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

:root {
  --bg-main: #f5f7fa;
  --bg-surface: #ffffff;
  --text-main: #1f2d3d;
  --text-muted: #5c6b7a;
  --accent: #0056b3;
  --accent-hover: #004494;
  --border: #d7dee7;
  --shadow-soft: 0 8px 24px rgba(31, 45, 61, 0.08);
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  font-family: "Inter", "Segoe UI", Roboto, Arial, sans-serif;
  background: var(--bg-main);
  color: var(--text-main);
  line-height: 1.6;
}

img {
  max-width: 100%;
  height: auto;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* Layout */
.page-wrapper {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

header {
  background: var(--bg-surface);
  border-bottom: 1px solid #e6ebf1;
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem 0;
}

main {
  flex: 1;
  padding: 2rem 0;
}

/* Calculator area */
.calculator-grid,
.calculators {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.25rem;
}

.calculator,
.calculator-card,
.calculator-container {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  box-shadow: var(--shadow-soft);
  padding: 1.25rem;
}

.calculator h1,
.calculator h2,
.calculator-card h2,
.calculator-container h2 {
  margin-top: 0;
  margin-bottom: 0.8rem;
  color: var(--text-main);
}

.calculator-subtitle,
.description {
  color: var(--text-muted);
  margin-top: 0;
  margin-bottom: 1rem;
}

/* Forms */
.form-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
}

.form-group {
  flex: 1 1 220px;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

label {
  font-weight: 600;
  color: #2e3f51;
}

input,
select,
textarea {
  width: 100%;
  border: 1px solid #bcc8d6;
  border-radius: 10px;
  background: #fff;
  color: var(--text-main);
  padding: 0.7rem 0.8rem;
  font: inherit;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

input:focus,
select:focus,
textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(0, 86, 179, 0.15);
}

input::placeholder,
textarea::placeholder {
  color: #8a98a7;
}

/* Buttons */
button,
.btn,
input[type="submit"] {
  border: 0;
  border-radius: 10px;
  background: var(--accent);
  color: #fff;
  font: inherit;
  font-weight: 600;
  padding: 0.75rem 1rem;
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: 0 4px 6px rgba(0, 86, 179, 0.2);
}

button:hover,
.btn:hover,
input[type="submit"]:hover {
  background: var(--accent-hover);
  box-shadow: 0 6px 12px rgba(0, 86, 179, 0.3);
  transform: translateY(-2px);
}

button:active,
.btn:active,
input[type="submit"]:active {
  transform: translateY(1px);
  box-shadow: 0 2px 4px rgba(0, 86, 179, 0.2);
}

button:focus-visible,
.btn:focus-visible,
input[type="submit"]:focus-visible {
  outline: 3px solid rgba(0, 86, 179, 0.25);
  outline-offset: 2px;
}

/* Results and highlights */
.result,
.output-box,
.summary {
  margin-top: 1rem;
  padding: 0.9rem 1rem;
  border-radius: 10px;
  border-left: 4px solid var(--accent);
  background: #eef5ff;
  color: #12385f;
}

.accent {
  color: var(--accent);
}

/* Tables if used by calculators */
table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 1rem;
  background: #fff;
}

th,
td {
  border: 1px solid #e0e6ee;
  padding: 0.7rem;
  text-align: left;
}

th {
  background: #f3f6fb;
  color: #26374a;
}

/* Footer SEO article area */
footer {
  margin-top: 2rem;
  background: #eef2f7;
  border-top: 1px solid #d8e0ea;
}

.footer-content {
  padding: 2rem 0;
}

.seo-articles,
.footer-articles {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
}

.seo-article,
.footer-article {
  background: #fff;
  border: 1px solid #d6deea;
  border-radius: 12px;
  padding: 1rem;
}

.seo-article h3,
.footer-article h3 {
  margin-top: 0;
  margin-bottom: 0.55rem;
}

.seo-article p,
.footer-article p {
  margin: 0;
  color: var(--text-muted);
}

/* Mobile responsiveness */
@media (max-width: 768px) {
  main {
    padding: 1.25rem 0;
  }

  .header-content {
    flex-direction: column;
    align-items: flex-start;
  }

  .calculator,
  .calculator-card,
  .calculator-container {
    padding: 1rem;
    border-radius: 12px;
  }

  .form-row {
    flex-direction: column;
  }

  button,
  .btn,
  input[type="submit"] {
    width: 100%;
  }

  .footer-content {
    padding: 1.5rem 0;
  }
}