/* ========================================
   CALCULATOR CLUB - MAIN STYLESHEET
   ======================================== */

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

:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-light: #e0e7ff;
  --secondary: #10b981;
  --danger: #ef4444;
  --warning: #f59e0b;
  --dark: #1f2937;
  --light: #f9fafb;
  --white: #ffffff;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --border-radius: 12px;
  --transition: all 0.3s ease;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background-color: var(--light);
  color: var(--dark);
  line-height: 1.6;
  font-size: 16px;
}

/* ========================================
   HEADER & NAVIGATION
   ======================================== */

header {
  position: sticky;
  top: 0;
  background: var(--white);
  border-bottom: 1px solid var(--gray-200);
  box-shadow: var(--shadow-sm);
  z-index: 100;
}

.header-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

.logo {
  font-size: 24px;
  font-weight: 700;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-decoration: none;
  letter-spacing: -0.5px;
}

nav a {
  color: var(--dark);
  text-decoration: none;
  font-weight: 500;
  font-size: 14px;
  padding: 8px 16px;
  border-radius: 6px;
  transition: var(--transition);
}

nav a:hover {
  color: var(--primary);
  background-color: rgba(99, 102, 241, 0.1);
}

/* ========================================
   MAIN CONTAINER
   ======================================== */

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 20px;
}

/* ========================================
   ADS PLACEHOLDER
   ======================================== */

.ad-placeholder {
  background: var(--gray-200);
  border: 2px dashed var(--gray-400);
  border-radius: var(--border-radius);
  padding: 30px 20px;
  text-align: center;
  color: var(--gray-600);
  font-size: 13px;
  margin: 30px 0;
  font-weight: 500;
  min-height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  word-break: break-word;
}

.ad-placeholder.top {
  margin: 0 0 40px 0;
}

.ad-placeholder.bottom {
  margin: 40px 0 0 0;
}

/* ========================================
   HERO SECTION (Homepage)
   ======================================== */

.hero {
  text-align: center;
  padding: 60px 20px 40px;
}

.hero h1 {
  font-size: clamp(28px, 5vw, 48px);
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 16px;
  letter-spacing: -1px;
}

.hero p {
  font-size: 18px;
  color: var(--gray-600);
  margin-bottom: 32px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
  line-height: 1.8;
}

/* ========================================
   GRID LAYOUT
   ======================================== */

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
  margin: 40px 0;
}

@media (max-width: 768px) {
  .grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }
}

/* ========================================
   CARDS
   ======================================== */

.card {
  background: var(--white);
  border-radius: var(--border-radius);
  padding: 24px;
  box-shadow: var(--shadow-md);
  transition: var(--transition);
  border: 1px solid var(--gray-200);
  cursor: pointer;
}

.card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
  border-color: var(--primary);
}

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

.card-icon {
  font-size: 32px;
  margin-bottom: 16px;
}

.card h3 {
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--dark);
}

.card p {
  font-size: 14px;
  color: var(--gray-600);
  line-height: 1.6;
}

/* ========================================
   FORM STYLES
   ======================================== */

.form-group {
  margin-bottom: 24px;
}

.form-group label {
  display: block;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--dark);
  font-size: 14px;
}

.form-group input,
.form-group select {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--gray-300);
  border-radius: 8px;
  font-size: 16px;
  transition: var(--transition);
  font-family: inherit;
  background-color: var(--white);
  color: var(--dark);
  line-height: 1.5;
}

.form-group input::placeholder {
  color: var(--gray-400);
}

.form-group input[type="date"],
.form-group input[type="time"] {
  cursor: pointer;
}

.form-group input:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

/* ========================================
   BUTTONS
   ======================================== */

.btn {
  padding: 12px 24px;
  border: none;
  border-radius: 8px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: inline-block;
  text-decoration: none;
  text-align: center;
  font-family: inherit;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: var(--white);
  width: 100%;
  margin-right: 8px;
  margin-bottom: 12px;
  transition: var(--transition);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn-secondary {
  background: var(--gray-200);
  color: var(--dark);
  width: 100%;
}

.btn-secondary:hover {
  background: var(--gray-300);
}

.btn-sm {
  padding: 8px 14px;
  font-size: 13px;
  font-weight: 500;
  min-width: auto;
  width: auto;
}

.btn-info {
  background: var(--secondary);
  color: var(--white);
  margin: 0;
}

.btn-info:hover {
  background: #0d9566;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-outline {
  background: transparent;
  color: var(--primary);
  border: 1.5px solid var(--primary);
  margin: 0;
  padding: 7px 12px;
}

.btn-outline:hover {
  background: rgba(99, 102, 241, 0.1);
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

.btn-group {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}

.btn-group .btn {
  flex: 1;
  margin: 0;
  min-width: 120px;
}

@media (max-width: 600px) {
  .btn-group {
    flex-direction: column;
  }

  .btn-group .btn {
    width: 100%;
  }
}

/* ========================================
   RESULT DISPLAY
   ======================================== */

.result-box {
  background: white;
  border: 1px solid var(--gray-300);
  border-radius: var(--border-radius);
  padding: 32px 24px;
  margin: 28px 0;
  display: none;
  animation: slideIn 0.3s ease;
}

.result-box.show {
  display: block;
}

.result-box h3 {
  font-size: 14px;
  color: var(--gray-600);
  margin-bottom: 24px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.8px;
}

.result-box .result-value {
  font-size: 15px;
  font-weight: 400;
  color: var(--gray-700);
  word-break: break-word;
  line-height: 1.8;
  white-space: pre-line;
}

/* Structured result cards */
.result-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 16px;
  margin-top: 24px;
}

.result-card {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.05) 0%, rgba(16, 185, 129, 0.05) 100%);
  border: 1px solid var(--primary-light);
  border-radius: 10px;
  padding: 20px 16px;
  text-align: center;
  transition: var(--transition);
}

.result-card:hover {
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.15);
  transform: translateY(-2px);
}

.result-card-label {
  font-size: 12px;
  color: var(--gray-600);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 8px;
}

.result-card-value {
  font-size: 24px;
  font-weight: 700;
  color: var(--primary);
  word-break: break-word;
  line-height: 1.2;
}

.result-card-unit {
  font-size: 12px;
  color: var(--gray-600);
  margin-top: 4px;
  font-weight: 400;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.error-message {
  color: var(--danger);
  font-size: 14px;
  margin-top: 8px;
  display: none;
}

.error-message.show {
  display: block;
}

/* ========================================
   CALCULATOR LAYOUT
   ======================================== */

.calc-wrapper {
  max-width: 900px;
  margin: 0 auto;
  padding: 40px 20px;
}

.calc-card {
  background: var(--white);
  border-radius: var(--border-radius);
  padding: 40px;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--gray-200);
}

.calc-card h1 {
  font-size: clamp(24px, 5vw, 36px);
  margin-bottom: 16px;
  color: var(--dark);
  letter-spacing: -0.5px;
}

.calc-card .description {
  color: var(--gray-600);
  font-size: 15px;
  margin-bottom: 32px;
  line-height: 1.8;
  font-weight: 500;
}

/* ========================================
   INTERLINKING SECTION
   ======================================== */

.interlinking {
  margin-top: 48px;
  padding: 28px;
  background: var(--light);
  border-radius: var(--border-radius);
  border: 1px solid var(--gray-200);
}

.interlinking h3 {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 16px;
  color: var(--dark);
}

.interlinking-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 12px;
}

.interlinking-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 14px;
  background: var(--white);
  border: 1px solid var(--gray-300);
  border-radius: 6px;
  text-decoration: none;
  color: var(--primary);
  font-weight: 500;
  font-size: 13px;
  transition: var(--transition);
  text-align: center;
  min-height: 40px;
  word-break: break-word;
}

.interlinking-link:hover {
  border-color: var(--primary);
  background: rgba(99, 102, 241, 0.05);
  color: var(--primary-dark);
  transform: translateY(-2px);
}

/* ========================================
   FAQ SECTION
   ======================================== */

.faq {
  margin-top: 48px;
  padding: 28px;
  background: var(--light);
  border-radius: var(--border-radius);
  border: 1px solid var(--gray-200);
}

.faq h3 {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 20px;
  color: var(--dark);
}

.faq-item {
  margin-bottom: 18px;
}

.faq-item h4 {
  font-size: 14px;
  font-weight: 600;
  color: var(--dark);
  margin-bottom: 8px;
  cursor: pointer;
  padding: 10px 12px;
  background: var(--white);
  border-radius: 6px;
  border-left: 3px solid var(--primary);
  transition: var(--transition);
}

.faq-item h4:hover {
  background: rgba(99, 102, 241, 0.05);
}

.faq-item p {
  color: var(--gray-600);
  font-size: 13px;
  line-height: 1.7;
  padding: 0 10px;
  margin-top: 8px;
}

/* ========================================
   FOOTER
   ======================================== */

footer {
  background: var(--dark);
  color: var(--white);
  padding: 40px 20px;
  margin-top: 60px;
}

footer .container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

footer .footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 32px;
  margin-bottom: 32px;
}

footer h4 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 16px;
}

footer a {
  color: #d1d5db;
  text-decoration: none;
  font-size: 14px;
  line-height: 1.8;
  transition: var(--transition);
}

footer a:hover {
  color: var(--white);
}

.footer-divider {
  border-top: 1px solid #374151;
  margin-top: 32px;
  padding-top: 24px;
  text-align: center;
  font-size: 14px;
  color: #9ca3af;
}

/* ========================================
   RESPONSIVE
   ======================================== */

@media (max-width: 768px) {
  .header-container {
    height: 60px;
  }

  .logo {
    font-size: 20px;
  }

  .hero {
    padding: 40px 20px 30px;
  }

  .hero h1 {
    font-size: 28px;
  }

  .hero p {
    font-size: 16px;
  }

  .calc-wrapper {
    max-width: 100%;
    padding: 30px 16px;
  }

  .calc-card {
    padding: 28px 20px;
  }

  .calc-card h1 {
    font-size: 26px;
  }

  .interlinking,
  .faq {
    padding: 24px;
    margin-top: 32px;
  }

  .interlinking h3,
  .faq h3 {
    font-size: 16px;
  }

  .result-cards {
    grid-template-columns: repeat(2, 1fr);
    gap: 14px;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 14px;
  }

  .card {
    padding: 16px;
  }

  .calc-wrapper {
    padding: 20px 12px;
  }

  .calc-card {
    padding: 20px;
    border-radius: 10px;
  }

  .calc-card h1 {
    font-size: 22px;
    margin-bottom: 12px;
  }

  .calc-card .description {
    font-size: 14px;
    margin-bottom: 24px;
  }

  .form-group {
    margin-bottom: 18px;
  }

  .form-group label {
    font-size: 13px;
    margin-bottom: 6px;
  }

  .form-group input,
  .form-group select {
    padding: 10px 12px;
    font-size: 16px;
  }

  .btn-group {
    gap: 8px;
  }

  .btn {
    padding: 10px 16px;
    font-size: 14px;
  }

  .result-box {
    padding: 20px;
    margin: 20px 0;
  }

  .result-box .result-value {
    font-size: 26px;
  }

  .result-cards {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .result-card {
    padding: 16px 12px;
  }

  .result-card-label {
    font-size: 11px;
  }

  .result-card-value {
    font-size: 20px;
  }

  .interlinking,
  .faq {
    padding: 20px;
    margin-top: 24px;
  }

  .interlinking h3,
  .faq h3 {
    font-size: 15px;
    margin-bottom: 12px;
  }

  .interlinking-grid {
    gap: 8px;
  }

  .interlinking-link {
    padding: 8px 12px;
    font-size: 12px;
  }

  .faq-item h4 {
    font-size: 13px;
    padding: 10px;
  }

  .faq-item p {
    font-size: 13px;
  }

  footer .footer-grid {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  footer a {
    font-size: 13px;
  }
}

/* ========================================
   UTILITY CLASSES
   ======================================== */

.mt {
  margin-top: 24px;
}

.mb {
  margin-bottom: 24px;
}

.text-center {
  text-align: center;
}

.text-muted {
  color: var(--gray-600);
}

.text-small {
  font-size: 14px;
}