:root {
    color-scheme: light dark;
    --bg-gradient: radial-gradient(1200px 800px at 10% -10%, #0ea5e9 0%, transparent 45%),
                   radial-gradient(1000px 700px at 110% 10%, #22d3ee 0%, transparent 40%),
                   radial-gradient(900px 900px at 50% 120%, #38bdf8 0%, transparent 35%),
                   linear-gradient(180deg, #0b1220, #0f172a 60%, #0b1220);
    --card-bg: rgba(17, 25, 40, 0.65);
    --card-border: rgba(148, 163, 184, 0.18);
    --card-highlight: rgba(56, 189, 248, 0.25);
    --accent: #38bdf8;
    --accent-strong: #0ea5e9;
    --text-primary: #e2e8f0;
    --text-secondary: #94a3b8;
    --error: #f87171;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    min-height: 100vh;
    font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    background: var(--bg-gradient);
    background-attachment: fixed;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 48px 16px;
    position: relative;
    overflow-x: hidden;
}

main { width: min(1000px, 100%); position: relative; }

/* Ornaments */
.bg-orbs { position: absolute; inset: -10% -10% auto -10%; pointer-events: none; filter: blur(40px); z-index: 0; }
.bg-orbs .orb { position: absolute; border-radius: 999px; opacity: 0.35; mix-blend-mode: screen; animation: float 14s ease-in-out infinite; }
.bg-orbs .orb.orb-1 { width: 320px; height: 320px; left: -40px; top: -60px; background: #22d3ee; animation-delay: 0s; }
.bg-orbs .orb.orb-2 { width: 420px; height: 420px; right: -60px; top: -40px; background: #60a5fa; animation-delay: 2s; }
.bg-orbs .orb.orb-3 { width: 280px; height: 280px; right: 10%; bottom: -80px; background: #38bdf8; animation-delay: 4s; }

@keyframes float { 0%,100% { transform: translateY(0) translateX(0) scale(1); } 50% { transform: translateY(-12px) translateX(8px) scale(1.03); } }

.calculator-card {
    position: relative;
    z-index: 1;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 28px;
    padding: 36px;
    backdrop-filter: blur(22px) saturate(120%);
    box-shadow: 0 24px 80px rgba(8, 47, 73, 0.45), inset 0 1px 0 rgba(255, 255, 255, 0.06);
}

.card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    margin-bottom: 22px;
}

.brand {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
}

.brand-logo {
    width: clamp(110px, 16vw, 140px);
    height: auto;
    filter: drop-shadow(0 12px 30px rgba(14, 165, 233, 0.2));
}

.brand-tagline {
    font-size: 0.8rem;
    color: var(--text-secondary);
    letter-spacing: 0.03em;
    text-transform: uppercase;
}

h1 { font-size: clamp(2rem, 3vw, 2.75rem); margin: 0 0 10px; font-weight: 800; letter-spacing: -0.02em; }

p.subtitle { margin: 0 0 28px; color: var(--text-secondary); font-size: 1.02rem; }

.lang-toggle { display: flex; gap: 10px; justify-content: flex-end; }
.lang-toggle a {
    padding: 9px 16px;
    border-radius: 999px;
    border: 1px solid rgba(148, 163, 184, 0.22);
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 700;
    letter-spacing: 0.02em;
    transition: all 0.2s ease;
    background: linear-gradient(180deg, rgba(15,23,42,0.65), rgba(15,23,42,0.45));
}
.lang-toggle a:hover { border-color: var(--accent); color: var(--text-primary); box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.18) inset; }
.lang-toggle a.active {
    color: #0b1220;
    background: linear-gradient(135deg, var(--accent), var(--accent-strong));
    border-color: transparent;
    box-shadow: 0 16px 32px rgba(14, 165, 233, 0.35);
}

form { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 22px; }
.form-group { display: flex; flex-direction: column; gap: 8px; }
label { font-size: 0.95rem; font-weight: 600; letter-spacing: 0.02em; color: #cbd5e1; }

select, input[type="number"], input[type="text"] {
    appearance: none;
    border: 1px solid rgba(148, 163, 184, 0.22);
    border-radius: 16px;
    padding: 14px 14px;
    background: linear-gradient(180deg, rgba(15,23,42,0.7), rgba(15,23,42,0.5));
    color: var(--text-primary);
    font-size: 1rem;
    transition: border 0.2s ease, box-shadow 0.2s ease, transform 0.05s ease;
    outline: none;
}
select:focus, input:focus { border-color: var(--accent); box-shadow: 0 0 0 4px rgba(56, 189, 248, 0.22), 0 10px 30px rgba(14, 165, 233, 0.12); }
select:hover, input:hover { border-color: rgba(148, 163, 184, 0.35); }
input:active { transform: translateY(0.5px); }

.solvent-hint { font-size: 0.8rem; color: var(--text-secondary); }

.submit-group { grid-column: 1 / -1; display: flex; justify-content: flex-end; }
button {
    border: none;
    border-radius: 16px;
    padding: 14px 28px;
    font-size: 1rem;
    font-weight: 800;
    letter-spacing: 0.02em;
    color: #0b1220;
    background: linear-gradient(135deg, var(--accent), var(--accent-strong));
    cursor: pointer;
    transition: transform 0.15s ease, box-shadow 0.15s ease, filter 0.2s ease;
    box-shadow: 0 16px 36px rgba(14, 165, 233, 0.38);
}
button:hover { transform: translateY(-2px); box-shadow: 0 22px 44px rgba(14, 165, 233, 0.42); filter: saturate(110%); }
button:active { transform: translateY(0px) scale(0.99); }

.error {
    grid-column: 1 / -1;
    padding: 12px 16px;
    border-radius: 16px;
    border: 1px solid rgba(248, 113, 113, 0.25);
    background: linear-gradient(180deg, rgba(248, 113, 113, 0.12), rgba(248, 113, 113, 0.08));
    color: var(--error);
    font-weight: 600;
}

.results { margin-top: 32px; display: grid; gap: 22px; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.results-card {
    padding: 26px;
    border-radius: 22px;
    background: linear-gradient(180deg, rgba(15,23,42,0.75), rgba(15,23,42,0.6));
    border: 1px solid rgba(148, 163, 184, 0.15);
    box-shadow: 0 16px 40px rgba(8, 47, 73, 0.35), inset 0 1px 0 rgba(255,255,255,0.05);
}
.results-card h3 { margin: 0 0 16px; font-size: 1.05rem; letter-spacing: 0.02em; color: var(--text-secondary); font-weight: 700; }
.result-row { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 12px; font-size: 0.96rem; }
.result-row strong { font-size: 1.12rem; color: var(--text-primary); }

@media (max-width: 640px) {
    .calculator-card { padding: 26px; }
    .card-header { flex-direction: column; align-items: flex-start; gap: 18px; }
    .brand { align-items: flex-start; }
    .lang-toggle { width: 100%; justify-content: flex-start; }
    .submit-group { justify-content: stretch; }
    button { width: 100%; }
}