:root {
  --primary: #5b34eb;
  --accent: #0078ff;
  --dark: #333;
  --muted: #555;
  --bg: #fff;
  --radius-sm: 8px;
  --radius-lg: 30px;
  --transition: 0.3s;
}

* {
  font-family: "Nanum Gothic", sans-serif;
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* Header / Nav */
header {
  background: var(--bg);
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 1000;
  transition: background var(--transition) ease;
}

.header-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 15px 6%;
  width: 100%;
}

#logo-header {
  width: 160px;
  transition: var(--transition);
}
#logo-header:hover {
  transform: scale(1.05);
}

.nav-links-desktop {
  display: flex;
  align-items: center;
  list-style: none;
  flex: 1;
  justify-content: flex-start;
}
.nav-links-desktop li {
  margin: 0 18px;
}
.nav-links-desktop a,
.footer-nav a {
  text-decoration: none;
  color: var(--muted);
  font-weight: 600;
  position: relative;
  transition: color var(--transition) ease;
}
.nav-links-desktop a::after,
.footer-nav a::after {
  content: "";
  position: absolute;
  width: 0;
  height: 2px;
  left: 0;
  bottom: -3px;
  background: linear-gradient(0deg, var(--primary), var(--accent));
  transition: width var(--transition) ease;
}
.nav-links-desktop a:hover,
.footer-nav a:hover {
  background: -webkit-linear-gradient(0deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.nav-links-desktop a:hover::after,
.footer-nav a:hover::after {
  width: 100%;
}

.login-btn-wrapper {
  flex: 1;
  display: flex;
  justify-content: flex-end;
  text-align: right;
}

.login-btn,
.plan-button,
.footer-login-btn {
  background: linear-gradient(90deg, var(--primary), var(--accent));
  color: #fff !important;
  font-weight: 700;
  transition: all var(--transition) ease;
  text-decoration: none;
  display: inline-block;
}
.login-btn {
  padding: 8px 18px;
  border-radius: 6px;
}
.footer-login-btn {
  padding: 12px 30px;
  border-radius: 30px;
  font-size: 1rem;
}
.footer-login-btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 5px 15px rgba(91, 52, 235, 0.3);
}
.login-btn:hover,
.plan-button:hover {
  opacity: 0.9;
}

.menu-toggle {
  display: none;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  width: 40px;
  height: 40px;
  border: none;
  border-radius: 10px;
  font-size: 23px;
  cursor: pointer;
  color: #fff;
  transition: var(--transition);
  z-index: 1002;
  margin-right: 10px;
  transform: rotate(10deg);
  box-shadow: 0 5px 10px rgba(0,0,0,0.1);
}
.menu-toggle.open i {
  transform: rotate(180deg);
}
.menu-toggle.open i::before {
  content: "\f00d";
}

.nav-links-mobile {
  display: none;
  position: fixed;
  top: 0;
  left: -100%;
  width: 70%;
  height: 100vh;
  background: var(--bg);
  box-shadow: 5px 0 25px rgba(0, 0, 0, 0.1);
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 30px;
  transition: left .4s ease;
  list-style: none;
  z-index: 1001;
}
.nav-links-mobile.active {
  left: 0;
  display: flex;
}
.nav-links-mobile li a {
  color: var(--dark);
  font-size: 1.3rem;
  text-decoration: none;
  font-weight: 700;
  transition: color var(--transition) ease;
}
.nav-links-mobile li a:not(.footer-login-btn):hover {
  background: -webkit-linear-gradient(0deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Hero / Call to Action */
#call-message {
  display: flex;
  flex-direction: row;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  min-height: 95vh;
  padding: 140px 6% 60px;
  background: var(--bg);
  color: var(--dark);
  overflow: hidden;
}
.hero-content {
  flex-basis: 45%;
  flex-grow: 0;
  flex-shrink: 1;
  max-width: 550px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  text-align: left;
  z-index: 1;
}
#call-text {
  font-size: 4rem;
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 20px;
  color: var(--dark);
}
#call-text span {
  background: -webkit-linear-gradient(0deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
#description-text {
  font-size: 1.4rem;
  max-width: 500px;
  margin: 0 0 40px 0;
  color: var(--muted);
}
#description-text span {
  font-weight: 800;
  background: -webkit-linear-gradient(0deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.button-container {
  display: flex;
  flex-wrap: wrap;
  gap: 15px;
  justify-content: flex-start;
}
.landing-button {
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 30px;
  border-radius: var(--radius-lg);
  font-size: 1.05rem;
  font-weight: 700;
  transition: all var(--transition) ease;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
  border: 2px solid transparent;
  cursor: pointer;
}
.landing-button:first-child {
  background: linear-gradient(90deg, var(--primary), var(--accent));
  color: #fff;
  border-color: linear-gradient(180deg, var(--primary), var(--accent));
}
.landing-button:first-child:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
}
.landing-button:last-child {
  background: linear-gradient(white, white) padding-box,
            linear-gradient(180deg, var(--primary), var(--accent));
  border: 2px solid transparent;
}
.landing-button:last-child:hover {
  background: linear-gradient(white, white) padding-box,
            linear-gradient(180deg, var(--primary), var(--accent));
  transform: translateY(-3px);
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
}

/* Cellphone / Media */
#cellphone {
  flex-basis: 55%;
  flex-grow: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  z-index: 1;
}
#cellphones-img {
  width: 100%;
  max-width: 750px;
  height: auto;
  display: block;
  object-fit: contain;
  filter: drop-shadow(0 10px 25px rgba(0, 0, 0, 0.15));
}

/* Demonstrations */
.app-demonstration {
  width: 100%;
  padding: 100px 6%;
  overflow: hidden;
}
.demonstration-wrapper {
  display: flex;
  flex-direction: row;
  align-items: center;
  justify-content: space-between;
  gap: 50px;
  max-width: 1200px;
  margin: 0 auto;
}
.demonstration-text {
  flex: 1;
  max-width: 500px;
}
.demonstration-text h2 {
  font-size: 2.8rem;
  font-weight: 800;
  color: var(--dark);
  margin-bottom: 20px;
  line-height: 1.2;
}
.demonstration-text p {
  font-size: 1.2rem;
  color: var(--muted);
  line-height: 1.6;
}

.demonstration-media {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
}
.video-frame {
  width: 100%;
  max-width: 300px;
  border: 10px solid #222;
  border-radius: 40px;
  background: #222;
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.2);
  overflow: hidden;
}
.video-frame video {
  width: 100%;
  height: 100%;
  display: block;
}

#first-demonstration,
#third-demonstration {
  background-color: var(--bg);
}
#second-demonstration .demonstration-wrapper {
  flex-direction: row-reverse;
}
.app-demonstration-gradient {
  background: linear-gradient(90deg, var(--primary), var(--accent));
}
.app-demonstration-gradient .demonstration-text h2,
.app-demonstration-gradient .demonstration-text p {
  color: #fff;
  text-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

/* Subscription / Plans */
#subscription {
  background-color: var(--bg);
  padding: 100px 6%;
}
.subscription-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto 50px auto;
}
.subscription-header h2 {
  font-size: 2.8rem;
  font-weight: 800;
  color: var(--dark);
  margin-bottom: 20px;
}
.subscription-header p {
  font-size: 1.2rem;
  color: var(--muted);
  line-height: 1.6;
}
.subscription-header .price-note {
  font-size: .95rem;
  color: var(--muted);
  margin-top: 15px;
  font-style: italic;
}

#bussines-model {
  display: flex;
  flex-direction: row;
  justify-content: center;
  gap: 30px;
}
.plan-card {
  background: #fff;
  border: 2px solid #e0e0e0;
  border-radius: 12px;
  padding: 35px;
  flex: 1;
  max-width: 450px;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.03);
  transition: transform .3s ease, box-shadow .3s ease;
  display: flex;
  flex-direction: column;
}
.plan-card#premium-plan {
  background: linear-gradient(white, white) padding-box,
            linear-gradient(180deg, var(--primary), var(--accent));
  border: 2px solid transparent;
  box-shadow: 0 10px 30px rgba(91, 52, 235, 0.1);
}
.plan-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.08);
}
.plan-card h3 {
  font-size: 1.5rem;
  font-weight: 800;
  width: fit-content;
  background: -webkit-linear-gradient(0deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 15px;
}
.plan-card .description {
  font-size: 1rem;
  color: var(--muted);
  line-height: 1.5;
  min-height: 40px;
}

.plan-price {
  margin-top: 20px;
  margin-bottom: 25px;
}
.plan-price .price-value {
  font-size: 2.8rem;
  font-weight: 800;
  color: var(--dark);
  margin-right: 5px;
}
.plan-price .price-period {
  font-size: 1.1rem;
  color: var(--muted);
}

.plan-button {
  display: block;
  width: 100%;
  padding: 14px 20px;
  border-radius: 30px;
  text-align: center;
  text-decoration: none;
  font-weight: 700;
  font-size: 1.05rem;
  margin-top: auto;
  transition: all var(--transition) ease;
}
.plan-button.dark-button {
  background: #333;
  color: #fff;
}
.plan-button.dark-button:hover {
  background: #000;
  opacity: 1;
  transform: scale(1.02);
}
.plan-button:hover {
  transform: scale(1.02);
}

.advantages-list {
  list-style: none;
  padding: 0;
  margin-top: 30px;
}
.advantages-item {
  display: flex;
  align-items: flex-start;
  margin-bottom: 15px;
  gap: 12px;
  flex-wrap: wrap;
}
.advantages-item i {
  font-size: 1.2rem;
  margin-top: 3px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-emphasis-color: transparent;
}
.advantages-item .advantage {
  font-size: 1rem;
  color: var(--dark);
  line-height: 1.5;
  flex: 1;
  min-width: 150px;
}
.ex-list {
  list-style: disc;
  padding-left: 20px;
  margin-top: 10px;
  flex-basis: 100%;
  margin-left: 32px;
}
.ex {
  font-size: .95rem;
  color: var(--muted);
  margin-bottom: 8px;
}

/* FAQ */
#FAQ {
  background-color: var(--bg);
  padding: 100px 6%;
}
.faq-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto 50px auto;
}
.faq-header h2 {
  font-size: 2.8rem;
  font-weight: 800;
  color: var(--dark);
  margin-bottom: 20px;
}
.faq-header p {
  font-size: 1.2rem;
  color: var(--muted);
  line-height: 1.6;
}

.faq-container {
  display: flex;
  flex-direction: row;
  gap: 40px;
  max-width: 1200px;
  margin: 0 auto;
}
.faq-category-nav {
  flex: 0 0 300px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.faq-category-btn {
  display: flex;
  align-items: center;
  gap: 15px;
  padding: 20px;
  border: 2px solid #f0f0f0;
  border-radius: 12px;
  background: #f8f8f8;
  color: var(--dark);
  font-size: 1.1rem;
  font-weight: 700;
  cursor: pointer;
  text-align: left;
  transition: all var(--transition) ease;
}
.faq-category-btn i {
  font-size: 1.3rem;
  color: var(--primary);
  transition: all var(--transition) ease;
}
.faq-category-btn:hover {
  background: #fff;
  border-color: #ddd;
}
.faq-category-btn.active {
  background: linear-gradient(white, white) padding-box,
            linear-gradient(0deg, var(--primary), var(--accent));
  border: 2px solid transparent;
  box-shadow: 0 5px 20px rgba(91, 52, 235, 0.1);
  color: var(--primary);
}
.faq-category-btn.active i {
  transform: scale(1.1);
}

.faq-content {
  flex: 1;
}
.faq-category-content {
  display: none;
}
.faq-category-content.active {
  display: block;
}
.faq-item {
  border-bottom: 1px solid #f0f0f0;
}
.faq-item:last-child {
  border-bottom: none;
}
.faq-question {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 0;
  cursor: pointer;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--dark);
}
.faq-question i {
  font-size: 1rem;
  color: var(--primary);
  transition: transform .3s ease;
}
.faq-answer {
  max-height: 0;
  overflow: hidden;
  padding: 0 10px;
  transition: max-height .3s ease-out, padding .3s ease-out;
}
.faq-answer p {
  font-size: 1rem;
  color: var(--muted);
  line-height: 1.6;
  padding-bottom: 20px;
}
.faq-item.active .faq-answer {
  max-height: 300px;
  padding: 0 10px;
}
.faq-item.active .faq-question i {
  transform: rotate(180deg);
}

/* Footer */
footer {
  background-color: var(--bg);
  color: var(--dark);
  padding: 80px 6%;
  margin-top: 100px;
  border-top: 1px solid #e0e0e0;
}
.footer-content-wrapper {
  display: flex;
  flex-direction: row;
  justify-content: space-between;
  gap: 40px;
  max-width: 1200px;
  margin: 0 auto;
}
.footer-left {
  flex-basis: 35%;
}
#logo-footer {
  width: 250px;
  margin-bottom: 20px;
}
.footer-copyright {
  font-size: .9rem;
  color: var(--muted);
  line-height: 1.5;
}
.footer-right {
  flex-basis: 60%;
  display: flex;
  flex-direction: row;
  justify-content: space-between;
  gap: 30px;
}
.footer-column {
  flex: 1;
}
.footer-section-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 20px;
}
.footer-nav ul {
  list-style: none;
  padding: 0;
}
.footer-nav li {
  margin-bottom: 12px;
}

/* Responsive */
@media (max-width: 820px) {
  .header-nav {
    padding: 10px 4%;
  }
  .nav-links-desktop,
  .login-btn-wrapper {
    display: none;
  }
  .menu-toggle {
    display: block;
    order: 3;
  }
  #logo-header {
    order: 1;
    width: 140px;
    flex: none;
  }
  .menu-toggle i {
    color: white;
  }
  #call-message {
    flex-direction: column;
    height: auto;
    min-height: 90vh;
    padding: 100px 4% 40px;
    text-align: center;
  }
  .hero-content {
    max-width: 100%;
    align-items: center;
    text-align: center;
    order: 1;
    flex-basis: auto;
  }
  #cellphone {
    max-width: 100%;
    order: 2;
    margin-top: 40px;
    flex-basis: auto;
  }
  #cellphones-img {
    margin-left: 20%;
    max-width: 320px;
    filter: drop-shadow(0 10px 20px rgba(0, 0, 0, 0.2));
  }
  #call-text {
    font-size: 2.8rem;
    margin-bottom: 15px;
  }
  #description-text {
    font-size: 1.1rem;
    margin: 0 auto 30px auto;
  }
  .button-container {
    flex-direction: row;
    width: 100%;
    gap: 10px;
    justify-content: center;
  }
  .landing-button {
    width: auto;
    padding: 12px 20px;
    font-size: .9rem;
  }
  .demonstration-wrapper {
    flex-direction: column !important;
    gap: 40px;
  }
  .demonstration-text {
    max-width: 100%;
    text-align: center;
    align-items: center;
  }
  .demonstration-text h2 {
    font-size: 2.2rem;
  }
  .demonstration-text p {
    font-size: 1.1rem;
  }
  .video-frame {
    max-width: 260px;
  }
  #second-demonstration .demonstration-text {
    order: 1;
  }
  #second-demonstration .demonstration-media {
    order: 2;
  }
  .subscription-header h2 {
    font-size: 2.2rem;
  }
  #bussines-model {
    flex-direction: column;
    gap: 20px;
  }
  .plan-card {
    max-width: 100%;
  }
  .plan-card .description {
    min-height: auto;
  }
  .faq-container {
    flex-direction: column;
    gap: 20px;
  }
  .faq-category-nav {
    flex: 1;
    flex-direction: row;
    overflow-x: auto;
    padding-bottom: 20px;
  }
  .faq-category-nav::-webkit-scrollbar {
    height: 8px;
  }
  .faq-category-nav::-webkit-scrollbar-track {
    background: #f0f0f0;
    border-radius: 4px;
  }
  .faq-category-nav::-webkit-scrollbar-thumb {
    background: linear-gradient(90deg, var(--primary), var(--accent));
    border-radius: 4px;
  }
  .faq-category-nav::-webkit-scrollbar-thumb:hover {
    opacity: .8;
  }
  .faq-category-btn {
    flex-direction: column;
    justify-content: center;
  }
  .faq-category-btn i {
    margin-bottom: 10px;
  }
  .faq-content {
    flex: 1;
  }
  .footer-content-wrapper {
    flex-direction: column;
    gap: 40px;
  }
  .footer-left {
    text-align: center;
  }
  .footer-right {
    flex-direction: column;
    gap: 30px;
    text-align: center;
  }
  .footer-login-btn {
    padding: 14px 40px;
  }
}