:root {
    color-scheme: light dark;
    --background: #f8fafc;
    --surface: #ffffff;
    --surface-muted: #f1f5f9;
    --text: #0f172a;
    --muted: #475569;
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --accent: #22c55e;
    --border: rgba(15, 23, 42, 0.12);
    --shadow-soft: 0 12px 32px rgba(15, 23, 42, 0.08);
    --radius: 16px;
    font-family: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    background-color: var(--background);
    color: var(--text);
    line-height: 1.5;
}

[data-theme="dark"] {
    --background: #0f172a;
    --surface: #111c33;
    --surface-muted: #1e293b;
    --text: #e2e8f0;
    --muted: #94a3b8;
    --border: rgba(148, 163, 184, 0.18);
    --shadow-soft: 0 20px 40px rgba(15, 23, 42, 0.32);
}

.high-contrast {
    --background: #ffffff;
    --surface: #ffffff;
    --surface-muted: #f0f0f0;
    --text: #000000;
    --muted: #1f2937;
    --border: rgba(0, 0, 0, 0.25);
    --primary: #111827;
    --primary-dark: #000000;
}

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

body {
    margin: 0;
    background: var(--background);
}

a {
    color: var(--primary);
}

.container {
    width: min(1100px, 92vw);
    margin: 0 auto;
}

.site-header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}
.site-header__inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.1rem 0;
    gap: 1rem;
}
.brand {
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
}
.brand__name {
    font-weight: 700;
    letter-spacing: 0.04rem;
}
.brand__tagline {
    font-size: 0.9rem;
    color: var(--muted);
}
.site-nav {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    font-size: 0.95rem;
}
.site-nav__link {
    text-decoration: none;
    color: var(--muted);
}
.site-nav__link--active {
    color: var(--primary);
    font-weight: 600;
}
.theme-toggle {
    border: none;
    background: var(--surface-muted);
    color: var(--text);
    padding: 0.55rem 0.75rem;
    border-radius: 999px;
    font-size: 1rem;
    cursor: pointer;
}

.site-main {
    padding: 3rem 0 4rem;
}

.hero {
    display: flex;
    justify-content: space-between;
    gap: 2.4rem;
    flex-wrap: wrap;
    align-items: center;
    margin-bottom: 2.8rem;
}
.hero__label {
    text-transform: uppercase;
    letter-spacing: 0.08rem;
    font-size: 0.85rem;
    color: var(--muted);
    margin-bottom: 0.3rem;
}
.hero__title {
    font-size: clamp(2rem, 4vw, 2.8rem);
    margin: 0 0 0.8rem;
}
.hero__subtitle {
    font-size: 1.05rem;
    color: var(--muted);
    margin: 0 0 1rem;
}
.hero__version {
    font-size: 0.85rem;
    color: var(--muted);
}
.hero__actions {
    display: flex;
    gap: 0.8rem;
    flex-wrap: wrap;
}

.btn {
    border-radius: 999px;
    padding: 0.65rem 1.4rem;
    border: 1px solid transparent;
    font: inherit;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.btn:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}
.btn--primary {
    background: var(--primary);
    color: #fff;
    box-shadow: 0 10px 20px rgba(37, 99, 235, 0.18);
}
.btn--primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 12px 24px rgba(37, 99, 235, 0.24);
}
.btn--ghost {
    background: var(--surface-muted);
    color: var(--text);
}

.calculator {
    background: var(--surface);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-soft);
    padding: 1.6rem;
}
.calculator__tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
    margin-bottom: 1.5rem;
}
.calculator__tab {
    border: none;
    background: var(--surface-muted);
    border-radius: 999px;
    padding: 0.55rem 1.1rem;
    cursor: pointer;
    color: var(--muted);
    font-size: 0.95rem;
}
.calculator__tab--active {
    background: var(--primary);
    color: #fff;
    font-weight: 600;
}
.calculator__panels {
    display: grid;
    gap: 1.6rem;
}
.calculator__panel {
    display: none;
}
.calculator__panel--active {
    display: block;
}
.form-grid {
    display: grid;
    gap: 1rem;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    margin-top: 1rem;
}
label span {
    display: block;
    font-weight: 600;
    margin-bottom: 0.45rem;
}
input[type="number"],
textarea {
    width: 100%;
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 0.65rem 0.8rem;
    background: var(--surface-muted);
    color: inherit;
    font: inherit;
}
.form-hint {
    grid-column: 1 / -1;
    font-size: 0.85rem;
    color: var(--muted);
    margin: 0;
}
.inline-options {
    grid-column: 1 / -1;
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 0.8rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.8rem;
}
.inline-options legend {
    font-weight: 600;
    padding: 0 0.4rem;
}
.inline-options label {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    font-size: 0.9rem;
}
.advanced__toggle {
    display: flex;
    gap: 1.2rem;
    flex-wrap: wrap;
    margin-bottom: 1rem;
}
.batch__label {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.results {
    display: grid;
    gap: 1.6rem;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    margin-top: 2.5rem;
}
.results__card {
    background: var(--surface);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    padding: 1.4rem;
    box-shadow: var(--shadow-soft);
    min-height: 200px;
}
.results__value {
    font-size: clamp(1.6rem, 3vw, 2.1rem);
    font-weight: 700;
}
.results__visual {
    margin: 1.2rem 0;
}
.visual-bar {
    background: var(--surface-muted);
    border-radius: 12px;
    height: 16px;
    overflow: hidden;
    position: relative;
}
.visual-bar__fill {
    background: linear-gradient(90deg, var(--primary), var(--accent));
    height: 100%;
    border-radius: inherit;
    transition: width 0.4s ease;
}
.visual-bar__label {
    font-size: 0.9rem;
    color: var(--muted);
    margin-top: 0.4rem;
}
.results__formats p {
    margin: 0.3rem 0;
}
.results__actions {
    margin-top: 1.2rem;
    display: flex;
    gap: 0.6rem;
    flex-wrap: wrap;
}

.history {
    margin-top: 2.8rem;
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.6rem;
    border: 1px solid var(--border);
    box-shadow: var(--shadow-soft);
}
.history__header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.4rem;
}
.history__list {
    display: grid;
    gap: 1rem;
}
.history__item {
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 0.9rem 1rem;
    background: var(--surface-muted);
}
.history__item-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    gap: 0.6rem;
    margin-bottom: 0.4rem;
}
.history__item-value {
    font-weight: 600;
}

.learning {
    margin-top: 3rem;
}
.learning__grid {
    display: grid;
    gap: 1.2rem;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}
.learning__card {
    padding: 1.2rem;
    border-radius: 14px;
    background: var(--surface);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-soft);
    cursor: help;
}

.site-footer {
    background: var(--surface);
    border-top: 1px solid var(--border);
    padding: 2.4rem 0;
    margin-top: 3rem;
}
.site-footer__inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
    color: var(--muted);
}
.site-footer__contact {
    color: var(--primary);
    text-decoration: none;
}

@media (max-width: 720px) {
    .hero {
        flex-direction: column;
        align-items: flex-start;
    }
    .calculator {
        padding: 1.2rem;
    }
    .results {
        grid-template-columns: 1fr;
    }
}