/* EulerNetwork Learning Center - fresh/minimal theme */

:root {
    --page-bg: linear-gradient(160deg, #ecfdf5 0%, #f0fdfa 40%, #e0f2fe 100%);
    --accent: #10b981;
    --accent-soft: #34d399;
    --accent-grad: linear-gradient(135deg, #34d399, #22d3ee);
    --pastel-deep: #6ee7b7;
    --pastel-mid: #a7f3d0;
    --pastel-light: #d1fae5;
    --card-bg: rgba(255, 255, 255, 0.78);
    --card-border: rgba(16, 185, 129, 0.18);
    --text-strong: #0f4c3a;
    --text-body: #3b6b5c;
    --text-muted: #6b9184;
    --glass-blob: rgba(52, 211, 153, 0.28);
}

*, *::before, *::after {
    box-sizing: border-box;
}

body {
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    -webkit-tap-highlight-color: transparent;
    background: var(--page-bg) fixed;
    line-height: 1.6;
}

/* ---------- decorative blobs ---------- */
.blob {
    position: fixed;
    border-radius: 50%;
    background: var(--glass-blob);
    filter: blur(60px);
    pointer-events: none;
    z-index: 0;
}
.blob-1 {
    width: 380px; height: 380px;
    top: -80px; left: -80px;
    background: var(--glass-blob);
}
.blob-2 {
    width: 460px; height: 460px;
    bottom: -120px; right: -100px;
    background: var(--glass-blob);
}
.blob-3 {
    width: 260px; height: 260px;
    top: 40%; left: 60%;
    background: color-mix(in srgb, var(--glass-blob) 60%, transparent);
}

/* ---------- toolbar ---------- */
.toolbar {
    position: sticky;
    top: 0;
    z-index: 50;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    background: color-mix(in srgb, var(--card-bg) 60%, transparent);
    border-bottom: 1px solid var(--card-border);
    padding-top: env(safe-area-inset-top);
}
.toolbar-inner {
    max-width: 85rem;
    margin: 0 auto;
    padding: 0.9rem 1.25rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}
.toolbar-brand {
    display: flex;
    align-items: center;
    gap: 0.6rem;
}
.brand-pill {
    font-weight: 800;
    font-size: 0.95rem;
    color: #fff;
    padding: 0.35rem 0.8rem;
    border-radius: 9999px;
    background: var(--accent-grad);
    box-shadow: 0 4px 14px var(--glass-blob);
    letter-spacing: 0.02em;
}
.brand-text {
    font-size: 0.9rem;
    color: var(--text-body);
    font-weight: 600;
}
.toolbar-actions {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

/* segmented language toggle */
.seg {
    display: inline-flex;
    background: color-mix(in srgb, var(--card-bg) 70%, transparent);
    border: 1px solid var(--card-border);
    border-radius: 9999px;
    padding: 3px;
    gap: 2px;
}
.seg-btn {
    border: none;
    background: transparent;
    color: var(--text-muted);
    font-weight: 600;
    font-size: 0.85rem;
    padding: 0.3rem 0.9rem;
    border-radius: 9999px;
    cursor: pointer;
    transition: all 0.25s ease;
}
.seg-btn.active {
    background: var(--accent-grad);
    color: #fff;
    box-shadow: 0 3px 10px var(--glass-blob);
}

/* theme switcher */
.theme-switcher {
    position: relative;
}
.theme-toggle {
    display: inline-flex;
    align-items: center;
    gap: 0.45rem;
    border: none;
    background: color-mix(in srgb, var(--card-bg) 70%, transparent);
    color: var(--text-body);
    border: 1px solid var(--card-border);
    padding: 0.45rem 0.9rem;
    border-radius: 9999px;
    font-weight: 600;
    font-size: 0.85rem;
    cursor: pointer;
    transition: all 0.25s ease;
}
.theme-toggle:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px var(--glass-blob);
}
.theme-toggle-text { line-height: 1; }
.theme-toggle svg { opacity: 0.6; }

.swatch {
    width: 16px;
    height: 16px;
    border-radius: 50%;
    display: inline-block;
    box-shadow: inset 0 0 0 1px rgba(255,255,255,0.4);
}

.theme-menu {
    position: absolute;
    right: 0;
    top: calc(100% + 10px);
    min-width: 190px;
    background: #fff;
    border: 1px solid var(--card-border);
    border-radius: 18px;
    padding: 0.9rem;
    box-shadow: 0 18px 45px -18px rgba(0,0,0,0.22);
    display: none;
    z-index: 60;
}
.theme-menu.open { display: block; animation: menuPop 0.22s ease; }
@keyframes menuPop {
    from { opacity: 0; transform: translateY(-6px) scale(0.97); }
    to { opacity: 1; transform: translateY(0) scale(1); }
}
.theme-menu-title {
    font-size: 0.7rem;
    font-weight: 700;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    padding: 0.3rem 0.4rem;
}
.theme-menu-hint { text-transform: none; letter-spacing: 0; font-weight: 500; }
.theme-item {
    display: flex;
    align-items: center;
    gap: 0.7rem;
    width: 100%;
    border: none;
    background: transparent;
    padding: 0.5rem 0.6rem;
    border-radius: 12px;
    cursor: pointer;
    color: var(--text-body);
    font-weight: 500;
    font-size: 0.88rem;
    transition: background 0.2s ease;
    text-align: left;
}
.theme-item:hover { background: var(--pastel-light); }
.theme-item.active { background: var(--pastel-mid); color: var(--text-strong); font-weight: 600; }

/* ---------- main layout ---------- */
.main {
    position: relative;
    z-index: 1;
    max-width: 70rem;
    margin: 0 auto;
    padding: 3rem 1.25rem 7rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2.5rem;
}

.card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border-radius: 28px;
    box-shadow: 0 24px 50px -28px rgba(0,0,0,0.18);
    width: 100%;
}

/* ---------- unlock / landing ---------- */
.unlock-wrap {
    max-width: 34rem;
    padding: 3rem 2rem;
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
}
.hero-title {
    font-size: clamp(2rem, 5vw, 2.8rem);
    font-weight: 800;
    letter-spacing: 0.06em;
    color: transparent;
    background: var(--accent-grad);
    -webkit-background-clip: text;
    background-clip: text;
    margin: 0 0 0.75rem;
}
.hero-sub {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-muted);
    margin: 0 0 2rem;
}
.unlock-code {
    display: inline-flex;
    align-items: center;
    gap: 0.7rem;
    background: var(--pastel-light);
    border: 1px solid var(--card-border);
    border-radius: 9999px;
    padding: 0.6rem 1.1rem;
    color: var(--text-body);
    font-size: 0.85rem;
    margin-bottom: 2.25rem;
    flex-wrap: wrap;
    justify-content: center;
}
.code-pill {
    font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
    font-weight: 700;
    color: var(--accent);
    background: #fff;
    padding: 0.2rem 0.6rem;
    border-radius: 9999px;
    border: 1px solid var(--card-border);
}
.unlock-btn {
    border: none;
    background: transparent;
    cursor: pointer;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.9rem;
    color: var(--text-body);
    font-family: inherit;
    transition: transform 0.3s ease;
}
.unlock-btn:hover { transform: translateY(-2px); }
.unlock-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 72px;
    height: 72px;
    border-radius: 50%;
    background: var(--pastel-mid);
    border: 2px solid var(--pastel-deep);
    color: var(--accent);
    box-shadow: 0 8px 22px var(--glass-blob);
}
.unlock-text {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-body);
    letter-spacing: 0.06em;
}

/* ---------- intro / steps ---------- */
.intro-card {
    max-width: 46rem;
    padding: 2.5rem 2rem;
}
.intro-title {
    font-size: clamp(1.6rem, 4vw, 2.2rem);
    font-weight: 800;
    margin: 0 0 0.4rem;
    color: var(--text-strong);
}
.gradient-text {
    color: transparent;
    background: var(--accent-grad);
    -webkit-background-clip: text;
    background-clip: text;
}
.muted { color: var(--text-muted); }
.intro-card .muted { margin: 0; font-size: 0.95rem; }

.steps {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
    gap: 0.9rem;
    margin-top: 0.75rem;
}
.step {
    position: relative;
    display: flex;
    align-items: center;
}
.step-num {
    position: absolute;
    left: -8px;
    top: -9px;
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background: var(--accent-grad);
    color: #fff;
    font-size: 0.72rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2;
    box-shadow: 0 3px 8px var(--glass-blob);
}
.select-control {
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    min-width: 10.5rem;
    background: #fff;
    border: 1.5px solid var(--pastel-deep);
    color: var(--text-strong);
    font-family: inherit;
    font-weight: 500;
    font-size: 0.9rem;
    padding: 0.8rem 2.4rem 0.8rem 1rem;
    border-radius: 14px;
    cursor: pointer;
    transition: all 0.25s ease;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2310b981' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M19 9l-7 7-7-7'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.8rem center;
}
.select-control:hover { border-color: var(--accent); }
.select-control:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 4px var(--pastel-light);
}

/* ---------- results ---------- */
.results { width: 100%; }
.results-title {
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--text-strong);
    margin: 0 0 0.4rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.6rem;
    flex-wrap: wrap;
}
.platform-chip {
    background: var(--accent-grad);
    color: #fff;
    font-size: 1.1rem;
    font-weight: 700;
    padding: 0.2rem 1rem;
    border-radius: 9999px;
    box-shadow: 0 6px 16px var(--glass-blob);
}
.divider {
    width: 3rem;
    height: 4px;
    border-radius: 9999px;
    background: var(--accent-grad);
    margin: 1rem auto 0;
    opacity: 0.5;
}

.ios-note {
    max-width: 44rem;
    margin: 0 auto 2rem;
    display: flex;
    align-items: flex-start;
    gap: 0.9rem;
    background: var(--pastel-light);
    border: 1px solid var(--card-border);
    border-radius: 18px;
    padding: 1rem 1.25rem;
}
.ios-note-icon {
    flex-shrink: 0;
    background: var(--pastel-mid);
    color: var(--accent);
    padding: 0.5rem;
    border-radius: 9999px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-top: 0.1rem;
}
.ios-note-title {
    font-weight: 700;
    color: var(--text-strong);
    margin: 0 0 0.25rem;
    font-size: 0.95rem;
}
.ios-note-text {
    color: var(--text-body);
    font-size: 0.88rem;
    margin: 0;
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(min(100%, 260px), 1fr));
    gap: 1.25rem;
}
.app-card {
    display: flex;
    flex-direction: column;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-radius: 22px;
    padding: 1.4rem;
    box-shadow: 0 12px 28px -20px rgba(0,0,0,0.16);
    transition: all 0.3s ease;
    overflow: hidden;
    position: relative;
}
.app-card::before {
    content: '';
    position: absolute;
    inset: 0 0 auto 0;
    height: 3px;
    background: var(--accent-grad);
    opacity: 0;
    transition: opacity 0.3s ease;
}
.app-card:hover {
    transform: translateY(-6px);
    box-shadow: 0 22px 40px -22px rgba(0,0,0,0.24);
    border-color: var(--pastel-deep);
}
.app-card:hover::before { opacity: 1; }
.app-card-top {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 0.6rem;
    margin-bottom: 0.6rem;
}
.app-name {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--text-strong);
    margin: 0;
    word-break: break-all;
    font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}
.kernel-badge {
    flex-shrink: 0;
    font-size: 0.68rem;
    font-weight: 600;
    color: var(--accent);
    background: var(--pastel-light);
    border: 1px solid var(--pastel-deep);
    padding: 0.15rem 0.5rem;
    border-radius: 9999px;
}
.app-desc {
    font-size: 0.88rem;
    color: var(--text-body);
    margin: 0 0 1.25rem;
    flex: 1;
    min-height: 2.9rem;
}
.app-card-foot { margin-top: auto; }

.download-btn {
    width: 100%;
    border: none;
    padding: 0.7rem 1rem;
    border-radius: 14px;
    font-family: inherit;
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    transition: all 0.25s ease;
}
.download-btn.ready {
    background: var(--pastel-light);
    color: var(--accent);
    border: 1.5px solid var(--pastel-deep);
}
.download-btn.ready:hover {
    background: var(--accent-grad);
    color: #fff;
    border-color: transparent;
    box-shadow: 0 10px 20px -8px var(--glass-blob);
    transform: translateY(-2px);
}
.download-btn.loading {
    background: var(--pastel-mid);
    color: var(--text-strong);
    border: 1.5px solid var(--pastel-deep);
    cursor: wait;
}
.download-btn.disabled {
    background: color-mix(in srgb, var(--card-bg) 60%, transparent);
    color: var(--text-muted);
    border: 1.5px solid var(--card-border);
    cursor: not-allowed;
}
.download-btn:focus-visible {
    outline: none;
    box-shadow: 0 0 0 4px var(--pastel-light);
}

/* ---------- footer ---------- */
.footer {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    width: 100%;
    text-align: center;
    z-index: 1;
    padding-bottom: calc(1rem + env(safe-area-inset-bottom));
}
.footer-text {
    font-size: 0.85rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.35rem;
    flex-wrap: wrap;
}
.brand-link {
    border: none;
    background: transparent;
    color: var(--text-strong);
    font-weight: 700;
    cursor: pointer;
    font-family: inherit;
    font-size: inherit;
    padding: 0;
    transition: color 0.2s ease;
}
.brand-link:hover { color: var(--accent); }
.footer-gemini {
    color: transparent;
    background: var(--accent-grad);
    -webkit-background-clip: text;
    background-clip: text;
    font-weight: 700;
}
.footer-heart { color: var(--accent-soft); }
.footer-copy { opacity: 0.7; }

/* ---------- responsive: very small phones (< 420px) ---------- */
@media (max-width: 419px) {
    .main { padding: 1.25rem 0.75rem 7rem; gap: 1.75rem; }
    .toolbar-inner { padding: 0.75rem 0.9rem; }
    .brand-pill { font-size: 0.82rem; padding: 0.3rem 0.65rem; }
    .brand-text { display: none; }
    .theme-toggle { padding: 0.4rem 0.7rem; }
    .theme-toggle-text { display: none; }
    .unlock-wrap { padding: 2rem 1.25rem; }
    .hero-title { font-size: 1.7rem; }
    .unlock-code { font-size: 0.78rem; padding: 0.5rem 0.9rem; }
    .intro-card { padding: 1.75rem 1.25rem; }
    .intro-title { font-size: 1.5rem; }
    .card-grid { gap: 1rem; }
    .app-card { padding: 1.15rem; }
    .results-title { font-size: 1.2rem; }
    .ios-note { padding: 0.9rem 1rem; }
    .platform-chip { font-size: 0.95rem; padding: 0.15rem 0.75rem; }
}

/* ---------- responsive: phones (420px - 640px) ---------- */
@media (min-width: 420px) and (max-width: 640px) {
    .main { padding: 2rem 1rem 7rem; }
    .toolbar-inner { flex-direction: column; align-items: flex-start; gap: 0.6rem; }
    .toolbar-actions { width: 100%; justify-content: space-between; flex-wrap: wrap; }
    .steps { flex-direction: column; align-items: stretch; }
    .step { width: 100%; }
    .select-control { width: 100%; min-width: 0; }
    .results-title { font-size: 1.3rem; }
    .intro-card { padding: 2rem 1.25rem; }
}

/* ---------- responsive: tablets (641px - 768px) ---------- */
@media (min-width: 641px) and (max-width: 768px) {
    .main { padding: 2.25rem 1.25rem 7rem; }
    .toolbar-inner { padding: 0.85rem 1.75rem; }
    .intro-card { padding: 2.25rem 1.75rem; }
    .steps { gap: 0.7rem; }
    .select-control { min-width: 9.5rem; }
}

/* ---------- responsive: standard tablets / portrait (769px - 900px) ---------- */
@media (min-width: 769px) and (max-width: 900px) {
    .toolbar-inner { padding: 0.9rem 1.25rem; }
    .select-control { min-width: 9.75rem; }
}

/* ===== very wide screens (x4K, ultra-wide) ===== */
@media (min-width: 1600px) {
    .main {
        max-width: 78rem;
        padding-top: 4rem;
    }
    .card-grid {
        grid-template-columns: repeat(auto-fill, minmax(min(100%, 320px), 1fr));
    }
}

/* ===== desktops in portrait / narrow laptop windows (900px - 1024px) ===== */
@media (min-width: 901px) and (max-width: 1024px) {
    .card-grid {
        grid-template-columns: repeat(auto-fill, minmax(min(100%, 280px), 1fr));
    }
}

/* ===== landscape phones & small landscape tablets (max-height viewport) ===== */
@media (min-width: 641px) and (max-width: 1024px) and (max-height: 600px) {
    .main { padding-top: 1.5rem; }
    .toolbar-inner { padding: 0.55rem 1.25rem; }
    .blob-3 { display: none; }
}

/* ===== reduce motion ===== */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.001ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.001ms !important;
    }
}