input[type=number]::-webkit-inner-spin-button, 
input[type=number]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

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

html, body {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

  body {
    background-color: #f9f4e0;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    height: calc(var(--vh, 1vh) * 100);
  }

/* Navbar Styles */
.navbar {
  width: 100%;
  padding: 1rem 1rem;
  background: rgba(255, 255, 255, 0.2);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.15);
  top: 0;
  left: 0;
  z-index: 100;
  display: flex;
  justify-content: space-between;
  align-items: center;
  background-color: #FCE6B3;
  height: calc(var(--vh) * 10);
}

.container-wrapper{
  height: calc(var(--vh) * 90);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 90%;
}

.container {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 3rem;
  width: 100%;
  padding: 0 4vh;
  text-align: center;
}



.box {
  display: flex;
  flex-direction: column;   /* stack items vertically */
  justify-content: center;  /* center vertically */
  align-items: center;      /* center horizontally */
  text-align: center;       /* align text inside each child */
  backdrop-filter: blur(12px);
  background: rgba(255, 255, 255, 0.25);
  border-radius: 20px;
  font-size: 2rem;
  font-weight: 600;
  cursor: pointer;
  position: relative;
  text-decoration: none;
  height: 30vh;
  color: #ffffff;
  box-shadow: 0 8px 32px rgba(31, 38, 135, 0.2);
  transition: all 0.3s ease;
  border: 1px solid rgba(255, 255, 255, 0.3);
} 


/* Animated Gradient Overlay */
.box::before {
  content: '';
  background: radial-gradient(circle at center, rgba(255,255,255,0.15), transparent 70%);
  pointer-events: none;
  transition: opacity 0.3s ease;
  opacity: 0;
}

.box:hover::before {
  opacity: 1;
}

.box:hover {
  transform: translateY(-6px) scale(1.02);
  box-shadow: 0 12px 24px rgba(31, 38, 135, 0.25);
} 

/* Individual Colors */
.add {
  background: linear-gradient(135deg, #96d14d, #56ab2f);
}

.subtract {
  background: linear-gradient(135deg, #ff6a6a, #d62e2e);
}

.multiply {
  background: linear-gradient(135deg, #667eea, #764ba2);
}

.divide {
  background: linear-gradient(135deg, #f7971e, #e28d25);
}



.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: #333;
}

.back-link {
  text-decoration: none;
  font-weight: 600;
  font-size: 1.5rem;
  color: #333;
  transition: color 0.3s ease;
}

.back-link:hover {
  color: #000;
}


.nav-links {
  list-style: none;
  display: flex;
  gap: 1.5rem;
}

.nav-links li a {
  text-decoration: none;
  color: #333;
  font-weight: 500;
  padding: 0.5rem;
  border-radius: 8px;
  transition: background 0.3s ease, color 0.3s ease;
}

.nav-links li a:hover {
  background-color: rgba(255, 255, 255, 0.3);
  color: #000;
}



/* Page Section Styles */
.section-container {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 2rem;
  height: calc(var(--vh) * 90);
} 

/* Learn & Practice Boxes */
 .options {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  /* justify-content: center;
  align-items: center; */
  gap: 3rem;
  width: 100%;
} 

.option {
  padding: 2rem 3rem;
  font-size: 1.8rem;
  font-weight: 600;
  text-decoration: none;
  border-radius: 12px;
  color: white;
  transition: transform 0.2s ease, box-shadow 0.3s ease;
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.1);
  backdrop-filter: blur(10px);
  text-align: center;
  text-shadow: 1px 1px 2px rgba(0,0,0,0.6);
  width: 100%; 
  min-height: 12rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.option2 { background: linear-gradient(135deg, #197347, #137a48); } /* coral pink */
.option1 { background: linear-gradient(135deg, #fd9502, #ff9204); }
.option3 { background: linear-gradient(135deg, #5c1ba1, #5722b4); }
.option5 { background: linear-gradient(135deg, #039fce, #0792ae); } /* pastel purple-pink */
.option4 { background: linear-gradient(135deg, #d11808, #ad110b); } /* sunset tones */



.option1, .option2, .option3,.option4, .option5, .option6{
  min-height: 9rem;
  width: 100%;
}

.options > *:nth-child(odd):last-child {
  grid-column: 1 / -1;
  justify-self: center;  /* center within that span */
  width: 50%;
  min-width: calc((100% - var(--gap)) / 2) !important
}

.learn {
  background: linear-gradient(135deg, #158037, #219c48); /* deep teal/navy */
}

.basic {
  background: linear-gradient(135deg, rgb(218, 56, 56), #d64354); /* dark red → crimson */
}

.practice {
  background: linear-gradient(135deg, #296898, #2c82b7); /* purple shades */
}




.option:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.15);
}


.language-select {
  font-family: 'Poppins', sans-serif;
  display: flex;
  align-items: center;
  gap: 8px;
  background-color: hsl(210, 70%, 74%);
  padding: 6px 10px;
  border-radius: 6px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.05);
  margin-left: auto;
  margin-right: 1rem;
}

.lang-box{
  display: flex;
  align-items: center;
}

.language-select label {
  font-size: 1rem;
  color: #374151;
  font-weight: 500;
}

.language-select select {
  font-size: 1rem;
  padding: 6px 10px;
  border: 1px solid #cbd5e1;
  border-radius: 6px;
  background-color: white;
  color: #111827;
  outline: none;
} 

.language-select select:focus {
  border-color: #22c55e; /* Tailwind's green-500 */
  box-shadow: 0 0 0 3px rgba(34, 197, 94, 0.3);
}

.subsymbol {
  font-size: 1.5rem; /* adjust size as needed */
  display: block;
  text-align: center;
  color: #f0f0f0; /* or any color you want */
  margin-top: 5px;
}


/* Responsive Adjustments */
@media (max-width: 1024px) {
  .navbar{
    height: calc(var(--vh) * 10);
  }
  .container-wrapper {
    height: calc(var(--vh) * 90);
    display: flex;
    align-items: center;
    justify-content: center;
    width:90%;
  }
  
  .container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center; 
    gap: 2vh;
    padding: 0;
    width: 100%;
  }

   .nav-links {
    display: none;
  }

  .option{
    padding: 1.5rem 2rem;
  }

  .options {
    display: flex;
    flex-direction: column;
    justify-content: space-evenly;
    align-items: center;
    height: 100%;
}

.options > *:nth-child(odd):last-child {
  width: 100%;
}

  .language-select {
      flex-direction: row;
      align-items: center;
      margin: 0.5rem auto 0.5rem auto;
      gap: 4px;
      padding: 6px 12px;
      width: fit-content;
}
.language-select label {
  font-size: 0.9rem;
}
.language-select select {
  font-size: 0.9rem;
  padding: 5px 10px;
  width: 100%;
}
.lang-box{
  display: flex;
  align-items: flex-end;
}
}

@media (min-width: 300px) and (max-width: 650px) and (min-height: 600px) and (max-height: 1120px){
  .navbar{
    padding: 0.5rem 0.5rem;
    font-size: 1.2rem;
  }
  .container {
    gap: 4vh;
    padding: 0; 
    box-sizing: border-box; 
    width: 100%;
    max-width: 100%;
  }

  .box {
    font-size: 1.5rem;
    height: 15vh;
    width: 65%;
    max-width: 100%; 
  }

  .logo{
    font-size: 1.4rem !important;
  }


.language-select label {
  font-size: 0.8rem;
}

.language-select select {
  font-size: 0.8rem;
} 
.option{
  min-height: 8vh;
  font-size: 1.3rem !important;
  width: 100%;
}

.options{
  gap: 0.5rem;
}

.back-link {
  font-size: 1.3rem;
}

.section-container {
  width: 90%;
}

.option1, .option2, .option3,.option4, .option5, .option6{
  font-size: 2rem;
  min-height: 3vh;
}

}

/* iphone SE, Samsung Galaxy s8+ */
@media (min-height: 667px) and (max-height: 740px) and (min-width: 360px) and (max-width: 539px){
  .navbar{
    padding: 0.5rem 0.5rem;
    font-size: 1.2rem;
  }
  .container {
    gap: 4vh;
    padding: 0; 
    box-sizing: border-box; 
    width: 100%;
    max-width: 100%;
  }

  .box {
    font-size: 1.5rem;
    height: 15vh;
    width: 65%;
    max-width: 100%; 
  }

  .logo{
    font-size: 1.4rem !important;
  }


.language-select label {
  font-size: 0.8rem;
}

.language-select select {
  font-size: 0.8rem;
} 
.option{
  min-height: 8vh;
  font-size: 1.3rem !important;
  width: 100%;
}

.options{
  gap: 0.5rem;
}

.back-link {
  font-size: 1.3rem;
}

.section-container {
  width: 90%;
}

.option1, .option2, .option3,.option4, .option5, .option6{
  font-size: 2rem;
  min-height: 3vh;
}
}

/* surface duo  */
@media (min-height: 667px) and (max-height: 740px) and (min-width: 540px){
  .navbar{
    padding: 0.5rem 0.5rem;
    font-size: 1.2rem;
  }
  .container {
    gap: 4vh;
    padding: 0; 
    box-sizing: border-box; 
    width: 100%;
    max-width: 100%;
  }

  .box {
    font-size: 1.6rem;
    height: 15vh;
    width: 65%;
    max-width: 100%; 
  }

  .logo{
    font-size: 1.6rem;
  }


.language-select label {
  font-size: 0.8rem;
}

.language-select select {
  font-size: 0.8rem;
} 
.option{
  min-height: 10vh;
  font-size: 1.2rem !important;
  width: 100%;
}

.options{
  gap: 0.5rem;
}

.back-link {
  font-size: 1.3rem;
}

.section-container {
  width: 80%;
}

.option1, .option2, .option3,.option4, .option5, .option6{
  font-size: 2rem;
  min-height: 5vh;
}

}

/* iphone 12 pro, pixel 7, Samsung Galaxy s20 ultra */
@media (min-height: 844px) and (max-height: 932px) and (min-width: 390px) and (max-width: 413px){
  .navbar{
    padding: 0.5rem 0.5rem;
    font-size: 1.4rem;
  }
  .container {
    gap: 4vh;
    padding: 0; 
    box-sizing: border-box; 
    width: 100%;
    max-width: 100%;
  }

  .box {
    font-size: 1.4rem;
    height: 15vh;
    width: 70%;
    max-width: 100%; 
  }

  .logo{
    font-size: 1.4rem;
  }


.language-select label {
  font-size: 1rem;
}

.language-select select {
  font-size: 1rem;
} 

.option{
  min-height: 12vh;
  font-size: 1.3rem !important;
  width: 100%;
}

.options{
  gap: 0.5rem;
}

.back-link {
  font-size: 1.2rem;
}

.section-container {
  width: 90%;
}

.option1, .option2, .option3,.option4, .option5, .option6{
  min-height: 3vh;
  font-size: 2rem;
}
}

/* iphone xr, iphone 14 pro max,  */
@media (min-height: 844px) and (max-height: 932px) and (min-width: 414px) {
  .navbar{
    padding: 0.5rem 0.5rem;
    font-size: 1.4rem;
  }
  .container {
    gap: 4vh;
    padding: 0; 
    box-sizing: border-box; 
    width: 100%;
    max-width: 100%;
  }

  .box {
    font-size: 1.6rem;
    height: 15vh;
    width: 70%;
    max-width: 100%; 
  }

  .logo{
    font-size: 1.6rem;
  }


.language-select label {
  font-size: 1rem;
}

.language-select select {
  font-size: 1rem;
} 

.option{
  min-height: 10vh;
  font-size: 1.3rem !important;
  width: 100%;
}

.options{
  gap: 0.5rem;
}

.back-link {
  font-size: 1.4rem;
}

.section-container {
  width: 90%;
}

.option1, .option2, .option3,.option4, .option5, .option6{
  font-size: 2rem;
  min-height: 5vh;
}
}

/* ipad, surface pro 7, Asuz zenbook fold */
@media (min-height: 933px) and (max-height: 1368px) and (min-width: 360px) and (max-width: 1024px){
  .navbar{
    padding: 1rem 1rem;
    font-size: 2.3rem !important;
  }
  .container {
    gap: 6vh;
    padding: 0; 
    box-sizing: border-box; 
    width: 100%;
    max-width: 100%;
  }

  .box {
    font-size: 2.3rem !important;
    height: 14vh;
    width: 60%;
    max-width: 100%; 
  }
  .logo{
    font-size: 2.2rem !important;
  }


.language-select label {
  font-size: 1.5rem;
}

.language-select select {
  font-size: 1.5rem;
} 

.option{
  min-height: 10vh;
  font-size: 2.1rem !important;
  width: 100%;
}

.options{
  gap: 0.5rem;
  width: 80%;
}

.back-link {
  font-size: 1.6rem;
}

.section-container {
  width: 80%;
}
.option1,.option2,.option3,.option4,.option5,.option6{
  font-size: 2rem;
  min-height: 5vh;
}
}