/* ===========================
   VARIABLES
=========================== */
:root{
  --bg:#f1f3f9;
  --text:#1e1f28;
  --brand:#2f6cff;

  --glow1: rgba(47,108,255,.45);
  --glow2: rgba(47,108,255,.25);

  --accent1: rgba(255,140,0,.60);
  --accent2: rgba(255,140,0,.35);

  --divider: rgba(0,0,0,.12);
}

html[data-theme="dark"]{
  --bg:#0e111a;
  --text:#ffffff;
  --brand:#6aa3ff;

  --glow1: rgba(106,163,255,.55);
  --glow2: rgba(106,163,255,.35);

  --accent1: rgba(0,255,160,.65);
  --accent2: rgba(0,255,160,.40);

  --divider: rgba(255,255,255,.15);
}

/* ===========================
   BASE
=========================== */
*{box-sizing:border-box}
html,body{
  height:100%;
  margin:0;
  font-family: system-ui,-apple-system,Segoe UI,Roboto,Arial;
}

body{
  background:
    radial-gradient(circle at center, rgba(47,108,255,.08), transparent 60%),
    var(--bg);
  color:var(--text);
  overflow:hidden;
}

/* ===========================
   LAYOUT
=========================== */
.app{
  height:100%;
  display:flex;
  flex-direction:column;
}

/* ===========================
   HEADER
=========================== */
.top{
  height:80px;
  display:flex;
  justify-content:flex-end;
  align-items:center;
  padding:18px 24px;
  gap:16px;
  border-bottom:1px solid var(--divider);
}

/* ===========================
   TOGGLE
=========================== */
.toggle{
  width:58px;
  height:28px;
  background:#000;
  border-radius:20px;
  position:relative;
  cursor:pointer;
  user-select:none;
}
html[data-theme="dark"] .toggle{ background:#fff; }

.ball{
  width:22px;
  height:22px;
  background:#fff;
  border-radius:50%;
  position:absolute;
  top:3px;
  left:3px;
  transition:.3s;
}
html[data-theme="dark"] .ball{
  background:#000;
  transform:translateX(30px);
}

/* ===========================
   LOGIN BUTTON
=========================== */
.login-btn{
  width:46px;
  height:46px;
  border-radius:50%;
  border:1px solid var(--brand);
  display:grid;
  place-items:center;
  background:transparent;
  cursor:pointer;
  color:var(--brand);
  box-shadow:
    0 0 14px var(--glow2),
    inset 0 0 8px var(--glow2);
  transition:.25s;
}
.login-btn:hover{
  transform:scale(1.12);
  box-shadow:
    0 0 22px var(--glow1),
    0 0 38px var(--glow2);
}
.login-btn svg{
  width:24px;
  height:24px;
  stroke:currentColor;
}

/* ===========================
   CENTER
=========================== */
.center{
  flex:1;
  display:flex;
  flex-direction:column;
  justify-content:center;
  align-items:center;
  text-align:center;
  gap:26px;
}

/* ===========================
   LOGO
=========================== */
.logo{
  width:275px;
  max-width:75vw;
  height:auto;
  filter:
    drop-shadow(0 0 24px var(--glow1))
    drop-shadow(0 0 48px var(--glow2));
  animation: float 4s ease-in-out infinite;
  transition: filter .4s ease, transform .3s ease;
}

.logo:hover,
.center:hover .logo{
  filter:
    drop-shadow(0 0 22px var(--accent1))
    drop-shadow(0 0 45px var(--accent2))
    drop-shadow(0 0 80px var(--accent2));
  transform: scale(1.04);
}

@keyframes float{
  0%,100%{transform:translateY(0)}
  50%{transform:translateY(-12px)}
}

/* ===========================
   TITLE
=========================== */
h1{
  margin:0;
  font-size:70px;
  font-weight:800;
  letter-spacing:.6px;
  color:var(--brand);
  text-shadow:
    0 0 14px var(--glow1),
    0 0 26px var(--glow2),
    0 0 50px var(--glow2);
  transition: text-shadow .4s ease, color .3s ease;
}

.center:hover h1{
  color: var(--accent1);
  text-shadow:
    0 0 12px var(--accent1),
    0 0 24px var(--accent2),
    0 0 48px var(--accent2);
}

.sub{
  font-size:16px;
  letter-spacing:2.4px;
  opacity:.75;
}

/* ===========================
   FOOTER
=========================== */
.bottom{
  position:relative;
  padding:14px 0 18px;
  width:100%;
  text-align:center;
  border-top:1px solid var(--divider);
}

.bottom a{
  color:var(--brand);
  text-decoration:none;
  font-weight:600;
  text-shadow:0 0 12px var(--glow2);
  transition: color .25s ease, text-shadow .35s ease;
}

.bottom a:hover{
  text-decoration:underline;
  color: var(--accent1);
  text-shadow:
    0 0 12px var(--accent1),
    0 0 22px var(--accent2);
}

/* ===========================
   RESPONSIVE
=========================== */
@media (max-width: 900px){
  .logo{ width:240px; }
  h1{ font-size:58px; }
}

@media (max-width: 480px){
  body{ overflow:auto; }

  .top{
    padding:12px 14px;
    height:64px;
  }

  .login-btn{
    width:40px;
    height:40px;
  }

  .toggle{
    width:48px;
    height:24px;
  }

  .ball{
    width:18px;
    height:18px;
  }

  html[data-theme="dark"] .ball{
    transform:translateX(24px);
  }

  .logo{ width:190px; }
  h1{ font-size:42px; }

  .sub{
    font-size:12px;
    letter-spacing:1.6px;
  }

  .center{
    gap:18px;
    padding:18px 0;
  }

  .bottom{ font-size:14px; }
}

/* Focus */
.login-btn:focus-visible,
.toggle:focus-visible,
.bottom a:focus-visible{
  outline: 3px solid rgba(47,108,255,.35);
  outline-offset: 3px;
}