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

:root {
    --primary: rgb(255, 166, 0);
    --secondary: #d0e22d;
    --gold: #f4c542;
    --bg: #f6f7fb;
    --card: rgba(255, 255, 255, .7);
    --text: #111827;
    --muted: #6b7280;
    --border: rgba(255, 255, 255, .3);
}

body.dark {
    --bg: #000000;
    --card: rgba(0, 0, 0, 0.65);
    --text: #f8fafc;
    --muted: #9ca3af;
    --border: rgba(255, 255, 255, .08);
}

html {
    scroll-behavior: smooth;
}

body {
    /* font-family: 'Inter', sans-serif; */
    background: var(--bg);
    color: var(--text);
    transition: .3s;
    overflow-x: hidden;
}

/* BACKGROUND */

.bg-shape {
    position: absolute;
    border-radius: 50%;
    filter: blur(120px);
    z-index: -2;
}

.shape1 {
    width: 500px;
    height: 500px;
    background: orange;
    top: -200px;
    left: -150px;
    opacity: .25;
}

.shape2 {
    width: 450px;
    height: 450px;
    background: orange;
    bottom: -150px;
    right: -150px;
    opacity: .25;
}

.shape3 {
    width: 500px;
    height: 500px;
    background: orange;
    top: 1500px;
    left: -150px;
    opacity: 0.25;
}

.shape4 {
    width: 450px;
    height: 450px;
    background: orange;
    top: 2250px;
    right: -150px;
    opacity: .05;
}

.shape5 {
    width: 500px;
    height: 500px;
    background: orange;
    top: 3000px;
    left: -150px;
    opacity: .15;
}

.shape6 {
    width: 450px;
    height: 450px;
    background: orange;
    top: 2250px;
    right: -150px;
    opacity: .15;
}

.shape7 {
    width: 500px;
    height: 500px;
    background: orange;
    top: 4500px;
    left: -150px;
    opacity: .05;
}

.shape8 {
    width: 450px;
    height: 450px;
    background: orange;
    top:3650px;
    right: -150px;
    opacity: .15;
}

.shape9 {
    width: 500px;
    height: 500px;
    background: orange;
    top: 6000px;
    left: -150px;
    opacity: .25;
}

.shape10 {
    width: 450px;
    height: 450px;
    background: orange;
    top:6000px;
    right: -150px;
    opacity: .25;
}

/* PARTICLES */

.particles {
    position: fixed;
    inset: 0;
    overflow: hidden;
    pointer-events: none;
    z-index: -1;
}

.particle {
    position: absolute;
    width: 4px;
    height: 4px;
    background: black;
    opacity: .3;
    border-radius: 50%;
    animation: float 10s linear infinite;
}

@keyframes float {
    from {
        transform: translateY(100vh);
    }

    to {
        transform: translateY(-100px);
    }
}

/* HEADER */

header {
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(20px);
    background: rgba(255, 255, 255, .05);
    border-bottom: 1px solid var(--border);
}

.nav {
    max-width: 1200px;
    margin: auto;
    padding: 18px 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.4rem;
    font-weight: 800;
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo-icon {
    width: 38px;
    height: 38px;
    border-radius: 12px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 15px;
}

select,
.toggle {
    background: var(--card);
    border: none;
    color: var(--text);
    padding: 10px 14px;
    border-radius: 14px;
    backdrop-filter: blur(20px);
}

#themeToggle {
    background-color: none;
    transition: all 0.1 ease;
    position: absolute;
    margin-left: -80px;
}

#themeToggle:hover {
    transform: scale(1.1);
    cursor: pointer;
}

#butt-lang {
    transform: scale(1.3);
    transition: all 0.1 ease;
}

#butt-lang:hover {
    transform: scale(1.4);
    cursor: pointer;
}

.btn {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    text-decoration: none;
    padding: 12px 22px;
    border-radius: 14px;
    font-weight: 600;
    transition: .3s;
    box-shadow: 0 15px 40px orange;
}

.btn:hover {
    transform: translateY(-3px);
}

/* HERO */

.hero {
    max-width: 1200px;
    margin: auto;
    padding: 100px 24px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 70px;
    align-items: center;
}

.hero h1 {
    font-size: 4rem;
    line-height: 1.1;
    margin-bottom: 20px;
}

.gradient {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: 1.2rem;
    color: var(--muted);
    margin-bottom: 30px;
}

.hero-buttons {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

.secondary-btn {
    border: 1px solid var(--border);
    padding: 12px 22px;
    border-radius: 14px;
    text-decoration: none;
    color: var(--text);
    backdrop-filter: blur(20px);
}

/* FLASHCARD */

.scene {
    perspective: 1200px;
    display: flex;
    justify-content: center;

    transform: scale(0.8);
    margin-top: 50px;
}

.card3d {
    width: 95%;
    height: 200px;
    position: relative;
    transform-style: preserve-3d;
    animation: flip 5s infinite;
}

@keyframes flip {

    0%,
    45% {
        transform: rotateY(0deg);
    }

    55%,
    100% {
        transform: rotateY(180deg);
    }

    0%,
    45% {
        transform: rotateY(0deg);
    }
}

.side {
    position: absolute;
    inset: 0;
    border-radius: 30px;
    background: var(--card);
    border: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    backface-visibility: hidden;
    background: white;
    box-shadow: 0 20px 60px rgba(0, 0, 0, .15);
}

.back {
    transform: rotateY(180deg);
}

.word {
    font-size: 2.5rem;
    font-weight: 800;
    color: black;
}

.translation {
    margin-top: 10px;
    color: var(--gold);
}

/* PHONE */
.phone-div {
    display: flex;
    flex-direction: column;
    transform: scale(1.2);
    margin-left: 40%;
    transform-style: preserve-3d;
    transition: transform 0.1s;
    perspective: 1000000px;
}

.phone-div h2 {
    margin-top: 50px;
}

.phone{
    width:280px;
    height:560px;

    background-image: url("/assets/pic/demo.png");
    background-repeat: no-repeat;
    background-position: center;
    background-size: 100%;
    padding: 12px;

    border-radius: 40px;
    border: black 10px solid;
    overflow:hidden;

    transform:scale(0.8);

    box-shadow:0 10px 30px orange;
}

.phone img{
    width:100%;
    height:100%;
    object-fit:cover;

    border-radius:20px;
}

.screen {
    height: 100%;
    border-radius: 30px;
    padding: 20px;
    background: linear-gradient(180deg, var(--primary), var(--secondary));
    color: white;
}

.coin {
    background: rgba(255, 255, 255, .15);
    padding: 10px;
    border-radius: 14px;
    margin-top: 15px;
}

/* FEATURES */

section {
    padding: 100px 24px;
}

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

.title {
    text-align: center;
    margin-bottom: 60px;
}

.title h2 {
    font-size: 2.8rem;
}

#vocabEl {
    font-size: 10.8rem;
}

#arrow {
    display: flex;
    justify-content: center;
    font-size: 5.8rem;
}

.grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(260px, 1fr));
    gap: 25px;
}

.grid-steps {
    display: grid;
    grid-template-columns: repeat(3, minmax(260px, 1fr));
    gap: 25px;
}

.grid-steps .step {
    border: #0d1117 1px solid;
}

.grid-steps.show {
    gap: 15px;
}

.step .title-step {
    font-weight: bold;
    font-size: 35px;
}

.step {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.feature {
    padding: 30px;
    border-radius: 24px;
    background: var(--card);
    backdrop-filter: blur(20px);
    border: 1px solid var(--border);
    transition: .3s;

    display: flex;
    flex-direction: row;
    gap: 20px;
}

.imageF {
    transform: scaleY(0);
    transform-origin: top;
    height: 0px;
    transition: transform 0.5s ease-in-out;
}

.featureDiscrabe {
    display: flex;
    gap: 20px;
}

@keyframes showImF {
    0% {
        transform: scaleY(0);
        max-height: 0px;
    }
    100% {
        transform: scaleY(1);
        max-height: 3000px;
    }
}

.featureDiscrabe:hover ~ .imageF,
.featureDiscrabe:hover + .imageF {
  animation: showImF 0.5s ease-in-out 0.3s;
  cursor: pointer;
}

.feature:hover {
    transform: translateY(-8px);
}

.icon {
    font-size: 2rem;
    margin-bottom: 15px;
}

/* STEPS */

.steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 25px;
}

.step {
    text-align: center;
    padding: 40px;
    border-radius: 24px;
    background: var(--card);
}

.step-number {
    width: 55px;
    height: 55px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    margin: auto auto 20px;
    font-weight: 700;
}

/* CTA */

.cta {
    text-align: center;
    padding: 120px 24px;
}

.cta-box {
    max-width: 900px;
    margin: auto;
    padding: 70px;
    border-radius: 35px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
}

.cta h2 {
    font-size: 3rem;
    margin-bottom: 15px;
}

.cta .btn {
    background: white;
    color: orange;
    margin-top: 25px;
}

/* FOOTER */

footer {
    border-top: 1px solid var(--border);
    padding: 40px 24px;
}

.footer {
    max-width: 1200px;
    margin: auto;
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 20px;
}

.links {
    display: flex;
    gap: 18px;
}

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

.fade {
    opacity: 0;
    transform: translateY(30px);
    transition: 1s;
}

.fade.show {
    opacity: 1;
    transform: none;
}

.fadeS {
    opacity: 0;
    transform: translateY(30px);
    transition: 1s;
}

.fadeS.showS {
    opacity: 0.15;
    transform: none;
}


#logo-txt {
    font-family: 'Archivo Black', sans-serif; 
    color: var(--text);
}

/* build in public section — unique classes */

#bip-section {
  padding: 80px 20px;
}

.bip-container {
  max-width: 1100px;
  margin: 0 auto;
}

.bip-title {
  text-align: center;
  margin-bottom: 60px;
}

.bip-title h2 {
  font-size: 42px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 10px;
}

.bip-title p {
  font-size: 18px;
  color: var(--text);
}

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

.bip-step {
  background: var(--card);
  padding: 30px 24px 40px;
  border-radius: 24px;
  box-shadow: 0 8px 30px rgba(0,0,0,0.05);
  text-align: center;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
  position: relative;
}

.bip-step:hover {
  transform: translateY(-8px);
  box-shadow: 0 20px 40px rgba(0,0,0,0.08);
}

.bip-step-number {
  display: inline-block;
  background: var(--bg);
  color: var(--text);
  font-weight: 700;
  font-size: 14px;
  width: 36px;
  height: 36px;
  line-height: 36px;
  border-radius: 50%;
  margin-bottom: 16px;
}

.bip-step-img {
  width: 100%;
  max-height: 180px;
  object-fit: cover;
  border-radius: 16px;
  border: 1px solid #e2e8f0;
  margin-bottom: 20px;
  background: #f1f5f9;
}

.bip-step h3 {
  font-size: 22px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 10px;
}

.bip-step p {
  font-size: 16px;
  color: var(--text);
  line-height: 1.6;
  margin-bottom: 16px;
}

.bip-tag {
  display: inline-block;
  color: var(--text);
  font-size: 13px;
  font-weight: 500;
  padding: 4px 16px;
  border-radius: 30px;
}

#dropdown-lang {
    position: absolute;
    float: left;
    display: flex;
    flex-direction: column;
    margin-top: -10px;
    padding: 10px 20px;
    background: rgba(255, 255, 255, 0.5);
    box-shadow: 0px 0px 30px white;
    border-radius: 10px;


    transform: scale(0.8);
    opacity: 0;
    visibility: hidden; 
    
    transition: opacity 0.3s ease, visibility 0.5s ease, transform 0.5s ease;
}

#dropdown-lang.visible {
    opacity: 1;
    visibility: visible;
    transform: scale(0.8);
}

#dropdown-lang div {
    background: black;
    color: white;
    border-radius: 5px;
    margin-top: 10px;
    padding: 5px 10px;
    font-weight: 700;

    transition: 0.1s ease;
}

#dropdown-lang div:hover {
    transform: scale(1.1);
    cursor: pointer;
}

/* redesign showcase — unique section */

#redesign-showcase {
  padding: 80px 20px;
}

.redesign-container {
  max-width: 1100px;
  margin: 0 auto;
}

.redesign-box {
  background: var(--card);
  padding: 50px 40px 55px;
  border-radius: 40px;
  box-shadow: 0 20px 60px var(--bg);
  text-align: center;
  transition: transform 0.3s ease;
  border: 1px solid var(--bg);
  backdrop-filter: blur(2px);
}

.redesign-badge {
  display: inline-block;
  background: var(--text);
  color: var(--bg);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 2px;
  text-transform: uppercase;
  padding: 6px 18px;
  border-radius: 40px;
  margin-bottom: 20px;
}

.redesign-box h2 {
  font-size: 36px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 12px;
  line-height: 1.2;
}

.redesign-box p {
  font-size: 18px;
  color: var(--text);
  max-width: 540px;
  margin: 0 auto 28px;
  line-height: 1.6;
}

.redesign-image-wrapper {
  position: relative;
  margin: 10px 0 30px;
  border-radius: 24px;
  overflow: hidden;
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.07);
  border: 1px solid #e9edf2;
  background: #f8fafc;
}

#redesign-preview-img {
  width: 100%;
  height: auto;
  display: block;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  background: #eef2f6;
}

.redesign-image-label {
  position: absolute;
  bottom: 16px;
  right: 16px;
  background: rgba(15, 23, 42, 0.75);
  backdrop-filter: blur(4px);
  color: white;
  font-size: 13px;
  font-weight: 500;
  padding: 6px 18px;
  border-radius: 40px;
  letter-spacing: 0.3px;
}

.redesign-btn {
  display: inline-block;
  background: #0f172a;
  color: white;
  font-weight: 600;
  font-size: 18px;
  padding: 16px 44px;
  border-radius: 60px;
  text-decoration: none;
  transition: background 0.2s ease, transform 0.15s ease;
  margin-top: 8px;
}

.redesign-btn:hover {
  background: #1e293b;
  transform: scale(1.02);
}

.redesign-hint {
  font-size: 14px;
  color: #94a3b8;
  margin-top: 14px;
  margin-bottom: 0;
}

/* responsive */
@media (max-width: 640px) {
  .redesign-box {
    padding: 32px 20px 38px;
  }

  .redesign-box h2 {
    font-size: 26px;
  }

  .redesign-box p {
    font-size: 16px;
  }

  .redesign-btn {
    font-size: 16px;
    padding: 14px 32px;
    width: 100%;
  }

  .redesign-image-label {
    font-size: 11px;
    padding: 4px 14px;
    bottom: 10px;
    right: 10px;
  }
}

@media (max-width: 768px) {
  .bip-title h2 {
    font-size: 30px;
  }

  .bip-steps {
    grid-template-columns: 1fr;
    gap: 30px;
  }

  .bip-step {
    padding: 24px 18px 32px;
  }
}

@media(max-width:900px) {
    #logo-txt {
        display: none;
    }
    .hero {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero h1 {
        font-size: 3rem;
    }

    .hero-buttons {
        justify-content: center;
    }

    .grid {
        grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    }

    .grid-steps {
        display: flex;
        flex-direction: column;
    }

    #vocabEl {
        font-size: 3.8rem;
    }

    #arrow {
        font-size: 2.9rem;
    }

    .phone-div {
        transform: scale(1);
        margin-left: 35px;
    }
}