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

@font-face {
  font-family: 'Racama';
  src: url('../assets/fonts/Racama-Regular.woff2') format('woff2');
  font-weight: normal;
  font-style: normal;
  font-display: swap;
}

body {
  background-color: #0a0a0a;
  color: #d0d0d0;
  font-family: 'Racama', Arial, Helvetica, sans-serif;
  line-height: 1.6;
}

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

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

header {
  background-color: #000000;
  border-bottom: 2px solid #1a1a1a;
  padding: 20px 0;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo img {
  display: block;
}

nav {
  display: flex;
  gap: 24px;
}

.nav-link {
  color: #d0d0d0;
  font-size: 0.95rem;
  transition: color 0.3s ease;
}

.nav-link:hover {
  color: #ffffff;
}

.hero {
  padding: 80px 0;
}

.hero h1 {
  font-size: 2.8rem;
  color: #ffffff;
  line-height: 1.2;
}

.hero p {
  font-size: 1.15rem;
  color: #d0d0d0;
  margin-top: 16px;
}

.btn-primary {
  display: inline-block;
  margin-top: 32px;
  background-color: #e8a020;
  color: #000000;
  font-family: 'Racama', Arial, Helvetica, sans-serif;
  font-weight: bold;
  font-size: 1rem;
  padding: 14px 32px;
  border-radius: 6px;
  transition: background-color 0.3s ease;
}

.btn-primary:hover {
  background-color: #f0b030;
}

.section {
  padding: 60px 0;
}

.section-divider {
  border-top: 1px solid #1a1a1a;
}

.section-title {
  font-size: 1.6rem;
  color: #ffffff;
  margin-bottom: 32px;
}

.cards-grid {
  display: grid;
  gap: 20px;
}

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

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

.card {
  display: block;
  background-color: #111111;
  border: 1px solid #222222;
  border-radius: 6px;
  padding: 28px 24px;
  cursor: pointer;
  transition: border-color 0.3s ease;
}

.card:hover {
  border-color: #e8a020;
}

.card-icon {
  font-size: 2rem;
  margin-bottom: 12px;
}

.card-name {
  font-size: 1.1rem;
  color: #ffffff;
  font-weight: bold;
  margin-bottom: 6px;
}

.card-desc {
  font-size: 0.9rem;
  color: #888888;
}

.card-tag {
  display: inline-block;
  background-color: #1a1a1a;
  color: #e8a020;
  font-size: 0.75rem;
  padding: 3px 10px;
  border-radius: 4px;
  margin-bottom: 12px;
}

footer {
  background-color: #000000;
  border-top: 2px solid #1a1a1a;
  padding: 28px 0;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.footer-copy {
  font-size: 0.9rem;
  color: #666666;
}

.footer-link {
  font-size: 0.9rem;
  color: #666666;
  transition: color 0.3s ease;
}

.footer-link:hover {
  color: #ffffff;
}

.hero--inner {
  padding: 60px 0 40px 0;
}

.hero--inner h1 {
  font-size: 2.2rem;
  color: #ffffff;
  line-height: 1.2;
}

.hero--inner p {
  font-size: 1.05rem;
  color: #888888;
  margin-top: 10px;
}

.breadcrumb {
  display: inline-block;
  font-size: 0.9rem;
  color: #666666;
  margin-bottom: 20px;
  transition: color 0.3s ease;
}

.breadcrumb:hover {
  color: #ffffff;
}

.section-title--accent {
  font-size: 1.3rem;
  border-left: 3px solid #e8a020;
  padding-left: 12px;
  margin-bottom: 24px;
}

.cards-grid--calc {
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.card--calc {
  padding: 24px 20px;
  transition: border-color 0.3s ease, transform 0.3s ease;
}

.card--calc:hover {
  border-color: #e8a020;
  transform: translateY(-2px);
}

.card-icon--sm {
  display: block;
  font-size: 1.8rem;
  margin-bottom: 10px;
}

.card--calc .card-name {
  font-size: 1rem;
  margin-bottom: 6px;
}

.card--calc .card-desc {
  font-size: 0.85rem;
  color: #888888;
  line-height: 1.5;
}

.card--stub {
  background-color: #0d0d0d;
  border-color: #1a1a1a;
  cursor: default;
}

.card--stub:hover {
  border-color: #1a1a1a;
  transform: none;
}

.card-name--stub {
  color: #555555;
}

.nav-link--active {
  color: #ffffff;
}

#f-all, #f-elec, #f-plumb {
  display: none;
}

.tags-filter {
  display: flex;
  gap: 8px;
  margin-top: 24px;
}

.tag-filter {
  display: inline-block;
  background-color: #1a1a1a;
  color: #888888;
  font-size: 0.8rem;
  padding: 5px 14px;
  border-radius: 4px;
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease;
}

#f-all:checked ~ main label[for="f-all"],
#f-elec:checked ~ main label[for="f-elec"],
#f-plumb:checked ~ main label[for="f-plumb"] {
  background-color: #e8a020;
  color: #000000;
  font-weight: bold;
}

#f-elec:checked ~ main .cat-plumb {
  display: none;
}

#f-plumb:checked ~ main .cat-elec {
  display: none;
}

.articles-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
  margin-top: 40px;
}

.articles-grid article {
  display: contents;
}

.card--article {
  padding: 24px 20px;
  transition: border-color 0.3s ease, transform 0.3s ease;
}

.card--article:hover {
  border-color: #e8a020;
  transform: translateY(-2px);
}

.article-title {
  font-size: 1rem;
  color: #ffffff;
  font-weight: bold;
  margin-bottom: 8px;
  line-height: 1.4;
}

.article-desc {
  font-size: 0.85rem;
  color: #888888;
  line-height: 1.5;
}

.body--full {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.main--center {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 80px 20px;
}

.error-code {
  font-size: 8rem;
  color: #1a1a1a;
  font-weight: bold;
  line-height: 1;
  margin-bottom: 24px;
}

.error-title {
  font-size: 1.8rem;
  color: #ffffff;
  margin-bottom: 16px;
}

.error-desc {
  font-size: 1rem;
  color: #888888;
  margin-bottom: 40px;
}

.error-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
}

.btn-primary--sm {
  padding: 12px 28px;
}

.btn-outline {
  display: inline-block;
  background: transparent;
  color: #d0d0d0;
  border: 1px solid #333333;
  padding: 12px 28px;
  border-radius: 6px;
  font-family: 'Racama', Arial, Helvetica, sans-serif;
  font-size: 1rem;
  transition: border-color 0.3s ease, color 0.3s ease;
}

.btn-outline:hover {
  border-color: #e8a020;
  color: #ffffff;
}

.calc-wrap {
  max-width: 520px;
  margin: 0 auto;
}

.ohm-triangle-outer {
  text-align: center;
  margin: 40px auto;
  max-width: 280px;
}

.ohm-triangle {
  width: 200px;
  height: 180px;
  clip-path: polygon(50% 0%, 0% 100%, 100% 100%);
  background: #1a1a1a;
  display: flex;
  flex-direction: column;
  margin: 0 auto;
}

.tri-u {
  flex: 1;
  border: none;
  border-bottom: 1px solid #333333;
}

.tri-row {
  flex: 1;
  display: flex;
}

.tri-i {
  flex: 1;
  border: none;
  border-right: 1px solid #333333;
}

.tri-r {
  flex: 1;
  border: none;
}

.tri-zone {
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  color: #e8a020;
  font-size: 2rem;
  font-weight: bold;
  font-family: 'Racama', Arial, Helvetica, sans-serif;
  cursor: pointer;
  width: 100%;
  transition: background 0.2s ease, color 0.2s ease;
}

.tri-zone--active {
  background: #e8a020;
  color: #000000;
}

.tri-hint {
  font-size: 0.8rem;
  color: #555555;
  margin-top: 12px;
}

.net-tabs {
  display: flex;
  gap: 10px;
  margin: 32px 0 8px 0;
}

.net-tab {
  flex: 1;
  background: #111111;
  border: 1px solid #333333;
  color: #888888;
  padding: 10px 24px;
  border-radius: 6px;
  font-family: 'Racama', Arial, Helvetica, sans-serif;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}

.net-tab--active {
  background: #1a1a1a;
  border-color: #e8a020;
  color: #ffffff;
  font-weight: bold;
}

.net-formula {
  font-size: 0.8rem;
  color: #555555;
  margin-bottom: 24px;
}

.field-hint {
  font-size: 0.75rem;
  color: #555555;
  margin-top: 4px;
}

.calc-modes {
  display: flex;
  gap: 10px;
  margin: 32px 0 24px 0;
}

.mode-btn {
  flex: 1;
  background: #111111;
  border: 1px solid #333333;
  color: #888888;
  padding: 10px 24px;
  border-radius: 6px;
  font-family: 'Racama', Arial, Helvetica, sans-serif;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}

.mode-btn--active {
  background: #e8a020;
  border-color: #e8a020;
  color: #000000;
  font-weight: bold;
}

.calc-fields {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.field-group {
  display: flex;
  flex-direction: column;
}

.field-label {
  font-size: 0.85rem;
  color: #888888;
  margin-bottom: 6px;
}

.field-input {
  background: #111111;
  border: 1px solid #333333;
  border-radius: 6px;
  color: #ffffff;
  padding: 12px 16px;
  font-size: 1rem;
  font-family: 'Racama', Arial, Helvetica, sans-serif;
  width: 100%;
  transition: border-color 0.2s ease;
}

.field-input:focus {
  outline: none;
  border-color: #e8a020;
}

.field-input::-webkit-inner-spin-button,
.field-input::-webkit-outer-spin-button {
  -webkit-appearance: none;
}
.field-input[type=number] {
  -moz-appearance: textfield;
  appearance: textfield;
}

.field-error {
  font-size: 0.8rem;
  color: #cc3333;
  margin-top: 4px;
  min-height: 1.1em;
}

.calc-submit {
  margin-top: 24px;
  width: 100%;
  background: #e8a020;
  color: #000000;
  font-weight: bold;
  padding: 14px;
  border-radius: 6px;
  font-size: 1rem;
  font-family: 'Racama', Arial, Helvetica, sans-serif;
  border: none;
  cursor: pointer;
  transition: background 0.3s ease;
}

.calc-submit:hover {
  background: #f0b030;
}

.calc-result {
  background: #111111;
  border: 1px solid #222222;
  border-left: 3px solid #e8a020;
  border-radius: 6px;
  padding: 24px;
  margin-top: 24px;
}

.result-value {
  font-size: 2rem;
  color: #ffffff;
  font-weight: bold;
}

.result-formula {
  font-size: 0.95rem;
  color: #888888;
  margin-top: 8px;
}

.result-desc {
  font-size: 0.85rem;
  color: #666666;
  margin-top: 6px;
}

.block-title {
  font-size: 0.85rem;
  color: #666666;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 12px;
}

.preset-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
}

.preset-btn {
  background: #111111;
  border: 1px solid #222222;
  border-radius: 6px;
  padding: 10px 12px;
  text-align: left;
  cursor: pointer;
  transition: border-color 0.3s ease, background 0.3s ease;
  color: #d0d0d0;
  font-family: 'Racama', Arial, Helvetica, sans-serif;
}

.preset-btn:hover {
  border-color: #444444;
}

.preset-btn--active {
  border-color: #e8a020;
  background: #1a1a1a;
}

.preset-row1 {
  font-size: 0.9rem;
  color: #ffffff;
}

.preset-row2 {
  font-size: 0.8rem;
  color: #666666;
  margin-top: 2px;
}

.section-hr--sm {
  margin: 24px 0;
}

.field-row {
  display: flex;
  gap: 8px;
  align-items: stretch;
}

.field-row .field-input {
  flex: 1;
}

.field-reset-btn {
  background: #1a1a1a;
  border: 1px solid #333333;
  color: #666666;
  width: 42px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 1.2rem;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: color 0.2s ease, border-color 0.2s ease;
}

.field-reset-btn:hover {
  color: #ffffff;
  border-color: #666666;
}

.field-select {
  appearance: none;
  cursor: pointer;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' viewBox='0 0 10 6'%3E%3Cpath d='M0 0l5 6 5-6z' fill='%23666666'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 14px center;
  padding-right: 36px;
}

.field-select option {
  background-color: #111111;
  color: #ffffff;
}


.results-grid {
  display: flex;
  gap: 12px;
  margin-top: 28px;
}

.result-card {
  flex: 1;
  background: #111111;
  border: 1px solid #222222;
  border-top: 3px solid #e8a020;
  border-radius: 6px;
  padding: 20px;
}

.result-card-title {
  font-size: 0.8rem;
  color: #666666;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.result-card-value {
  font-size: 1.8rem;
  color: #ffffff;
  font-weight: bold;
  margin: 8px 0;
}

.result-card-desc {
  font-size: 0.8rem;
  color: #666666;
}

.formulas-block {
  background: #0d0d0d;
  border: 1px solid #1a1a1a;
  border-radius: 6px;
  padding: 16px;
  margin-top: 12px;
}

.formulas-title {
  font-size: 0.8rem;
  color: #555555;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 10px;
}

.formula-line {
  font-size: 0.85rem;
  color: #666666;
  line-height: 1.8;
}

.calc-warning {
  background: #1a0000;
  border: 1px solid #cc3333;
  border-radius: 6px;
  padding: 16px;
  color: #cc3333;
  margin-top: 24px;
}

.section-hr {
  border: none;
  border-top: 1px solid #1a1a1a;
  margin: 40px 0;
}

@media (max-width: 768px) {
  .header-inner {
    flex-direction: column;
    gap: 16px;
  }

  .hero h1 {
    font-size: 1.9rem;
  }

  .cards-grid--3,
  .cards-grid--2,
  .cards-grid--calc {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 600px) {
  .articles-grid {
    grid-template-columns: 1fr;
  }

  .ohm-triangle {
    width: 160px;
    height: 144px;
  }

  .mode-btn,
  .net-tab {
    padding: 8px 14px;
    font-size: 0.85rem;
  }
}

@media (max-width: 480px) {
  .cards-grid--3,
  .cards-grid--2,
  .cards-grid--calc {
    grid-template-columns: 1fr;
  }

  .results-grid {
    flex-direction: column;
  }

  .footer-inner {
    flex-direction: column;
    gap: 12px;
    text-align: center;
  }

  .error-code {
    font-size: 5rem;
  }

  .error-actions {
    flex-direction: column;
    width: 100%;
  }

  .btn-primary--sm,
  .btn-outline {
    width: 100%;
    text-align: center;
  }
}