[type=text], select {
	width: 100%;
	background: var(--bg3);
	border: 1px solid var(--border2);
	border-radius: 3px;
	color: var(--text);
	font-family: var(--sans);
	font-size: 13px;
	padding: 7px 9px;
	outline: none;
	transition: border-color 0.1s;
	-webkit-appearance: none;
}
input[type=text]:focus, select:focus { border-color: var(--accent); }
input[type=text]:disabled {
	background: var(--bg);
	color: var(--muted);
	border-color: var(--border);
	cursor: not-allowed;
}
select { cursor: pointer; }
select option { background: #2e2e2e; }

/* Two-col grid for paired inputs */
.field-pair {
	display: grid;
	grid-template-columns: 1fr 1fr;
	gap: 8px;
	margin-bottom: 12px;
}
.field-pair .field { margin-bottom: 0; }

/* Divider */
.divider {
	border: none;
	border-top: 1px solid var(--border);
	margin: 16px 0;
}

/* Toggle buttons — fit on width/height */
.toggle-group {
	display: flex;
	gap: 0;
	border: 1px solid var(--border2);
	border-radius: 3px;
	overflow: hidden;
}
.toggle-btn {
	flex: 1;
	padding: 7px 10px;
	background: var(--bg3);
	border: none;
	color: var(--muted);
	font-family: var(--sans);
	font-size: 12px;
	cursor: pointer;
	transition: all 0.1s;
	text-align: center;
}
.toggle-btn + .toggle-btn { border-left: 1px solid var(--border2); }
.toggle-btn.active {
	background: rgba(78,159,212,0.12);
	color: var(--accent);
}

/* Calc button */
.btn-wrap {
	padding: 14px 18px;
	border-top: 1px solid var(--border);
}
.btn-calc {
	display: inline-flex;
	align-items: center;
	gap: 7px;
	padding: 8px 22px;
	font-family: var(--sans);
	font-size: 12px; font-weight: 500;
	border-radius: 3px;
	border: 1px solid rgba(78,159,212,0.3);
	cursor: pointer;
	background: rgba(78,159,212,0.10);
	color: var(--accent);
	transition: background 0.1s, border-color 0.1s;
	width: 100%;
	justify-content: center;
}
.btn-calc:hover { background: rgba(78,159,212,0.18); border-color: var(--accent); }

/* Result panel */
.result-panel {
	background: var(--bg2);
	border: 1px solid var(--border);
	border-left: 2px solid var(--border);
	border-radius: 4px;
	transition: border-left-color 0.2s;
}
.result-panel.has-result { border-left-color: var(--accent); }

.result-grid {
	display: grid;
	grid-template-columns: 1fr 1fr;
	gap: 2px;
	background: var(--border);
	border-radius: 0 0 3px 3px;
	overflow: hidden;
}

.result-metric {
	background: var(--bg2);
	padding: 16px 18px 14px;
}
.result-metric-label {
	font-size: 9px; letter-spacing: 0.10em;
	text-transform: uppercase; color: var(--muted);
	margin-bottom: 8px;
}
.result-metric-value {
	font-size: 28px; font-weight: 300;
	color: var(--text); line-height: 1;
	letter-spacing: -0.02em;
}
.result-metric-value.accent { color: var(--accent); font-weight: 400; }
.result-metric-sub {
	font-size: 10px; color: var(--muted); margin-top: 5px;
}

/* Section label inside panel */
.section-label {
	font-size: 9px; font-weight: 600;
	letter-spacing: 0.13em; text-transform: uppercase;
	color: var(--muted);
	margin-bottom: 12px;
	padding-bottom: 8px;
	border-bottom: 1px solid var(--border);
}

footer {
	margin-top: 28px; text-align: center;
	font-size: 10px; color: #4a4a4a; letter-spacing: 0.06em;
}
footer a { color: #4a4a4a; text-decoration: none; }
footer a:hover { color: var(--accent); }