* {
    box-sizing: border-box;
}

/* ===== THEME ===== */
:root {
    --bg: linear-gradient(135deg, #f5f7fa, #e4ecf7);
    --card: rgba(255, 255, 255, 0.7);
    --text: #1d1d1f;
    --muted: #6e6e73;
    --border: rgba(255,255,255,0.3);
    --primary: #0071e3;
}

/* DARK */
body.dark {
    --bg: linear-gradient(135deg, #0f0f10, #1a1a1c);
    --card: rgba(30, 30, 32, 0.6);
    --text: #f5f5f7;
    --muted: #aaa;
    --border: rgba(255,255,255,0.08);
    --primary: #0a84ff;
}

/* ===== BASE ===== */
body {
    margin: 0;
    font-family: 'Inter', sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    transition: 0.4s;
}

/* ===== LAYOUT ===== */
.app {
    max-width: 520px;
    margin: auto;
    padding: 20px;
}

/* ===== NAV ===== */
.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.nav h1 {
    font-weight: 600;
    letter-spacing: -0.5px;
}

/* ===== CARD (GLASS EFFECT) ===== */
.card, .cart-card {
    backdrop-filter: blur(18px);
    -webkit-backdrop-filter: blur(18px);

    background: var(--card);
    border-radius: 25px;
    padding: 20px;
    margin-bottom: 15px;

    border: 1px solid var(--border);

    box-shadow:
        0 8px 30px rgba(0,0,0,0.08),
        inset 0 1px rgba(255,255,255,0.4);
}

/* ===== IMAGE ===== */
.product-img {
    width: 100%;
    border-radius: 18px;
    margin-bottom: 15px;
    transition: 0.4s;
}

.product-img:hover {
    transform: scale(1.03);
}

/* ===== TEXT ===== */
.list {
    color: var(--muted);
    font-size: 14px;
}

/* ===== ROW ===== */
.row {
    display: flex;
    gap: 10px;
}

/* ===== INPUT ===== */
input, select {
    width: 100%;
    padding: 13px;
    margin-top: 8px;

    border-radius: 14px;
    border: 1px solid var(--border);

    background: rgba(255,255,255,0.4);
    color: var(--text);

    font-size: 14px;
    transition: 0.2s;
}

body.dark input,
body.dark select {
    background: rgba(255,255,255,0.05);
}

input:focus, select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 2px rgba(0,113,227,0.2);
}

/* ===== BUTTON ===== */
.primary, .checkout {
    width: 100%;
    padding: 14px;
    margin-top: 15px;

    border: none;
    border-radius: 14px;

    background: linear-gradient(135deg, #0071e3, #42a1ff);
    color: white;

    font-size: 15px;
    cursor: pointer;

    transition: 0.25s;
}

.primary:hover, .checkout:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(0,113,227,0.3);
}

/* ===== SUMMARY ===== */
.summary {
    margin-top: 10px;
}

.total {
    font-weight: 600;
    font-size: 16px;
}

/* ===== FOOTER ===== */
.footer {
    text-align: center;
    font-size: 13px;
    color: var(--muted);
}

.footer a {
    color: var(--primary);
    text-decoration: none;
}

/* ===== THEME BUTTON ===== */
.theme-toggle {
    border: none;
    padding: 8px 12px;
    border-radius: 10px;
    background: var(--card);
    cursor: pointer;
}