/* ==========================================================================
   WorkCalc — Core Design System & Responsive Styles
   Clean SaaS, Accessible, Zero-Dependency CSS
   ========================================================================== */

:root {
    --color-bg: #f8fafc;
    --color-surface: #ffffff;
    --color-surface-hover: #f1f5f9;
    --color-border: #e2e8f0;
    --color-border-focus: #2563eb;

    --color-text-main: #0f172a;
    --color-text-muted: #475569;
    --color-text-light: #64748b;

    --color-primary: #2563eb;
    --color-primary-hover: #1d4ed8;
    --color-primary-light: #eff6ff;

    --color-accent-green: #059669;
    --color-accent-green-bg: #ecfdf5;
    --color-accent-amber: #d97706;
    --color-accent-amber-bg: #fffbeb;
    --color-accent-red: #dc2626;
    --color-accent-red-bg: #fef2f2;

    --font-sans: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.08), 0 2px 4px -2px rgb(0 0 0 / 0.05);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.07), 0 4px 6px -4px rgb(0 0 0 / 0.05);

    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 14px;
    --radius-full: 9999px;

    --max-width: 1140px;
}

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

body {
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.6;
    color: var(--color-text-main);
    background-color: var(--color-bg);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    -webkit-font-smoothing: antialiased;
}

/* Skip link for Accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 10px;
    background: var(--color-primary);
    color: #fff;
    padding: 8px 16px;
    z-index: 1000;
    border-radius: var(--radius-sm);
    text-decoration: none;
    font-weight: 600;
    transition: top 0.2s ease;
}

.skip-link:focus {
    top: 10px;
}

/* Layout Container */
.container {
    width: 100%;
    max-width: var(--max-width);
    margin-left: auto;
    margin-right: auto;
    padding-left: 1.25rem;
    padding-right: 1.25rem;
}

/* Focus styles */
a:focus-visible,
button:focus-visible,
input:focus-visible,
select:focus-visible {
    outline: 2px solid var(--color-border-focus);
    outline-offset: 2px;
}

/* Header & Nav */
.site-header {
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 68px;
}

.brand-link {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-text-main);
}

.brand-link:hover {
    opacity: 0.9;
}

.brand-logo {
    width: 32px;
    height: 32px;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    list-style: none;
}

.nav-link {
    color: var(--color-text-muted);
    text-decoration: none;
    font-size: 0.9375rem;
    font-weight: 500;
    transition: color 0.15s ease;
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-primary);
}

.mobile-nav-toggle {
    display: none;
    background: none;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    padding: 8px 10px;
    cursor: pointer;
    color: var(--color-text-main);
}

.mobile-nav-toggle svg {
    display: block;
    width: 22px;
    height: 22px;
}

/* Hero Section */
.hero {
    padding: 3.5rem 0 2.5rem;
    text-align: center;
}

.hero-badge {
    display: inline-block;
    background: var(--color-primary-light);
    color: var(--color-primary);
    font-size: 0.8125rem;
    font-weight: 600;
    padding: 4px 12px;
    border-radius: var(--radius-full);
    margin-bottom: 1rem;
}

.hero-title {
    font-size: 2.25rem;
    font-weight: 800;
    letter-spacing: -0.025em;
    color: var(--color-text-main);
    line-height: 1.2;
    margin-bottom: 1rem;
}

.hero-subtitle {
    font-size: 1.125rem;
    color: var(--color-text-muted);
    max-width: 680px;
    margin: 0 auto 2rem;
}

/* Page Intro Block */
.page-header {
    padding: 2.5rem 0 1.5rem;
}

.page-title {
    font-size: 2rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    margin-bottom: 0.75rem;
}

.page-description {
    font-size: 1.0625rem;
    color: var(--color-text-muted);
    max-width: 780px;
}

/* Breadcrumbs */
.breadcrumbs {
    font-size: 0.875rem;
    color: var(--color-text-light);
    margin-bottom: 1rem;
}

.breadcrumbs a {
    color: var(--color-text-muted);
    text-decoration: none;
}

.breadcrumbs a:hover {
    color: var(--color-primary);
    text-decoration: underline;
}

.breadcrumbs span {
    margin: 0 0.5rem;
}

/* Cards & Grid System */
.grid {
    display: grid;
    gap: 1.5rem;
}

.grid-cols-2 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid-cols-3 {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-sm);
    transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.card-hoverable:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: #cbd5e1;
}

.card-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--color-text-main);
}

.card-title a {
    text-decoration: none;
    color: inherit;
}

.card-title a:hover {
    color: var(--color-primary);
}

.card-text {
    font-size: 0.9375rem;
    color: var(--color-text-muted);
    margin-bottom: 1.25rem;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 0.625rem 1.25rem;
    border-radius: var(--radius-md);
    font-size: 0.9375rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    border: 1px solid transparent;
    transition: all 0.15s ease;
    line-height: 1.25;
}

.btn-primary {
    background: var(--color-primary);
    color: #ffffff;
}

.btn-primary:hover {
    background: var(--color-primary-hover);
}

.btn-secondary {
    background: var(--color-surface);
    color: var(--color-text-main);
    border-color: var(--color-border);
}

.btn-secondary:hover {
    background: var(--color-surface-hover);
}

.btn-outline {
    background: transparent;
    color: var(--color-primary);
    border-color: var(--color-primary);
}

.btn-outline:hover {
    background: var(--color-primary-light);
}

.btn-sm {
    padding: 0.375rem 0.75rem;
    font-size: 0.8125rem;
}

/* Calculator Workspace Layout */
.calc-workspace {
    display: grid;
    grid-template-columns: 1.15fr 0.85fr;
    gap: 2rem;
    margin-bottom: 3rem;
    align-items: start;
}

.calc-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 1.75rem;
    box-shadow: var(--shadow-sm);
}

.calc-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1.25rem;
    border-bottom: 1px solid var(--color-border);
    padding-bottom: 0.75rem;
}

/* Forms & Inputs */
.form-group {
    margin-bottom: 1.25rem;
}

.form-label {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.15rem;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 0.375rem;
  color: var(--color-text-main);
}

.form-label-hint {
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--color-text-light);
  line-height: 1.3;
}

.input-affix-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.input-prefix,
.input-suffix {
    position: absolute;
    color: var(--color-text-light);
    font-size: 0.9375rem;
    pointer-events: none;
}

.input-prefix {
    left: 0.875rem;
}

.input-suffix {
    right: 0.875rem;
}

.form-control {
    width: 100%;
    padding: 0.625rem 0.875rem;
    font-size: 0.9375rem;
    font-family: var(--font-sans);
    color: var(--color-text-main);
    background: #ffffff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.form-control.has-prefix {
    padding-left: 2rem;
}

.form-control.has-suffix {
    padding-right: 2.5rem;
}

.form-control:focus {
    border-color: var(--color-border-focus);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

.form-actions {
    display: flex;
    gap: 0.75rem;
    margin-top: 1.5rem;
}

/* Results Panel */
.results-panel {
    background: #f8fafc;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    position: sticky;
    top: 90px;
}

.results-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.25rem;
}

.results-title {
    font-size: 1.125rem;
    font-weight: 700;
}

.metric-highlight {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 1.25rem;
    margin-bottom: 1rem;
}

.metric-label {
    font-size: 0.8125rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-light);
    margin-bottom: 0.25rem;
}

.metric-value {
    font-size: 1.875rem;
    font-weight: 800;
    color: var(--color-primary);
    font-family: var(--font-mono);
    line-height: 1.2;
}

.metric-value.positive {
    color: var(--color-accent-green);
}

.metric-value.negative {
    color: var(--color-accent-red);
}

.metric-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-bottom: 1.25rem;
}

.metric-item {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    font-size: 0.9375rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px dashed var(--color-border);
}

.metric-item:last-child {
    border-bottom: none;
}

.metric-item-label {
    color: var(--color-text-muted);
}

.metric-item-value {
    font-weight: 700;
    font-family: var(--font-mono);
    color: var(--color-text-main);
}

/* Notice & Alerts */
.calc-alert {
    padding: 0.75rem 1rem;
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    margin-bottom: 1.25rem;
    display: none;
}

.calc-alert.visible {
    display: block;
}

.calc-alert-warning {
    background: var(--color-accent-amber-bg);
    border: 1px solid #fcd34d;
    color: #92400e;
}

.calc-alert-error {
    background: var(--color-accent-red-bg);
    border: 1px solid #fca5a5;
    color: #991b1b;
}

.calc-disclaimer {
    font-size: 0.75rem;
    color: var(--color-text-light);
    margin-top: 1rem;
    line-height: 1.5;
}

/* Toast message for Copy */
.toast-msg {
    font-size: 0.8125rem;
    color: var(--color-accent-green);
    font-weight: 600;
    opacity: 0;
    transition: opacity 0.2s ease;
}

.toast-msg.show {
    opacity: 1;
}

/* Guide Content Styles */
.guide-article {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 2.5rem;
    margin-bottom: 3rem;
    max-width: 860px;
}

.guide-article h2 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-top: 2rem;
    margin-bottom: 1rem;
    color: var(--color-text-main);
    border-bottom: 1px solid var(--color-border);
    padding-bottom: 0.5rem;
}

.guide-article h3 {
    font-size: 1.1875rem;
    font-weight: 600;
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
}

.guide-article p {
    margin-bottom: 1.25rem;
    color: var(--color-text-muted);
    font-size: 1.0625rem;
}

.guide-article ul,
.guide-article ol {
    margin-bottom: 1.25rem;
    padding-left: 1.5rem;
    color: var(--color-text-muted);
}

.guide-article li {
    margin-bottom: 0.5rem;
}

.guide-callout {
    background: var(--color-primary-light);
    border-left: 4px solid var(--color-primary);
    padding: 1.25rem;
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    margin: 1.5rem 0;
}

.guide-callout p {
    margin-bottom: 0;
    color: #1e3a8a;
    font-size: 0.9375rem;
}

/* Section blocks */
.section {
    padding: 3rem 0;
}

.section-header {
    margin-bottom: 2rem;
}

.section-title {
    font-size: 1.75rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
}

.section-subtitle {
    color: var(--color-text-muted);
    font-size: 1.0625rem;
}

/* Features Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.5rem;
}

.feature-box {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
}

.feature-icon {
    width: 42px;
    height: 42px;
    border-radius: var(--radius-md);
    background: var(--color-primary-light);
    color: var(--color-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
}

/* Footer */
.site-footer {
    margin-top: auto;
    background: var(--color-surface);
    border-top: 1px solid var(--color-border);
    padding: 3.5rem 0 2rem;
    font-size: 0.875rem;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 3rem;
    margin-bottom: 2.5rem;
}

.footer-brand p {
    color: var(--color-text-muted);
    margin-top: 0.75rem;
    max-width: 320px;
}

.footer-heading {
    font-size: 0.875rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-main);
    margin-bottom: 1rem;
}

.footer-links {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.footer-links a {
    color: var(--color-text-muted);
    text-decoration: none;
}

.footer-links a:hover {
    color: var(--color-primary);
}

.footer-bottom {
    border-top: 1px solid var(--color-border);
    padding-top: 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--color-text-light);
    font-size: 0.8125rem;
}

/* Responsive Breakpoints */
@media (max-width: 900px) {
    .calc-workspace {
        grid-template-columns: 1fr;
    }

    .results-panel {
        position: static;
    }

    .features-grid,
    .grid-cols-3 {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .footer-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 680px) {
    .hero-title {
        font-size: 1.875rem;
    }

    .grid-cols-2,
    .grid-cols-3,
    .features-grid {
        grid-template-columns: 1fr;
    }

    .footer-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .footer-bottom {
        flex-direction: column;
        gap: 0.75rem;
        text-align: center;
    }

    .guide-article {
        padding: 1.5rem;
    }

   .mobile-nav-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-left: auto; /* Прижимает иконку бургера строго к правому краю */
  }

  .site-header nav {
    display: contents; /* Исключает тег nav из расчёта ширины шапки */
  }

  .nav-menu {
    display: none;
    position: absolute;
    top: 68px;
    left: 0;
    width: 100%;
    background: var(--color-surface);
    border-bottom: 2px solid var(--color-border);
    flex-direction: column;
    padding: 0.75rem 1.25rem 1.25rem;
    gap: 0.35rem;
    box-shadow: var(--shadow-lg);
    z-index: 1000;
  }

  .nav-menu.open {
    display: flex;
  }

  .nav-menu li {
    width: 100%;
  }

  .nav-menu .nav-link {
    display: block;
    width: 100%;
    padding: 0.75rem 1rem;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 500;
    color: var(--color-text-main);
    transition: background 0.15s ease, color 0.15s ease;
  }

  .nav-menu .nav-link:hover,
  .nav-menu .nav-link.active {
    background: var(--color-primary-light);
    color: var(--color-primary);
  }
}