:root {
    --primary: #2563eb;
    --bg: #f5f7fb;
    --card: #ffffff;
    --text: #1e293b;
    --muted: #64748b;
    --border: #e2e8f0;
}
* { box-sizing: border-box; }
body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background: var(--bg);
    color: var(--text);
}
.container {
    max-width: 640px;
    margin: 40px auto;
    padding: 0 16px;
}
h1 { text-align: center; margin-bottom: 24px; }
.mailbox-box {
    display: flex;
    gap: 8px;
    background: var(--card);
    padding: 12px;
    border-radius: 12px;
    border: 1px solid var(--border);
}
.mailbox-box input {
    flex: 1;
    padding: 10px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 15px;
    background: var(--bg);
}
.mailbox-box button {
    padding: 10px 14px;
    border: none;
    border-radius: 8px;
    background: var(--primary);
    color: #fff;
    cursor: pointer;
    font-size: 14px;
}
.mailbox-box button:hover { opacity: 0.9; }
.expiry { text-align: center; color: var(--muted); font-size: 13px; margin: 8px 0 24px; }
.inbox { background: var(--card); border-radius: 12px; border: 1px solid var(--border); padding: 16px; }
.inbox h2 { margin-top: 0; font-size: 18px; }
.empty { color: var(--muted); text-align: center; padding: 24px 0; }
.msg-item {
    padding: 12px;
    border-bottom: 1px solid var(--border);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    gap: 12px;
}
.msg-item:last-child { border-bottom: none; }
.msg-item:hover { background: var(--bg); }
.msg-item.unread { font-weight: 600; }
.msg-from { font-size: 14px; }
.msg-subject { font-size: 13px; color: var(--muted); }
.msg-time { font-size: 12px; color: var(--muted); white-space: nowrap; }
.modal {
    position: fixed; inset: 0; background: rgba(0,0,0,0.4);
    display: flex; align-items: center; justify-content: center; padding: 16px;
}
.modal.hidden { display: none; }
.modal-content {
    background: #fff; border-radius: 12px; max-width: 600px; width: 100%;
    max-height: 80vh; overflow-y: auto; padding: 24px; position: relative;
}
#closeModal {
    position: absolute; top: 12px; right: 16px; border: none; background: none;
    font-size: 22px; cursor: pointer; color: var(--muted);
}