:root {
    --blue: #42b8ee;
    --blue-dark: #136b9d;
    --blue-light: #eaf7ff;
    --white: #ffffff;
    --text: #183142;
    --muted: #61788a;
    --danger: #c73535;
    --shadow: 0 18px 45px rgba(19, 107, 157, 0.14);
}

* { box-sizing: border-box; }

body {
    margin: 0;
    min-height: 100vh;
    font-family: Arial, Helvetica, sans-serif;
    color: var(--text);
    background: linear-gradient(135deg, var(--white), var(--blue-light));
}

a { color: inherit; }

.topbar {
    display: flex;
    justify-content: space-between;
    gap: 24px;
    align-items: center;
    padding: 22px clamp(18px, 5vw, 60px);
    background: rgba(255, 255, 255, 0.86);
    border-bottom: 1px solid rgba(66, 184, 238, 0.25);
    backdrop-filter: blur(10px);
}

.brand { display: flex; align-items: center; gap: 18px; }
.brand img { width: 110px; height: auto; }
.brand h1 { margin: 0 0 4px; font-size: clamp(1.25rem, 2.4vw, 2rem); color: var(--blue-dark); }
.brand p { margin: 0; color: var(--muted); }

nav { display: flex; gap: 10px; flex-wrap: wrap; justify-content: flex-end; }
.nav-link {
    text-decoration: none;
    padding: 11px 16px;
    border-radius: 999px;
    background: var(--blue-light);
    color: var(--blue-dark);
    font-weight: 700;
}
.nav-link.danger { color: var(--danger); background: #fff0f0; }

.container { width: min(1100px, calc(100% - 36px)); margin: 40px auto; }

.hero {
    padding: 34px;
    border-radius: 28px;
    background: var(--white);
    box-shadow: var(--shadow);
    margin-bottom: 28px;
}
.hero h2 { margin: 0 0 8px; color: var(--blue-dark); font-size: clamp(1.8rem, 4vw, 3rem); }
.hero p { margin: 0; color: var(--muted); font-size: 1.1rem; }

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 18px;
}

.link-card {
    display: flex;
    flex-direction: column;
    gap: 10px;
    min-height: 145px;
    padding: 24px;
    border-radius: 24px;
    text-decoration: none;
    background: var(--white);
    border: 1px solid rgba(66, 184, 238, 0.24);
    box-shadow: 0 12px 26px rgba(19, 107, 157, 0.10);
    transition: transform .16s ease, box-shadow .16s ease, border-color .16s ease;
}
.link-card:hover {
    transform: translateY(-4px);
    border-color: var(--blue);
    box-shadow: var(--shadow);
}
.link-title { color: var(--blue-dark); font-size: 1.25rem; font-weight: 800; }
.link-url { color: var(--muted); word-break: break-word; font-size: .95rem; }

.login-page { display: grid; place-items: center; padding: 20px; }
.login-card {
    width: min(430px, 100%);
    background: var(--white);
    border-radius: 30px;
    padding: 34px;
    box-shadow: var(--shadow);
    border: 1px solid rgba(66, 184, 238, 0.24);
}
.logo { width: 160px; display: block; margin: 0 auto 18px; }
.login-card h1 { margin: 0 0 8px; color: var(--blue-dark); text-align: center; }
.login-card p { text-align: center; color: var(--muted); }

form { display: grid; gap: 12px; }
label { font-weight: 700; color: var(--blue-dark); }
input {
    width: 100%;
    padding: 14px 15px;
    border: 1px solid rgba(66, 184, 238, 0.45);
    border-radius: 14px;
    font-size: 1rem;
}
input:focus { outline: 3px solid rgba(66, 184, 238, 0.18); border-color: var(--blue); }
button {
    border: 0;
    border-radius: 14px;
    padding: 14px 18px;
    background: var(--blue);
    color: white;
    font-size: 1rem;
    font-weight: 800;
    cursor: pointer;
}
button:hover { filter: brightness(.96); }
button.secondary { background: var(--blue-light); color: var(--blue-dark); }
.danger-button { color: var(--danger) !important; background: #fff0f0 !important; }

.alert, .success {
    padding: 14px 16px;
    border-radius: 14px;
    margin-bottom: 16px;
    font-weight: 700;
}
.alert { background: #fff0f0; color: var(--danger); }
.success { background: #ecfff3; color: #197a3a; }

.admin-layout { display: grid; gap: 20px; }
.panel {
    background: var(--white);
    border-radius: 24px;
    padding: 24px;
    box-shadow: var(--shadow);
    border: 1px solid rgba(66, 184, 238, 0.24);
}
.panel h2 { margin-top: 0; color: var(--blue-dark); }
.admin-form { max-width: 680px; }
.links-list { display: grid; gap: 12px; }
.link-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 16px;
    border-radius: 16px;
    background: var(--blue-light);
}
.link-row small { color: var(--muted); word-break: break-word; }

@media (max-width: 720px) {
    .topbar { align-items: flex-start; flex-direction: column; }
    nav { justify-content: flex-start; }
    .brand img { width: 90px; }
    .link-row { align-items: flex-start; flex-direction: column; }
}