:root {
    --color-primary: #8B4513;
    --color-secondary: #DAA520;
    --color-accent: #4B0082;
    --color-background: #FFF8DC;
    --color-surface: #FFFFFF;
    --color-text: #2F4F4F;
    --color-muted: rgba(47, 79, 79, 0.7);

    --font-heading: 'Cinzel', serif;
    --font-body: 'Lato', sans-serif;

    --spacing-xs: 0.5rem; /* 8px */
    --spacing-sm: 1rem;   /* 16px */
    --spacing-md: 1.5rem; /* 24px */
    --spacing-lg: 2rem;   /* 32px */

    --max-width: 1100px;
    --shadow-soft: 0 2px 4px rgba(0, 0, 0, 0.1);
    --transition-speed: 200ms ease;
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: var(--font-body);
    background-color: var(--color-background);
    color: var(--color-text);
    line-height: 1.6;
}

a {
    color: inherit;
    text-decoration: none;
}

a:focus {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

img {
    max-width: 100%;
    display: block;
}

.container {
    width: min(92%, var(--max-width));
    margin: 0 auto;
}

.site-header {
    background-color: var(--color-surface);
    box-shadow: var(--shadow-soft);
    position: sticky;
    top: 0;
    z-index: 10;
}

.site-header__inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-xs) 0;
}

.brand {
    font-family: var(--font-heading);
    font-size: 1.75rem;
    letter-spacing: 1px;
    color: var(--color-primary);
}

.nav {
    display: flex;
    gap: var(--spacing-xs);
    align-items: center;
}

.theme-selector {
    padding: 0.5rem 0.75rem;
    border-radius: 4px;
    border: 1px solid var(--color-primary);
    background-color: var(--color-surface);
    color: var(--color-primary);
    font-family: var(--font-body);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-speed);
}

.theme-selector:hover {
    background-color: rgba(139, 69, 19, 0.1);
}

.theme-selector:focus {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

.nav__link {
    padding: 0.5rem 0.75rem;
    border-radius: 4px;
    transition: background-color var(--transition-speed), color var(--transition-speed);
}

.nav__link:hover,
.nav__link:focus-visible {
    background-color: rgba(139, 69, 19, 0.1);
    color: var(--color-primary);
}

.section {
    padding: var(--spacing-lg) 0;
}

.section--highlight {
    background: linear-gradient(180deg, rgba(218, 165, 32, 0.15), transparent);
}

.hero {
    display: grid;
    gap: var(--spacing-sm);
    text-align: center;
}

.hero__kicker {
    color: var(--color-accent);
    font-weight: 600;
    letter-spacing: 2px;
    text-transform: uppercase;
}

.hero__title {
    font-family: var(--font-heading);
    font-size: clamp(2rem, 5vw, 3rem);
    margin: 0;
}

.hero__subtitle {
    margin: 0;
    color: var(--color-muted);
    font-size: 1.05rem;
}

.hero__actions {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-sm);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: 4px;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: transform var(--transition-speed), box-shadow var(--transition-speed), background-color var(--transition-speed);
}

.btn--primary {
    background-color: var(--color-primary);
    color: #fff;
    box-shadow: var(--shadow-soft);
}

.btn--primary:hover,
.btn--primary:focus-visible {
    background-color: #6f3610;
    transform: translateY(-1px);
}

.btn--ghost {
    background-color: transparent;
    color: var(--color-primary);
    border: 1px solid var(--color-primary);
}

.btn--ghost:hover,
.btn--ghost:focus-visible {
    background-color: rgba(139, 69, 19, 0.1);
}

.calculator__form.is-submitting .btn--primary {
    opacity: 0.7;
    pointer-events: none;
}

.grid {
    display: grid;
    gap: var(--spacing-sm);
}

.grid--two {
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.card {
    background-color: var(--color-surface);
    padding: var(--spacing-md);
    border-radius: 8px;
    border: 1px solid rgba(47, 79, 79, 0.1);
    box-shadow: var(--shadow-soft);
}

.card__title {
    font-family: var(--font-heading);
    margin-top: 0;
    margin-bottom: var(--spacing-xs);
    font-size: 1.35rem;
}

.card__body {
    margin: 0;
    color: var(--color-muted);
}

.calculator {
    display: grid;
    gap: var(--spacing-sm);
}

.calculator__form {
    display: grid;
    gap: var(--spacing-xs);
}

.label {
    font-weight: 600;
    font-size: 0.95rem;
}

.input {
    padding: 0.75rem;
    border-radius: 4px;
    border: 1px solid #ccc;
    background-color: #fff;
    font: inherit;
    transition: border-color var(--transition-speed), box-shadow var(--transition-speed);
}

.input:focus {
    border-color: var(--color-primary);
    box-shadow: 0 0 0 4px rgba(139, 69, 19, 0.15);
    outline: none;
}

.helper-text {
    color: var(--color-muted);
    font-size: 0.9rem;
}

.result {
    padding: var(--spacing-xs);
    border-radius: 4px;
    background-color: rgba(75, 0, 130, 0.08);
    color: var(--color-accent);
    font-weight: 600;
    display: grid;
    gap: var(--spacing-xs);
}

.result--error {
    background-color: rgba(139, 0, 0, 0.12);
    color: #8B0000;
}

.result__section {
    background-color: rgba(255, 255, 255, 0.9);
    border-radius: 6px;
    border: 1px solid rgba(47, 79, 79, 0.15);
    padding: var(--spacing-xs);
    color: var(--color-text);
    box-shadow: var(--shadow-soft);
}

.result__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-xs);
    margin-bottom: 0.25rem;
}

.result__title {
    margin: 0;
    font-size: 1rem;
    font-family: var(--font-heading);
}

.result__badge {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2rem;
    height: 2rem;
    border-radius: 50%;
    background-color: var(--color-secondary);
    color: #fff;
    font-weight: 700;
}

.result__compound {
    margin: 0;
    font-weight: 600;
    color: var(--color-primary);
}

.result__text,
.result__interpretation {
    margin: 0;
    font-size: 0.95rem;
    color: var(--color-text);
}

.result__interpretation {
    margin-top: 0.25rem;
    color: var(--color-muted);
}

.footer {
    text-align: center;
    padding: var(--spacing-sm) 0 var(--spacing-md);
    color: var(--color-muted);
    font-size: 0.9rem;
}

@media (min-width: 768px) {
    .hero {
        grid-template-columns: repeat(2, minmax(0, 1fr));
        align-items: center;
        text-align: left;
    }

    .hero__actions {
        justify-content: flex-start;
    }

    .calculator {
        grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
        align-items: start;
    }

    .calculator__form {
        order: 1;
    }

    .calculator__result {
        order: 2;
    }
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}