/* Modern CSS layer organization for better cascade control */
@layer reset, base, layout, components;

@layer reset {
    *,
    *::before,
    *::after {
        box-sizing: border-box;
        margin: 0;
        padding: 0;
    }
    button {
        background: none;
        border: none;
        cursor: pointer;
    }
    input,
    select,
    option {
        border: none;
        background: none;
        font: inherit;
    }
    dialog {
        margin: auto;
        background: none;
        border: none;
    }
}

@layer base {
    :root {
        /* Theme */
        accent-color: var(--accent-color);
        color-scheme: light dark;
        &[data-theme="dark"] {
            color-scheme: dark;
        }
        &[data-theme="light"] {
            color-scheme: light;
        }

        /* Primitives */
        --coral: hsl(16, 100%, 60%);
        --jet-black: hsl(200, 0%, 15%);
        --eggshell: hsl(46, 46%, 89%);

        /* Dynamic surface colors using modern CSS 'from' syntax */
        --light-surface-color: hsl(from var(--background-color) h s 80% / 0.9);
        --dark-surface-color: hsl(from var(--background-color) h s 20% / 0.9);

        --padding: 0.5rem;
        --border-radius: 0.25rem;
        --transition-speed: 0.5s ease;

        /* Color Variables */
        --accent-color: var(--coral);
        /* Modern light-dark() function for automatic theme colors */
        --text-color: light-dark(black, white);
        --background-color: light-dark(var(--eggshell), var(--jet-black));
        --surface-color: light-dark(
            var(--light-surface-color),
            var(--dark-surface-color)
        );
    }

    body {
        position: relative;
        font-family: "Nunito Sans", sans-serif;
        line-height: 1.6;
        text-wrap: balance;
        min-height: 100vh;
        display: flex;
        flex-direction: column;
        color: var(--text-color);
        background-color: var(--background-color);
        scroll-behavior: smooth;
        transition: background-color 0.5s ease, color 0.5s ease;
        animation: fadeIn 0.8s ease-out;
    }

    @keyframes fadeIn {
        from {
            opacity: 0;
            transform: translateY(20px);
        }
        to {
            opacity: 1;
            transform: translateY(0);
        }
    }
    button {
        color: var(--text-color);
        padding: var(--padding) calc(var(--padding) * 2);
        border: solid var(--accent-color);
        border-radius: var(--border-radius);
    }
    option,
    optgroup,
    select {
        background: var(--background-color);
        color: var(--text-color);
    }
    option {
        font-weight: normal;
    }
}

@layer layout {
    header {
        display: flex;
        align-items: center;
        justify-content: space-between;
        padding: var(--padding);
        width: 50vw;
        margin: 1rem auto;
        border-radius: calc(var(--border-radius) * 2);
        background-color: var(--surface-color);
        position: sticky;
        top: 1rem;
        z-index: 1000;
        @media (width < 600px) {
            width: 90vw;
        }
    }
    main {
        display: flex;
        flex-direction: column;
        align-items: center;
        gap: 2rem;
        flex: 1;
        & #hero-banner {
            text-align: center;
            padding: var(--padding);
            & h1 {
                font-size: 3rem;
                font-weight: bold;
                letter-spacing: 0.05em;
                /* Gradient text effect using modern background-clip */
                background: linear-gradient(
                    to right,
                    var(--text-color),
                    var(--accent-color),
                    var(--text-color)
                );
                background-clip: text;
                -webkit-background-clip: text;
                color: transparent;
                @media (width < 600px) {
                    font-size: 2rem;
                }
            }
            & p {
                font-size: 1.2rem;
                opacity: 0.8;
            }
        }
        & #add-student {
            font-size: 1.2rem;
            font-weight: bold;
            letter-spacing: 0.1em;
            text-transform: uppercase;
            background-color: var(--accent-color);
            transition: background-color var(--transition-speed);
            &:hover {
                background-color: transparent;
            }
            & svg {
                margin-inline-end: 0.5rem;
                vertical-align: middle;
            }
        }
        & #cards-container {
            /* Responsive grid with auto-fitting columns */
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
            gap: 2rem;
            width: 80vw;
            margin: 0 auto;
            @media (max-width: 600px) {
                width: 90vw;
            }
            /* Empty state styling using CSS pseudo-content */
            &:empty {
                display: flex;
                align-items: center;
                justify-content: center;
                color: var(--text-color);
                background-color: var(--surface-color);
                border-radius: calc(var(--border-radius) * 2);
                min-height: 250px;
                &::before {
                    content: "No students registered yet. Click 'ADD STUDENT' to get started!";
                    text-align: center;
                }
            }
        }
    }
}

@layer components {
    /* Theme Toggle */
    html {
        #theme-toggle {
            padding: 0;
            display: flex;
            border: solid var(--accent-color);
            border-radius: var(--border-radius);
            position: relative;
            overflow: hidden;
            /* Sliding background effect using pseudo-element */
            &::before {
                position: absolute;
                content: "";
                width: 100%;
                height: 100%;
                left: 0;
                background-color: var(--accent-color);
                z-index: -1;
                transition: transform 0.5s ease;
            }
            & .icon {
                padding: var(--padding);
                font-size: 1rem;
                background: transparent;
                transition: color 0.2s ease;
            }
        }
        /* Theme-specific positioning for sliding effect */
        &[data-theme="light"] #theme-toggle {
            &::before {
                transform: translateX(-50%);
            }
        }
        &[data-theme="dark"] #theme-toggle {
            &::before {
                transform: translateX(50%);
            }
        }
    }

    /* Dialog and Form */
    dialog {
        transition: opacity var(--transition-speed),
            transform var(--transition-speed);
        /* Modern CSS starting-style for entry animations */
        @starting-style {
            opacity: 0;
            transform: scale(0.8);
        }
        &::backdrop {
            backdrop-filter: blur(5px) brightness(0.5);
            transition: backdrop-filter var(--transition-speed);
            /* Entry animation for backdrop */
            @starting-style {
                backdrop-filter: blur(0px) brightness(1);
            }
        }
        &:modal {
            border-radius: calc(var(--border-radius) * 2);
            background-color: var(--surface-color);
            padding: calc(var(--padding) * 4);
            width: 50%;
            @media (max-width: 800px) {
                padding: calc(var(--padding) * 3);
                width: 70%;
            }
            @media (max-width: 500px) {
                padding: calc(var(--padding) * 2);
                width: 95%;
            }
        }
        & > div {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-block-end: 1rem;
            & button {
                padding: var(--padding);
            }
        }
        & form {
            display: flex;
            flex-direction: column;
            gap: 1rem;
            align-items: center;
            & div {
                display: flex;
                flex-direction: column;
                gap: 0.5rem;
                width: 100%;
                &:last-child {
                    flex-direction: row;
                    gap: 3rem;
                    justify-content: center;
                }
                & input {
                    border: solid var(--accent-color);
                    padding: var(--padding);
                    border-radius: var(--border-radius);
                }
                & button[type="submit"] {
                    background-color: var(--accent-color);
                    color: var(--text-color);
                    font-weight: bold;
                    letter-spacing: 0.1em;
                    text-transform: uppercase;
                    transition: background-color var(--transition-speed);
                    &:hover {
                        background-color: transparent;
                    }
                }
            }
        }
        & button:not([type="submit"]):hover {
            border-color: var(--text-color);
        }
    }

    /* Avatar */
    .avatar {
        width: 100px;
        height: 100px;
        border-radius: 50%;
        margin: 0 auto;
        background-color: var(--background-color);
        box-shadow: inset 2px 2px 2px var(--accent-color),
            0 0 5px var(--accent-color);
        border: 1px solid var(--accent-color);
        color: var(--text-color);
        display: flex;
        align-items: center;
        justify-content: center;
        font-weight: bold;
        font-size: 2.5rem;
        font-style: italic;
        text-shadow: 2px 2px 2px var(--accent-color);
        letter-spacing: 0.1em;
    }

    /* Card */
    .card {
        background-color: var(--surface-color);
        border-radius: calc(var(--border-radius) * 2);
        padding: calc(var(--padding) * 2);
        display: grid;
        gap: 1rem 2rem;
        grid-template-columns: 1fr 2fr;
        align-items: center;
        @media (width < 500px) {
            gap: 1rem;
        }
        /* Dynamic shadow using modern 'from' syntax for color manipulation */
        box-shadow: 2px 2px 5px hsl(from var(--accent-color) h s l / 0.5);
        transition: opacity var(--transition-speed),
            transform var(--transition-speed);
        transition-delay: 0.1s;
        /* Entry animation for dynamically added cards */
        @starting-style {
            opacity: 0;
            transform: scale(0.8);
        }
        & .card-header {
            grid-column: span 2;
            display: flex;
            justify-content: space-between;
            align-items: center;
            & h3 {
                color: var(--accent-color);
                font-size: 1.5rem;

                text-transform: capitalize;
            }
            & .actions button {
                background-color: var(--background-color);
                border: none;
                padding: var(--padding);
                &:hover {
                    box-shadow: 0 0 5px var(--accent-color);
                }
            }
        }
        & .info {
            display: flex;
            flex-direction: column;
            gap: 0.5rem;
            & p {
                word-break: break-word;
                letter-spacing: 0.1em;
                & svg {
                    color: var(--accent-color);
                }
            }
        }
    }
}