:root {
    --bg-top: #0b1020;
    --bg-bottom: #1e3a5f;
    --panel: rgba(8, 15, 30, 0.82);
    --panel-border: rgba(148, 163, 184, 0.22);
    --text: #e5eef9;
    --muted: #a7b9d3;
    --accent: #5eead4;
    --accent-deep: #14b8a6;
    --board-frame: #1d4ed8;
    --board-shadow: #0f172a;
    --board-hole: #0b1730;
    --red: #f43f5e;
    --red-deep: #be123c;
    --yellow: #facc15;
    --yellow-deep: #ca8a04;
    --white: #f8fafc;
}

* {
    box-sizing: border-box;
}

html, body {
    margin: 0;
    min-height: 100%;
}

body {
    font-family: "Trebuchet MS", "Segoe UI", sans-serif;
    color: var(--text);
    background:
        radial-gradient(circle at top, rgba(94, 234, 212, 0.22), transparent 30%),
        linear-gradient(160deg, var(--bg-top), var(--bg-bottom));
    padding: 24px;
}

body::before,
body::after {
    content: "";
    position: fixed;
    inset: auto;
    width: 320px;
    height: 320px;
    border-radius: 50%;
    filter: blur(90px);
    opacity: 0.28;
    pointer-events: none;
}

body::before {
    top: -80px;
    right: -40px;
    background: var(--accent);
}

body::after {
    bottom: -120px;
    left: -70px;
    background: var(--red);
}

.back-link {
    position: fixed;
    top: 20px;
    left: 20px;
    z-index: 2;
    color: var(--text);
    text-decoration: none;
    background: rgba(8, 15, 30, 0.7);
    border: 1px solid var(--panel-border);
    border-radius: 999px;
    padding: 10px 16px;
    backdrop-filter: blur(10px);
}

.app-shell {
    width: min(1180px, 100%);
    margin: 64px auto 0;
    display: grid;
    gap: 24px;
    grid-template-columns: 360px minmax(0, 1fr);
}

.hero-panel,
.board-panel,
.error-shell {
    background: var(--panel);
    border: 1px solid var(--panel-border);
    box-shadow: 0 30px 80px rgba(0, 0, 0, 0.35);
    backdrop-filter: blur(18px);
}

.hero-panel,
.board-panel {
    border-radius: 28px;
    padding: 28px;
}

.board-panel {
    display: flex;
    flex-direction: column;
}

.eyebrow {
    margin: 0 0 12px;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 0.18em;
    font-size: 0.8rem;
}

h1 {
    margin: 0;
    font-size: clamp(2.5rem, 5vw, 4rem);
    line-height: 0.95;
}

.subtitle {
    color: var(--muted);
    font-size: 1.05rem;
    line-height: 1.6;
    margin: 16px 0 24px;
}

.control-grid {
    display: grid;
    gap: 14px;
}

.field {
    display: grid;
    gap: 8px;
    font-weight: 700;
}

.field span {
    color: var(--muted);
    font-size: 0.95rem;
}

select,
.join-row input,
.btn {
    border-radius: 16px;
    border: 1px solid transparent;
    font: inherit;
}

select,
.join-row input {
    background: rgba(15, 23, 42, 0.9);
    color: var(--text);
    padding: 14px 16px;
    border-color: rgba(148, 163, 184, 0.18);
}

.join-row input {
    min-width: 0;
}

.button-row {
    display: flex;
    gap: 12px;
    margin: 22px 0;
    flex-wrap: wrap;
}

.hidden {
    display: none !important;
}

.btn {
    cursor: pointer;
    padding: 14px 18px;
    font-weight: 700;
    transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

.btn:hover {
    transform: translateY(-1px);
}

.btn-primary {
    color: #06221d;
    background: linear-gradient(135deg, var(--accent), #99f6e4);
    box-shadow: 0 14px 28px rgba(20, 184, 166, 0.22);
}

.btn-secondary {
    color: var(--text);
    background: rgba(15, 23, 42, 0.95);
    border-color: rgba(148, 163, 184, 0.22);
}

.status-card {
    background: rgba(15, 23, 42, 0.75);
    border: 1px solid rgba(148, 163, 184, 0.16);
    border-radius: 20px;
    padding: 18px;
}

.remote-card {
    margin-top: 18px;
    padding: 18px;
    background: rgba(15, 23, 42, 0.75);
    border: 1px solid rgba(148, 163, 184, 0.16);
    border-radius: 20px;
}

.remote-title,
.invite-label {
    margin: 0 0 10px;
    color: var(--muted);
    text-transform: uppercase;
    letter-spacing: 0.12em;
    font-size: 0.78rem;
}

.remote-actions {
    margin: 0 0 18px;
}

.join-row {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 10px;
    align-items: stretch;
}

.invite-shell {
    margin-top: 18px;
    padding: 16px;
    border-radius: 18px;
    background: rgba(8, 15, 30, 0.72);
    border: 1px solid rgba(148, 163, 184, 0.16);
}

.room-code-display {
    margin: 0 0 14px;
    font-size: 1.75rem;
    font-weight: 800;
    letter-spacing: 0.18em;
    color: var(--accent);
}

#status-text {
    margin: 0 0 8px;
    font-size: 1.05rem;
    font-weight: 700;
}

#hint-text {
    margin: 0;
    color: var(--muted);
}

.board-header {
    display: flex;
    justify-content: space-between;
    gap: 16px;
    align-items: baseline;
    margin-bottom: 20px;
}

.board-label {
    margin: 0;
    color: var(--muted);
    text-transform: uppercase;
    letter-spacing: 0.16em;
    font-size: 0.8rem;
}

.turn-indicator {
    margin: 0;
    font-size: 1rem;
    font-weight: 700;
}

.turn-indicator.red {
    color: var(--red);
}

.turn-indicator.yellow {
    color: var(--yellow);
}

.column-controls {
    display: grid;
    grid-template-columns: repeat(7, minmax(0, 1fr));
    gap: 10px;
    margin-bottom: 14px;
    width: min(100%, 72vh);
    margin-inline: auto;
}

.column-btn {
    background: rgba(14, 25, 47, 0.95);
    border: 1px solid rgba(148, 163, 184, 0.18);
    color: var(--text);
    border-radius: 16px;
    padding: 12px 0;
    font-weight: 800;
    cursor: pointer;
}

.column-btn:hover:not(:disabled),
.column-btn:focus-visible:not(:disabled) {
    outline: none;
    background: rgba(37, 99, 235, 0.95);
}

.column-btn:disabled {
    opacity: 0.38;
    cursor: not-allowed;
}

.board {
    display: grid;
    grid-template-columns: repeat(7, minmax(0, 1fr));
    gap: 10px;
    padding: 16px;
    width: min(100%, 72vh);
    margin-inline: auto;
    border-radius: 28px;
    background:
        linear-gradient(180deg, #3b82f6, var(--board-frame));
    box-shadow:
        inset 0 -10px 0 rgba(15, 23, 42, 0.18),
        0 25px 50px rgba(15, 23, 42, 0.45);
}

.cell {
    position: relative;
    width: 100%;
    aspect-ratio: 1;
    border-radius: 50%;
    background:
        radial-gradient(circle at 35% 30%, #1e293b, var(--board-hole) 70%);
    box-shadow: inset 0 7px 12px rgba(0, 0, 0, 0.45);
    overflow: hidden;
}

.disc {
    position: absolute;
    inset: 7%;
    border-radius: 50%;
    transform: translateY(-125%);
    transition: transform 0.28s ease-out, box-shadow 0.28s ease-out;
    box-shadow:
        inset -10px -10px 20px rgba(0, 0, 0, 0.22),
        inset 10px 10px 18px rgba(255, 255, 255, 0.18);
}

.disc.red {
    background: radial-gradient(circle at 30% 30%, #fb7185, var(--red-deep));
}

.disc.yellow {
    background: radial-gradient(circle at 30% 30%, #fde047, var(--yellow-deep));
}

.cell.filled .disc {
    transform: translateY(0);
}

.cell.winning .disc {
    box-shadow:
        0 0 0 3px rgba(255, 255, 255, 0.35),
        0 0 26px rgba(255, 255, 255, 0.75),
        inset -10px -10px 20px rgba(0, 0, 0, 0.22),
        inset 10px 10px 18px rgba(255, 255, 255, 0.22);
}

.legend {
    display: flex;
    gap: 18px;
    flex-wrap: wrap;
    align-items: center;
    margin-top: 18px;
    justify-content: center;
    color: var(--muted);
}

.legend span {
    display: inline-flex;
    align-items: center;
    gap: 10px;
}

.disc.preview,
.win-marker {
    position: relative;
    inset: auto;
    width: 22px;
    height: 22px;
    transform: none;
    flex: 0 0 auto;
}

.win-marker {
    border-radius: 50%;
    background: rgba(248, 250, 252, 0.75);
    box-shadow: 0 0 18px rgba(248, 250, 252, 0.7);
}

.error-page {
    display: grid;
    place-items: center;
}

.error-shell {
    width: min(520px, 100%);
    border-radius: 28px;
    padding: 40px 32px;
    text-align: center;
}

@media (max-width: 980px) {
    .app-shell {
        grid-template-columns: 1fr;
        margin-top: 72px;
    }

    .column-controls,
    .board {
        width: 100%;
    }

    .legend {
        justify-content: flex-start;
    }
}

@media (max-width: 640px) {
    body {
        padding: 16px;
    }

    .hero-panel,
    .board-panel {
        padding: 20px;
    }

    .column-controls,
    .board {
        gap: 8px;
    }

    .join-row {
        grid-template-columns: 1fr;
    }

    .column-btn {
        font-size: 0.9rem;
        padding: 10px 0;
    }
}